Author: toxlaw

Improvement in ADHD symptom scores and remaining in treatment are different outcomes. A 2018 Cochrane review found short-term symptom benefits from amphetamines in adults with ADHD, but no clear improvement in overall treatment retention and more withdrawals attributed to adverse events. Those findings can coexist without contradiction.

The review also rated the evidence as low or very low quality. That qualification belongs beside the effect estimates, rather than disappearing when a result crosses a statistical significance threshold.

What evidence was available to this review?

Castells, Blanco-Silvente and Cunill searched the literature in August 2017 and included 19 studies enrolling 2,521 adults. All studies compared an amphetamine with placebo; three also included an active comparator. Mean study duration was 5.3 weeks, with studies ranging from one to 20 weeks.

The drugs were dexamphetamine, lisdexamfetamine and mixed amphetamine salts. Lisdexamfetamine is a dexamphetamine prodrug. The review did not study methamphetamine administration. Its therapeutic adult-ADHD findings cannot be generalized to illicit methamphetamine, repeated high-dose exposure or people without ADHD.

The reported study dose ranges were 10.2–21.8 mg/day for dexamphetamine, 30–70 mg/day for lisdexamfetamine and 12.5–80 mg/day for mixed amphetamine salts. These are pharmaceutical dosing descriptions, not measured biological concentrations or dose recommendations.

Why is 2,521 not the denominator for every result?

Trials did not all report the same endpoints or contribute usable data to every analysis. Each pooled comparison therefore has its own study and participant count.

Selected amphetamine-versus-placebo findings from the historical review; confidence intervals are 95%.

Outcome	Included evidence	Pooled estimate
Clinician-rated ADHD symptom severity	13 studies; 2,028 participants	Standardized mean difference −0.90; CI −1.04 to −0.75
Patient-rated ADHD symptom severity	6 studies; 120 participants	Standardized mean difference −0.51; CI −0.75 to −0.28
Retention in treatment	17 studies; 2,323 participants	Risk ratio 1.06; CI 0.99 to 1.13
Withdrawal because of adverse events	17 studies; 2,409 participants	Risk ratio 2.69; CI 1.63 to 4.45

The same number of studies in the final two rows does not mean identical participants or identical denominators. Reusing the review’s total enrollment for every outcome would misdescribe the analyses.

What does symptom improvement mean here?

Negative standardized mean differences favored amphetamines on the symptom-rating scales. A standardized effect expresses the difference in standard-deviation units so that results from different scales can be combined. It is not a 90% symptom reduction, a count of symptoms eliminated or a probability that one individual will respond.

Clinician and patient ratings also came from different evidence sets. The difference between their pooled estimates is not a within-person test proving that clinicians saw more improvement than patients. Neither rating directly measures driving, work productivity or every aspect of daily functioning.

Why was retention not clearly improved?

The pooled retention ratio was 1.06, but its confidence interval included one, the no-difference value. The review therefore did not establish improved retention with amphetamines. This is different from demonstrating exact equivalence or proving that no participant benefited.

Retention integrates many reasons for continuing or discontinuing. A symptom improvement can coexist with side effects, inconvenience or other reasons for leaving a trial. It should not be assumed that better symptom scores necessarily lead to more people completing treatment.

How should the adverse-event withdrawal ratio be read?

A risk ratio of 2.69 describes a relative comparison with placebo for withdrawals attributed to adverse events. It is not a 269% absolute withdrawal probability. The corresponding absolute difference depends on the baseline withdrawal risk in the comparison population.

This endpoint is narrower than experiencing any adverse event. It counts leaving because of an adverse event, not every reported symptom, every serious event or all causes of discontinuation. It also does not mean that the overall chance of staying in treatment must change by the inverse of 2.69: all-cause retention and adverse-event withdrawal are different outcomes.

Why did evidence quality remain limited?

No included study had low risk of bias across every domain assessed. The review identified concerns about blinding because stimulants can produce noticeable subjective effects, attrition, and possible carry-over in crossover studies. Sixteen studies were industry funded, one publicly funded and two did not report funding sources.

Funding alone does not demonstrate that a result is false. The review’s judgments concern confidence in the evidence, incorporating design limitations, precision and other factors. A precise-looking effect estimate should not erase those assessments.

The selected participants and short follow-up also limit generalization. A mean duration of 5.3 weeks cannot establish that benefits and harms remain unchanged for years. Conversely, the absence of long-term evidence in this historical review is not a claim that no later research exists.

What is the appropriate practical conclusion?

This review supported short-term symptom improvement in its adult ADHD populations, alongside uncertain retention benefit and increased adverse-event withdrawals. It did not establish an individual treatment outcome, a diagnostic response test or a drug-concentration impairment rule.

For a scientific or forensic explanation, preserve the specific outcome, denominator and uncertainty. A measured amphetamine result cannot establish that someone experienced the average therapeutic benefit, suffered an adverse event or was functionally impaired at a particular time.

Scientific source

Castells X, Blanco-Silvente L, Cunill R. Amphetamines for attention deficit hyperactivity disorder (ADHD) in adults. Cochrane Database of Systematic Reviews. 2018;(8):CD007813. doi:10.1002/14651858.CD007813.pub3. Full-text systematic review. Historical evidence synthesis; literature search August 2017.

A lower postmortem quetiapine concentration does not identify a single degradation mechanism or exclude an earlier toxic exposure. A hospital-to-mortuary study found lower later concentrations in most of 30 paired cases, but specimen type, time before death and incomplete treatment records complicated the comparison.

Thirty quetiapine pairs within a larger compilation

Mantinieks and colleagues reviewed 811 hospital-death coronial cases from Victoria, Australia, during 2009–2017. Their compilation reported 42 drugs and metabolites with at least ten paired earlier and postmortem results each. Quetiapine contributed 30 pairs.

The earlier clinical specimen could be whole blood, serum or plasma. The institute generally analyzed the sample collected closest to hospital admission. It was not necessarily a sample taken just before death.

Postmortem blood was approximately 2–5 mL collected by leg puncture from the femoral region after mortuary admission. Samples contained 1% w/v sodium fluoride and potassium oxalate, were refrigerated at 4°C and were typically analyzed within 24 hours. Earlier specimens were typically frozen at −20°C after receipt.

What did the paired concentrations show?

The median earlier quetiapine concentration was 0.19 mg/L, range 0.027–0.75 mg/L. The postmortem median was 0.080 mg/L, range 0.011–1.7 mg/L. The median of individual postmortem/antemortem ratios was 0.55, range 0.03–2.5. The paired difference was statistically significant, p = 0.02.

The authors described a net reduction in 22 of the 30 cases. This was a directional observation between the collected specimens. The individual range also included later concentrations above earlier values, so the group result did not establish that quetiapine always falls.

The median interval from earlier collection to death was 20 hours, while the median death-to-postmortem collection interval was 19 hours. Changes during those two periods could not be separated by comparing only the endpoints.

Why “breakdown” did not identify when or how the change occurred

The paper discussed drug instability and used the term net breakdown. The retrospective design did not experimentally apportion each decrease among antemortem elimination, matrix differences, postmortem redistribution and degradation.

About 35% of the earlier specimens overall were plasma or serum. Quetiapine partitions differently between those matrices and whole blood. Restricting the quetiapine comparison to earlier whole blood raised the median ratio to 0.76. That subset analysis highlighted a matrix influence without supplying a universal conversion.

Last-dose timing and individual pharmacokinetics were unknown. Incomplete clinical records also prevented reliable identification of drugs given after the earlier specimen. The first sample therefore could not automatically be treated as the person’s concentration at death.

What did the cause-of-death observations add?

Five quetiapine cases were attributed to mixed-drug toxicity. Only one, identified in the paper as case 26, specifically attributed quetiapine as a main contributor. These were case interpretations within an observational series, not a concentration-threshold experiment.

A lower later value cannot by itself establish that quetiapine was irrelevant earlier. Conversely, an earlier positive finding does not independently prove quetiapine caused death. The complete treatment history, pathology and other substances remain relevant.

The analytical and sampling boundaries

Routine toxicology included validated LC–MS/MS procedures. The article referred to earlier analytical methods rather than supplying a complete quetiapine validation table. It did not establish a new impairment cutoff or a dose-to-concentration model.

Femoral collection used blind puncture, which the authors recognized could introduce blood or fluid from elsewhere. The bodies were not obviously traumatized, burned or decomposed. These selection and collection conditions should not be generalized silently to advanced decomposition or extensive injury.

What should be retained in an individual review?

Preserve the actual earlier matrix, collection times, femoral collection method, both concentrations and their units. Dividing a postmortem concentration by 0.55 or 0.76 would not recover a validated individual predeath value. The observed paired decrease and its possible causes should remain separate statements.

A different reporting issue arises when quetiapine is identified below the quantitation limit; detection there must remain distinct from an exact concentration.

Primary source

Mantinieks D, Gerostamoulos D, Glowacki L, et al. Postmortem Drug Redistribution: A Compilation of Postmortem/Antemortem Drug Concentration Ratios. Journal of Analytical Toxicology. 2021;45:368–377. doi:10.1093/jat/bkaa107.

A reported 16-fold median postmortem/antemortem pholcodine ratio was not a universal measure of redistribution. In the same study, restricting the comparison to earlier whole-blood specimens produced a median ratio of 5.0. Specimen type was part of what the ratio compared.

What was the underlying study?

Mantinieks and colleagues compiled 811 hospital-death coronial cases from Victoria, Australia, reported during 2009–2017. They compared earlier clinical specimens with femoral blood taken at mortuary admission, reporting 42 drugs and metabolites with at least ten pairs each. Pholcodine had 16 pairs, not 811.

The clinical specimens could be whole blood, plasma or serum. The institute generally selected samples taken closest to hospital admission, rather than closest to death. These were not necessarily terminal concentrations.

Postmortem femoral blood, approximately 2–5 mL, was obtained by leg puncture as soon as practicable after mortuary admission. It was preserved with 1% w/v sodium fluoride and potassium oxalate, stored at 4°C and typically analyzed within 24 hours. Earlier specimens were typically stored at −20°C after receipt.

What did the 16 pholcodine pairs show?

The median earlier concentration was 0.015 mg/L, range 0.002–0.072 mg/L. The median postmortem concentration was 0.18 mg/L, range 0.001–0.69 mg/L. The median of the individual postmortem/antemortem ratios was 16, with a range of 0.24–47. The paired comparison was statistically significant, p = 0.001.

The median earlier-sample-to-death interval was 20 hours, and the median death-to-postmortem-collection interval was 17 hours. These intervals include an antemortem period in which drug disposition or further administration could have occurred; they are not a controlled postmortem-only time course.

The ratio of the two group medians is also not the median of the individual ratios. Each reported summary must retain its own calculation and denominator.

What changed when both specimens were whole blood?

About 35% of the study’s earlier specimens overall were plasma or serum. Pholcodine can distribute unevenly between blood components, so comparing those matrices with later whole blood can contribute to the numerical difference.

When the authors restricted the pholcodine comparison to the seven cases with earlier whole blood, the median ratio was 5.0, range 0.24–17. This was a smaller subset of different available cases. It was not a paired experiment measuring serum, plasma and whole blood in every one of the original 16 people.

The result shows why matrix identity matters. It does not establish that the change from 16 to 5.0 was entirely caused by matrix partitioning, or validate either number as an adjustment for a new case.

Redistribution was plausible but not isolated

The authors considered pholcodine’s physicochemical properties and tissue accumulation compatible with redistribution. The paired observations did not directly measure release from each person’s tissue reservoirs or separate it from all other processes.

Incomplete medical records prevented reliable identification of medication administered after the earlier specimen. Last-dose timing, incomplete distribution and individual pharmacokinetic differences were also unknown. Blind femoral puncture carried a possible contamination limitation. The included bodies were not obviously traumatized, burned or decomposed, limiting extrapolation to those conditions.

How were concentrations established?

Routine toxicology included validated LC–MS/MS procedures. The article referred to earlier method publications; it did not provide a pholcodine-specific numerical detection limit or complete validation table. It should not be described as demonstrating analytical performance beyond what it actually reported.

A drug measurement is also different from proof that the drug caused death. The concentration pairs did not establish a lethal threshold, impairment boundary or administered dose.

What belongs beside a quoted ratio?

Keep specimen type, anatomical site, both collection times, units and the number of pairs attached to the statistic. No valid individual predeath concentration results from simply dividing postmortem pholcodine by 16 or 5.0.

For related collection-time evidence, see why later postmortem drug results can rise, fall or remain similar.

Primary source

Mantinieks D, Gerostamoulos D, Glowacki L, et al. Postmortem Drug Redistribution: A Compilation of Postmortem/Antemortem Drug Concentration Ratios. Journal of Analytical Toxicology. 2021;45:368–377. doi:10.1093/jat/bkaa107.

A missing MDMA cardiac-to-femoral ratio can reflect an analytical range limit rather than absence of MDMA. A Dutch postmortem study reported nine cases in which cardiac MDMA exceeded the upper quantitation limit and no subsequent diluted quantification was performed, leaving no numerical MDMA ratio.

Why a positive finding may not yield a usable concentration

de Groot and colleagues reviewed Netherlands Forensic Institute casework from January 2010 through July 2020. Inclusion required a studied compound to be quantified in both femoral and central blood. The amphetamine-group dataset included 112 cases, with 75 amphetamine, 39 MDMA and 35 MDA paired ratios. The same case could contribute more than one analyte.

Screening and quantitative measurement were separate parts of the workflow. Detected compounds underwent quantitative UPLC–MS/MS. A positive analytical finding did not guarantee that both specimens had numerical results within the procedure’s supported quantitative range.

The upper boundary mattered in nine cases

The reported seven-point calibration interval for both MDMA and MDA was 0.005–1 mg/L. In nine of the 35 MDA cases, an MDMA C/P ratio was unavailable because cardiac MDMA was above the upper limit and the laboratory did not subsequently quantify a diluted sample.

A result above an upper limit is not the same as a result equal to that limit. Substituting 1 mg/L as though it were the measured concentration would create an artificial ratio. The paper supplied no exact cardiac concentration for those nine above-range findings from which a numerical ratio could be reconstructed.

A properly supported diluted reanalysis can address an above-range sample, but that additional measurement must actually have occurred. It cannot be supplied retrospectively by assuming the response stayed linear beyond the calibration interval.

Two different reasons for unequal MDMA and MDA counts

Among the 39 MDMA cases with ratios, 26 also had an MDA ratio. In the remaining 13, MDA was not detected and MDMA concentrations were described as low. The authors interpreted MDA as an in-vivo metabolite of MDMA in the included material.

The nine additional MDA cases had a different issue: MDA was quantitatively available, while MDMA’s cardiac concentration exceeded the upper range without diluted quantification. These situations should not be merged into one category called negative testing.

Neither absence of a reported MDA signal nor an unavailable MDMA ratio establishes a known time since use. The study did not validate a detection-pattern clock or a dose reconstruction for these cases.

Collection and method details remain part of the result

Femoral blood was obtained by syringe after targeted dissection and before internal examination. Central blood was obtained from the right atrium or inferior vena cava with the heart in place. Sodium-fluoride/sodium-heparin tubes were stored at −20°C; analysis occurred within three months after collection.

For MDMA, Table 2 reported accuracy deviation −5%, precision 6% and recovery 94%. MDA figures were −11%, 5% and 84%, respectively. These are validation results for the reported quantitative method, not proof of accuracy at an unmeasured concentration above its upper range.

Missing high results can limit a ratio dataset

Requiring two quantified concentrations means the available-ratio population depends partly on analytical coverage. The nine cases demonstrate why a ratio table cannot automatically be read as including every positive specimen or every high-concentration case.

The study did not quantify how these omitted MDMA ratios would have altered the summary distribution. It would therefore also be unwarranted to assert the direction or size of a selection effect without the missing measurements.

What to ask of an above-range report

Preserve the original qualifier, matrix, concentration unit, calibration limits and any dilution record. Distinguish “detected,” “quantified,” “above range” and “not detected.” No numerical ratio, impairment conclusion or cause-of-death inference should be manufactured from a missing concentration.

The corresponding lower-boundary issue is illustrated by quetiapine detected below the quantitation limit.

Primary source

de Groot ADE, Borra LCP, van der Hulst R, et al. Postmortem redistribution of amphetamines and benzodiazepines in humans: Important variables that might be influencing the central blood / peripheral blood ratio. Forensic Science International. 2023;353:111876. doi:10.1016/j.forsciint.2023.111876.

A lower postmortem MDA cardiac-to-femoral ratio in resuscitated cases did not prove that resuscitation caused the difference. In a Dutch casework study, attempted resuscitation and cause of death were associated with one another, preventing a clean separation of their possible influences.

The evidence came from retrospective autopsy records

de Groot and colleagues reviewed Netherlands Forensic Institute investigations from January 2010 through July 2020. Their amphetamine-group dataset contained 112 cases with a studied compound quantified in both femoral and central blood. There were 35 MDA pairs, 39 MDMA pairs and 75 amphetamine pairs; these analyte counts were not separate, mutually exclusive populations.

The authors assumed MDA in these 35 cases had formed in vivo as a metabolite after MDMA exposure. That was their interpretation of the case material, rather than an experimentally established administration history for every person.

Femoral blood was drawn after targeted dissection before internal examination. Central blood came from the right atrium or inferior vena cava with the heart in situ. Samples collected in sodium-fluoride/sodium-heparin tubes were stored at −20°C and analyzed within three months.

What did the resuscitation comparison show?

For MDA, 14 cases with attempted resuscitation had a median cardiac/peripheral ratio of 1.6, range 0.93–2.7. Seventeen cases without attempted resuscitation had a median of 2.4, range 1.0–5.3. The comparison yielded p = 0.003, below the study’s multiple-testing threshold of 0.0045 for the amphetamine group.

Those 31 cases were the available resuscitation comparison, not all 35 MDA cases. A lower median ratio describes the sampled groups. It does not reveal whether cardiac concentration fell, femoral concentration rose, both changed, or different predeath distributions were present.

Why did cause of death matter?

MDA ratios also differed by cause-of-death category. Six trauma-death cases had a median ratio of 3.3, compared with 1.6 in 23 intoxication-death cases. The reported post-hoc comparison was p < 0.001. Trauma and cause of death were themselves associated.

The investigators also found an association between cause of death and attempted resuscitation, with χ² = 9.2 and p = 0.026. Resuscitated and nonresuscitated cases therefore differed in relevant circumstances beyond the intervention being examined.

This is why the two findings cannot be joined into the claim that CPR reduces MDA redistribution. The records did not provide a randomized intervention, matched pre-CPR and post-CPR sampling, or an isolated estimate of resuscitation’s causal effect.

The proposed mechanisms remained possibilities

The authors discussed how trauma could rupture tissues, mix fluids or change barriers. Resuscitation could potentially increase or decrease a site ratio depending on drug reservoirs and timing. These were possible explanations; the study did not experimentally demonstrate which mechanism produced an individual MDA result.

The findings were also compound-specific. The study did not find corresponding statistically significant resuscitation differences for amphetamine or MDMA. The MDA observation should not be expanded into a general rule for stimulants or every resuscitated decedent.

Analytical confirmation did not remove the confounding

Routine screening was followed by quantitative UPLC–MS/MS. MDA’s reported calibration interval was 0.005–1 mg/L, with accuracy deviation −11%, precision 5% and recovery 84%. The ratio itself was dimensionless because both blood measurements used the same concentration units.

Reliable identification and quantitation address what was present in the specimens. They do not make the observational groups interchangeable or establish predeath impairment.

What does this mean for a case review?

Keep the resuscitation history alongside injury pattern, collection details, postmortem interval and the two original concentrations. No validated CPR adjustment factor or reverse calculation to a concentration during life resulted from this study. Detection and a site ratio do not independently establish cause of death.

For another distinction in paired-data interpretation, see why ratios of group averages are different from individual paired ratios.

Primary source

de Groot ADE, Borra LCP, van der Hulst R, et al. Postmortem redistribution of amphetamines and benzodiazepines in humans: Important variables that might be influencing the central blood / peripheral blood ratio. Forensic Science International. 2023;353:111876. doi:10.1016/j.forsciint.2023.111876.

A low body mass index did not establish a validated correction for postmortem midazolam concentration. A Dutch retrospective study found different cardiac-to-femoral ratio patterns across BMI groups, but the comparison did not meet the study’s corrected significance threshold, and the low-BMI group contained only three cases.

What did the study measure?

de Groot and colleagues reviewed Netherlands Forensic Institute casework from January 2010 through July 2020. The benzodiazepine dataset included 179 cases with a studied compound quantified in both cardiac and femoral blood. Midazolam itself had 58 paired results; the larger dataset was not 179 independent midazolam pairs.

Femoral blood was collected by syringe after targeted dissection, before internal examination. Central blood was collected from the right atrium or inferior vena cava with the heart in place. Tubes contained sodium fluoride and sodium heparin. Samples were frozen at −20°C and analyzed within three months of collection.

These were two postmortem collection sites, not paired measurements before and after death. The cardiac/peripheral ratio, abbreviated C/P, described their concentration relationship at autopsy.

Midazolam differed from the other benzodiazepines

Across 58 midazolam cases, the median C/P ratio was 2.3, mean 5.4 and range 0.59–91. Diazepam, by comparison, had a median ratio of 1.1 across 73 cases. These descriptive findings caution against treating every benzodiazepine as having an identical site-distribution pattern.

Midazolam’s median femoral concentration was 0.017 mg/L, compared with 0.060 mg/L in cardiac blood. Those two group medians are not an individual’s paired result and should not be used to calculate a personal correction.

What happened in the BMI comparison?

Midazolam C/P ratios by BMI in the study’s Table 7.

BMI	Cases	Median C/P ratio	Range
Below 18.5 kg/m²	3	0.72	0.59–0.79
18.5–25.0 kg/m²	19	2.5	1.1–12
Above 25.0 kg/m²	35	2.2	0.64–91

The overall BMI comparison yielded p = 0.027. The investigators had adjusted for multiple testing and required p < 0.0038 for the midazolam group. The result therefore remained a potential signal rather than a statistically significant finding under their specified analysis.

The authors acknowledged that this conservative correction could overlook real associations. That limitation supports further investigation; it does not turn an exploratory signal into a proven effect or resolve the uncertainty created by three low-BMI observations.

Adipose storage was a proposed explanation

The authors proposed that differences in predeath adipose accumulation and subsequent redistribution might explain the pattern. They did not directly measure each person’s adipose drug reservoir or experimentally assign body composition. No individual predeath concentration was available to establish how much that person’s blood changed.

Routine screening was followed by quantitative UPLC–MS/MS. For midazolam, the reported calibration limits were 0.001–0.3 mg/L, with accuracy deviation −10%, precision 6% and recovery 81%. Analytical performance supports specimen measurement; it does not validate the proposed biological mechanism.

How should an individual finding be reviewed?

Preserve the collection site, timing, BMI, medication history and both measured concentrations. A C/P ratio below one does not prove absence of postmortem change, and dividing a result by 0.72 or 2.3 would not recover a validated concentration during life. The study established neither a dose formula nor an impairment or cause-of-death threshold.

Exposure provenance is a separate question: midazolam can also reflect emergency treatment before death.

Primary source

de Groot ADE, Borra LCP, van der Hulst R, et al. Postmortem redistribution of amphetamines and benzodiazepines in humans: Important variables that might be influencing the central blood / peripheral blood ratio. Forensic Science International. 2023;353:111876. doi:10.1016/j.forsciint.2023.111876.

A skin-conductance response during methamphetamine cue exposure is not a positive toxicology result. It measures a physiological response associated with sweat-gland activity. It does not chemically identify methamphetamine in the sweat, establish a blood concentration or prove that a person recently took the drug.

A supplied 2025 review by Khan and colleagues discusses this research within a broader account of genes and cognition in methamphetamine use disorder. Its cue-reactivity section provides a useful way to separate physiological arousal, reported craving and analytical drug detection.

What does cue reactivity mean?

Researchers present material associated with drug-taking, such as photographs or videos, and examine changes in subjective experience or physiological measurements. The proposed explanation is learned association: material connected with previous drug experiences can elicit responses even when no drug is administered during the cue presentation.

The review discusses changes such as sweating, heart rate and brain activity as different possible endpoints. It does not establish that every person responds in the same way or that every response has one explanation. Its discussion concerns research in people with methamphetamine use disorder, rather than a validated roadside test of acute intoxication.

What is skin conductance measuring?

Skin conductance response, abbreviated SCR, reflects changes in sweat-gland activity and is used as a physiological indicator of arousal. Calling it an objective measurement identifies how the signal is recorded. It does not make the interpretation uniquely drug-specific.

That distinction is easy to lose when both physiological monitoring and toxicology use the word “sweat.” The chemical question and the arousal question require different measurements.

Three different measurements discussed in interpreting cue research and toxicology.

Measurement	What is observed	What does not follow automatically
Skin conductance during cue presentation	A physiological response associated with sweat-gland activity	Chemical detection of methamphetamine, an administered dose or a blood concentration
Self-reported craving	The participant’s reported desire for the drug under the assessment conditions	Observed consumption, inevitable relapse or contemporaneous driving impairment
Chemical analysis of a collected sweat specimen	An assay result concerning its specified analyte and method	A measurement of cue-induced craving or a direct reading of the person’s subjective state

The Khan review’s SCR discussion concerns the first measurement. It is not a validation study of a sweat patch or a chemical methamphetamine sensor.

Why did food-related control cues matter?

The review summarizes a 2021 study by Guerin and colleagues that included both control stimuli and a methamphetamine-naive comparison group. In that account, people with methamphetamine use disorder showed greater skin-conductance responses and reported craving to methamphetamine cues than to control cues. The comparison group did not show corresponding cue-type differences.

The control material depicted food-related items and activities. The rationale was that food consumption and drug-taking can share visible actions and object use. These controls were intended to improve on comparisons with nature scenes or sexual material, which can themselves differ markedly in arousal.

The choice of comparator therefore helps define the inference. A drug image compared with a calm landscape asks a different question from a drug image compared with another activity involving meaningful objects. Food cues are not a guarantee that every relevant characteristic has been matched. They are a design choice intended to make the comparison more informative.

Does the comparison establish a diagnostic cutoff?

No individual diagnostic rule follows from the review’s description. A reported difference between groups or cue conditions does not identify a conductance value that reliably classifies one person. It also does not provide diagnostic sensitivity, specificity or a false-positive rate for a forensic use that was not validated.

There is a further statistical boundary: describing one group’s difference and another group’s null finding is not, by itself, a substitute for inspecting the formal interaction analysis in the primary paper. This commentary relies on the review’s narrative account and does not supply an independently verified interaction estimate, sample denominator or effect size for that underlying experiment.

The distinction keeps the evidence proportionate. The described pattern supports investigation of learned cue responses, while leaving individual classification as a separate validation question.

Did the response reconstruct methamphetamine exposure?

The review reports an association between longer methamphetamine-use history and stronger physiological cue reactivity. It also describes greater physiological cue reactivity among people reporting intravenous use than among those reporting smoking.

These are historical group associations. They are not a controlled comparison assigning equal known doses by different routes. Neither a duration association nor a route-group difference can be turned into a formula for an individual’s dose, product purity, time of last use or specimen concentration.

The review proposes bioavailability and conditioning as possible explanations for these patterns. The proposal does not establish which mechanism produced a particular person’s response, and a stronger physiological signal does not chemically identify what they consumed.

Can craving or cue reactivity predict relapse with certainty?

No. The review connects cue reactivity, inhibitory control and relapse risk as part of its broader explanatory framework. It describes self-reported cue-induced craving as negatively associated with inhibitory control. An association among research measures is different from a validated forecast of whether and when an individual will return to use.

The same caution applies to the review’s gene–cognition model. A pathway linking genetic predisposition, inhibitory control and repeated use is a hypothesis about interacting processes. It is not a finding that a conductance response proves a particular genotype, diagnosis or future act.

What is the useful forensic distinction?

Identify the measurement before interpreting the number. If the instrument recorded skin conductance during a cue task, describe physiological cue reactivity. If a laboratory assayed a sweat specimen, identify the analyte, specimen and analytical procedure. If a participant rated craving, preserve that subjective endpoint.

None of those labels can replace the others. The reviewed cue evidence does not prove acute methamphetamine exposure, establish impairment from drug presence, or determine a person’s state of mind during an unrelated event.

Scientific source

Khan R, Turner A, Berk M, et al. Genes, Cognition, and Their Interplay in Methamphetamine Use Disorder. Biomolecules. 2025;15(2):306. doi:10.3390/biom15020306. Full-text review. Historical narrative review, especially sections 4.2 and 5. The underlying 2021 cue study is discussed through this review, rather than presented as an independently examined primary source.

Whole-blood calibrators can support quantitative work in alternative autopsy matrices when the complete procedure is evaluated, but an internal standard does not guarantee equal accuracy everywhere. A six-matrix benzodiazepine study reported generally acceptable performance alongside midazolam muscle bias near positive 30% and flunitrazepam negative bias up to 24%.

Why the investigators used one calibration matrix

Øiestad and colleagues analyzed peripheral blood, cardiac blood, pericardial fluid, psoas muscle, lateral vastus muscle and vitreous humor. Their selected case series contained 109 benzodiazepine- or z-hypnotic-positive cases from 183 project autopsies performed during June 2013–November 2016.

Calibrators and routine quality controls were prepared in whole blood obtained from a blood bank. The authors identified the use of whole-blood calibration for all six matrices as a limitation and said dedicated matrix calibrators would have been preferred. Restrictions on obtaining alternative matrices from routine cases constrained that approach.

They did not simply assume that blood calibration transferred correctly. Negative material from project cases was used to investigate matrix effects, extraction recovery, accuracy and precision in the alternative matrices.

Matrix effects and recovery were different tests

Matrix effects were evaluated at two concentration levels using specimens from five autopsy cases. Post-extraction-spiked samples were compared with neat standards; separately, samples spiked before extraction were compared with post-extraction-spiked samples to assess recovery.

Some ion suppression was observed, particularly in muscle. The authors reported that internal-standard correction addressed the observed suppression, with matrix-effect coefficients of variation below 15%. Extraction recovery was lower for several compounds in muscle. Recovery CVs were below 20%, except for diazepam in peripheral blood, where the reported CV was 26%.

Correcting ion suppression and obtaining consistent recovery are therefore not the same claim. Neither result by itself establishes that the complete concentration measurement has negligible bias.

The accuracy exceptions should remain visible

Most spiked-matrix QC results met the paper’s stated ±20% performance criterion. However, flunitrazepam showed systematic negative bias up to −24%, while midazolam muscle samples had positive bias close to 30%. A deviating low-level diazepam QC sample also affected precision and accuracy in peripheral blood, cardiac blood and pericardial fluid.

The main paper reported these exceptions alongside its overall favorable conclusion. Those analyte-specific findings limit how broadly the overall validation result can be applied: performance differed by compound and matrix.

The authors suggested that carbon-13-labeled standards might improve the affected measurements compared with deuterated standards. That was a proposed improvement, not a demonstrated correction tested in this case series.

Analytical performance did not validate a biological conversion

Specimens were collected at autopsy, generally within a week of death, then refrigerated at 4°C after laboratory arrival, typically for one to two weeks. Muscle was homogenized and dilution-corrected. Matrices from the same case were analyzed together as far as possible to reduce storage and instrument variation.

Even a successful calibration transfer would describe concentration in the collected specimen. It would not make muscle equivalent to femoral blood, reverse redistribution or establish a concentration during life. No antemortem comparison samples were available.

What a laboratory review should preserve

Identify the calibrator matrix, analyte-matched performance data, internal standard, recovery, matrix effects, bias and precision. Distinguish fortified QC experiments from authentic case measurements. Neither a well-fitted curve nor a positive drug result independently establishes impairment or cause of death.

For another calibration strategy and its limits, see standard addition in postmortem tissues.

Primary source

Øiestad EL, Øiestad ÅML, Middelkoop G, Brochmann GW, Thaulow CH, Vindenes V. Comparative Study of Postmortem Concentrations of Benzodiazepines and Z-Hypnotics in Several Different Matrices. Journal of Analytical Toxicology. 2023;47:287–298. doi:10.1093/jat/bkac106.

Diluting postmortem muscle for analysis can determine which low drug concentrations enter a published comparison. In one six-matrix study, investigators first compared the muscle-homogenate measurement with the quantitation limit and only then corrected qualifying results for dilution. That sequence matters when fewer muscle findings are interpreted as evidence of absent exposure.

What material was studied?

Øiestad and colleagues included 109 benzodiazepine- or z-hypnotic-positive autopsies from a 183-case specimen project. Samples were collected from June 2013 through November 2016, generally within one week after death.

The study paired peripheral and cardiac blood with pericardial fluid, psoas muscle, lateral vastus muscle and vitreous humor. Peripheral blood was expressed from femoral vessels after iliac-vein transection and cessation of initial flow. Samples remained at 4°C after laboratory arrival, typically for one to two weeks before project analysis.

A tissue result and a homogenate result are different measurements

Muscle preparation used approximately 3.5 g of tissue with 14 mL water. The investigators corrected measured homogenate concentrations using the actual tissue weight and added water. Under the study’s calculation, the nominal preparation produces approximately fivefold dilution.

The final muscle results were reported per tissue mass, in mg/kg, while blood and fluid results were in mg/L. A number measured in diluted homogenate should not be compared directly with a blood concentration before the preparation and unit conversion are considered.

The authors explicitly stated that muscle-homogenate measurements were evaluated against the quantitation limit first. Only values exceeding that limit were corrected for dilution and included. Mathematical correction did not rescue an excluded low measurement into the reported dataset.

An illustrative threshold shows why sequence matters

The confirmation-method quantitation limit listed for diazepam was 0.0071 mg/L. With an exactly fivefold preparation, the corresponding numerical threshold after correction would be approximately 0.0355 mg/kg of original muscle. This is an illustration using the paper’s preparation convention, not a newly validated tissue limit or a universal threshold for every muscle sample.

Actual dilution depended on the weighed tissue. The calculation also did not establish a detection limit. A specimen that failed the quantitative inclusion rule was not thereby proof that no diazepam was present.

What did the authors observe?

The paper reported fewer findings in muscle and considered dilution during homogenization a possible explanation. Missing muscle values became more frequent as peripheral-blood concentrations decreased. That was an interpretation of casework patterns, not a controlled experiment measuring how many findings dilution alone removed.

For diazepam, Table II listed 38 peripheral-blood findings, 30 psoas findings and 27 lateral-vastus findings. Their reported concentration medians were 0.15 mg/L, 0.14 mg/kg and 0.17 mg/kg. These different positive subsets cannot be treated as three interchangeable population distributions.

Analytical validation and study selection both matter

Routine screening and separate confirmation used UHPLC–MS/MS procedures. Whole-blood calibrators were used for all matrices, with separate alternative-matrix performance checks. The study selected cases through peripheral-blood findings, so it did not measure muscle screening sensitivity in all possible exposed decedents.

Most bodies had no or slight putrefaction; only four had moderate putrefaction. The results do not establish the same performance in severe decomposition or burns.

For case review, preserve the muscle site, tissue weight, dilution, measured homogenate result, reporting rule and corrected units. Neither an omitted low result nor a corrected positive concentration independently establishes dose, impairment or cause of death. See also matrix-dependent clonazepam parent/metabolite relationships.

Primary source

Øiestad EL, Øiestad ÅML, Middelkoop G, Brochmann GW, Thaulow CH, Vindenes V. Comparative Study of Postmortem Concentrations of Benzodiazepines and Z-Hypnotics in Several Different Matrices. Journal of Analytical Toxicology. 2023;47:287–298. doi:10.1093/jat/bkac106.

Pericardial fluid can support postmortem diazepam testing when peripheral blood is unavailable, but a strong correlation does not make the two specimens interchangeable. In a Norwegian study, 37 paired diazepam results had pericardial-fluid/peripheral-blood ratios from 0.30 to 7.3, despite a significant positive correlation between the matrices.

Which cases and specimens were compared?

Øiestad and colleagues collected six matrices during medicolegal autopsies from June 2013 through November 2016. Of 183 project cases, 109 had a benzodiazepine or z-hypnotic finding and entered this investigation. Not all 109 involved diazepam.

The matrices were peripheral blood, cardiac blood, pericardial fluid, psoas muscle, lateral vastus muscle and vitreous humor. Autopsies generally occurred within a week of death. After laboratory arrival, material was refrigerated at 4°C, typically for one to two weeks while peripheral-blood screening was completed.

Peripheral blood was femoral blood expressed after iliac-vein transection and cessation of initial flow. Collection often used both sides to obtain 40–50 mL. Thus, the blood reference was a specified postmortem collection, not a sample taken during life.

Preserve the paired result rather than dividing group medians

Table II reported diazepam concentrations above quantitation limits in 38 peripheral-blood samples and 40 pericardial-fluid samples. Their medians were 0.15 and 0.18 mg/L, respectively. These groups were not identical to the 37 pairs used for the ratio summary.

Table III gave a median paired pericardial/blood ratio of 1.7, with the range 0.30–7.3. Dividing the two concentration medians would produce a different number. It would not reproduce the median of individual paired ratios.

The Spearman correlation for pericardial fluid against peripheral blood was 0.81 and significant at the 0.01 level. This supports an association in the ordering of concentrations. It does not establish equal results, narrow individual prediction limits, or equivalence within a specified margin.

The relationship also depended on the compound

For parent clonazepam, 47 pericardial/blood pairs had a median ratio of 0.64 and range of 0.030–19. For 7-aminoclonazepam, the median was 1.1 across 62 pairs, with a range of 0.25–8.5. A general pericardial-fluid conversion factor would obscure these drug-specific patterns and individual outliers.

These are ratios between two postmortem measurements. They did not quantify how much either concentration changed after death, and no antemortem concentrations were available to identify which specimen best represented the level during life.

Analytical support did not eliminate biological variation

Routine screening and separate confirmation used UHPLC–MS/MS methods. The diazepam confirmation quantitation limit was 0.0071 mg/L. Results below the relevant limits were excluded from evaluation. All matrices used whole-blood calibration, with additional matrix-effect, recovery, accuracy and precision checks.

The authors described a deviating low-level diazepam QC sample affecting precision and accuracy in peripheral blood, cardiac blood and pericardial fluid. Analytical performance therefore belongs alongside the casework comparison rather than being assumed uniform across every result.

What can be concluded in a new death investigation?

Pericardial fluid is a useful alternative specimen, but its result should retain its own matrix identity and units. The study did not validate a lethal concentration, establish impairment or provide an exact missing-blood reconstruction.

For a different analytical question, see pericardial fluid versus urine for benzodiazepine screening. A screening comparison does not supply quantitative blood equivalence.

Primary source

Øiestad EL, Øiestad ÅML, Middelkoop G, Brochmann GW, Thaulow CH, Vindenes V. Comparative Study of Postmortem Concentrations of Benzodiazepines and Z-Hypnotics in Several Different Matrices. Journal of Analytical Toxicology. 2023;47:287–298. doi:10.1093/jat/bkac106.