Browse every published article, from the latest research to earlier analysis. Use the page numbers below to explore the complete archive.
Does a Parkinsonian-Like Test Pattern Diagnose Parkinson Disease After Methamphetamine Use? No. A Parkinsonian-like pattern on a cognitive task is not a diagnosis of Parkinson disease. A 2026 study used that comparison to describe selected test differences in recently abstinent methamphetamine users, without establishing their future disease risk. The task and the sample Dumitrescu and…
Methamphetamine Abstinence: Response Inhibition Is Different From Risk Taking Recently abstinent participants with methamphetamine use disorder showed differences in response inhibition without significant differences on two gambling-style risk tasks. The findings argue for naming the specific difficulty rather than labeling all decision-making impaired. Four tasks addressed different constructs Vest and colleagues compared 29 participants recruited…
Sensory Brain Responses and Executive Control in Methamphetamine Dependence A small functional MRI study linked methamphetamine dependence with differences extending beyond executive-control regions into sensory cortex. That broader pattern makes a simple claim about a single damaged control center inadequate. The human comparison Zerekidze and colleagues studied 18 participants with methamphetamine dependence and 21 healthy…
Attention and Impulsive Choice Can Recover Differently During Methamphetamine Treatment A small longitudinal study found improvement in sustained attention during methamphetamine treatment while stronger preference for immediate rewards persisted. Treating cognition as a single ability would conceal that difference. What was followed over time Bernhardt and colleagues recruited 30 methamphetamine-dependent patients and 24 non-substance-abusing comparison…
Does Cognitive Improvement in the First Month of Methamphetamine Abstinence Exceed Practice Effects? Repeated cognitive testing can improve scores even without recovery from drug-related difficulty. A study of early methamphetamine abstinence did not establish significantly greater overall improvement than the change seen in healthy comparison participants. Why a retested comparison group mattered Simon and colleagues…
Can Brain Spectroscopy Measure Stimulant Effects Without Measuring Impairment? Magnetic resonance spectroscopy detected changes in selected brain metabolites after stimulant administration. Those measurements were neither blood drug concentrations nor direct measurements of driving impairment or synaptic neurotransmitter release. A controlled comparison of two different drugs White and colleagues enrolled healthy volunteers in a double-blind crossover…
Why Men and Women Responded Differently on a Methamphetamine Reaction-Time Task In a controlled experiment, methamphetamine shortened reaction times in women but did not significantly shorten them in men. The result was not a general demonstration that the drug improved reward-based decision-making. The experiment and its participants Mayo and colleagues analyzed task data from 44…
Feeling Better and Working Harder After Methamphetamine Are Different Outcomes Methamphetamine increased willingness to choose a demanding reward task, but those changes were not related to the participants’ increases in euphoria or drug liking. Feeling more stimulated therefore did not provide a reliable measure of the behavioral change in this experiment. What participants actually chose…
Does Methamphetamine Change Anticipation of Loss More Than Reward? A controlled human experiment found that methamphetamine changed selected brain responses while participants anticipated losing money. It did not produce a uniform increase in responses to rewards, and the imaging findings do not establish impaired judgment in an individual. A task separating anticipation from outcome Molla…
Why a Quantifiable Amphetamine Result Is Not an Impairment Scale: The Swedish Driver Study A blood laboratory’s ability to quantify amphetamine does not establish how impaired a driver was. In a Swedish observational study, amphetamine concentrations overlapped substantially across physician-rated impairment categories. The study is particularly useful for separating an analytical reporting limit from a…
A placebo-controlled study of racemic d,l-methamphetamine found no statistically significant overall driving difference under its experimental conditions. That finding should retain its formulation and should not be treated as a direct head-to-head comparison with pure d-methamphetamine. What the racemic experiment tested Silber and colleagues studied 20 recreational stimulant users who received oral d,l-methamphetamine at 0.42…
Years of schooling were an imperfect proxy for cognitive ability in a study of methamphetamine dependence. Simply adjusting for education can therefore change an analysis without necessarily removing the influence researchers intend to control. Education can reflect more than baseline ability Dean and colleagues evaluated 36 methamphetamine-dependent participants and 42 healthy comparisons with cognitive testing…
Methamphetamine-dependent participants showed more variable response timing during a vigilance task, and variability was associated with poorer functional outcomes. Average response speed alone did not capture this pattern. What intraindividual variability measured Morgan and colleagues compared 35 methamphetamine-dependent participants with 55 comparison participants. They analyzed fluctuations within a person’s responses across a continuous performance task,…
Adults in remission from methamphetamine addiction reported executive and impulsivity problems alongside objective task differences. The findings challenge the assumption that people with such difficulties necessarily lack awareness of them, while leaving individual insight to be assessed directly. Self-report and laboratory measures together Ellis and colleagues compared 30 adults in remission with 24 demographically matched…
A structural MRI study found a larger right putamen in active methamphetamine-dependent participants, with greater volume associated with fewer errors on a response-inhibition task. Brain size differences did not support a simple rule that enlargement proves either damage or improved overall function. What the study measured Jan and colleagues compared 17 active methamphetamine-dependent participants with…
Manipulating a brainstem neuronal population reduced methamphetamine-associated attention deficits in male rats. This is mechanistic animal evidence, not proof of a treatment for humans or an impairment threshold for drivers. The experimental model Qu and colleagues used repeated passive methamphetamine injections in rats and assessed attention with the five-choice serial reaction time task. The researchers…
Methamphetamine altered visual scanning during simulated highway driving without impairing the study’s vehicle-control measures. Preserved lane or steering performance therefore did not mean that every measured driving-related process was unchanged. Eye tracking added an outcome beyond lane keeping Hayley and colleagues studied 20 healthy adults in a randomized, double-blind, placebo-controlled crossover experiment. Participants completed four…
Active methamphetamine users discounted outcomes more strongly across future, past, probability and social-distance tasks than comparison participants. The study addresses how outcomes are valued, rather than proving a universal inability to understand consequences. Four dimensions of psychological distance Yi and colleagues compared active users with nonusing controls using behavioral-economic tasks. Future and past discounting examined…
Former methamphetamine users responded more slowly on a flanker task, but did not show larger conflict or sequential-adjustment effects than matched controls. General slowing and impaired conflict resolution were different findings in this experiment. What the task tested Bensmann and colleagues compared 24 abstinent former users with 24 individually matched controls in a cross-sectional human…
ADHD was more common among participants with methamphetamine use disorders and was independently associated with everyday functional difficulties. That finding makes developmental history relevant; it does not establish that methamphetamine caused ADHD or that every reported difficulty came from drug exposure. A large observational comparison Obermeit and colleagues studied 400 participants with methamphetamine use disorders…
Poorer neurocognitive performance was associated with unemployment among participants with recent methamphetamine dependence. The study supports evaluating cognitive function in vocational assessment, but it does not show that every person with a use history is unable to work. The study measured employment and cognition together Weber and colleagues evaluated 63 participants with recent methamphetamine dependence…
People with longer methamphetamine abstinence showed less Stroop interference than recently abstinent participants in a pooled human study. The result suggests possible improvement in cognitive control, but does not prove that each individual recovers on a fixed timetable. Different abstinence groups, not repeated recovery measurements Salo and colleagues compared 38 recently abstinent participants, 27 abstinent…
Attention deficits associated with methamphetamine-dependence history were no longer statistically significant after researchers excluded participants with positive methamphetamine urine screens. This sensitivity analysis changes how the results can be described: dependence history and evidence of recent use were not interchangeable. The four-group human comparison Pocuca and colleagues enrolled 205 participants classified by HIV status and…
Abstinent methamphetamine-dependent participants had difficulty rearranging digits into order in a controlled task comparison, while performance on an already ordered condition did not show the same group difference. The finding concerns manipulation of information, rather than an undifferentiated loss of all memory. How the comparison separated two memory demands Yao and colleagues compared 62 abstinent…
Methamphetamine’s effects on perceived control did not follow a simple all-or-nothing pattern in a controlled experiment. A low intranasal dose improved a task-specific judgment of agency, while higher doses increased certain errors under difficult conditions without globally disrupting control judgments. What judgment of agency meant in this experiment Kirkpatrick and colleagues studied ten adults with…
A controlled trial found that methamphetamine attenuated several low-dose alcohol effects on laboratory cognition and sustained subjective stimulation. It did not establish that the combination is safe, that alcohol had been eliminated, or that participants could drive normally. Four conditions in the same volunteers Hayley and colleagues studied 16 healthy adults across four experimental sessions:…
Intravenous methamphetamine produced mild psychotic-like symptoms in a small controlled experiment, but did not significantly change how much evidence participants gathered before a decision on a beads task. Symptoms and information gathering were separate measured outcomes, and their results should remain separate. A task designed to measure information gathering Ermakova and colleagues analyzed 17 healthy…
A Norwegian registry study found a modest positive association between blood amphetamines and physician-assessed impairment among suspected drugged drivers. It did not establish a methamphetamine-only impairment threshold or a rule that diagnoses every individual driver. The population was selected before the analysis Gustavsen and colleagues examined 878 registry cases in which amphetamine and/or methamphetamine were…
Standardized field sobriety tests did not significantly distinguish d-methamphetamine from placebo in a controlled study of 58 recreational drug users. That result concerns the sensitivity of specific tests under defined conditions. It does not prove that every participant was safe to drive. What was actually administered and tested? Downey and colleagues used a double-blind, within-subject,…
A 30-driver study found differences in speeding, lane position and turning gaps, but did not establish that blood methamphetamine predicts individual impairment.