Browse every published article, from the latest research to earlier analysis. Use the page numbers below to explore the complete archive.
People using prescription stimulants for enhancement reported benefits in energy and motivation at least as strongly as benefits in cognition. A survey of perceived effects cannot determine whether their objective performance actually improved. New survey data alongside a literature discussion Ilieva and Farah presented original survey results from 40 university undergraduates without a self-reported ADHD…
People who scored higher in sensation seeking worked more for d-amphetamine under a laboratory reinforcement procedure. That behavioral outcome is related to, but distinct from, reporting that a drug feels pleasant. Sampling a dose before making a choice The study compared ten high sensation seekers with ten low sensation seekers matched on several characteristics. Participants…
A pharmacogenetic imaging study found that amphetamine’s effects depended on both COMT genotype and working-memory load. A drug response that appeared favorable under one condition could be absent or unfavorable under another. A working-memory challenge during imaging Mattay and colleagues studied healthy volunteers selected according to COMT genotype and other eligibility criteria. They examined prefrontal…
A clinical trial found improved self-reported quality of life with lisdexamfetamine in adults with ADHD and significant executive-function difficulties. Those reports add information about daily experience, while remaining different from objectively measured task performance. A selected clinical population Adler and colleagues examined quality-of-life outcomes from a ten-week randomized placebo-controlled trial. The study randomized 161 adults…
A rat study found dose-dependent attention and short-term-memory decrements after adult d-amphetamine challenges, while adolescent methylmercury exposure alone did not impair those outcomes. The combination of developmental exposure and drug challenge produced a more complex pattern than a single toxicant-effect label. Exposure and testing occurred at different ages Kendricks and colleagues exposed rats to drinking-water…
A four-week trial found that two tested doses of extended-release mixed amphetamine salts improved adult ADHD symptom ratings compared with placebo. Its forced-dose design did not determine the best dose for every participant. The randomized comparison Weisler and colleagues randomized 275 adults to placebo or SHP465 mixed amphetamine salts at 12.5 or 37.5 mg daily.…
A small cognition study described attention-related changes with lisdexamfetamine and immediate-release mixed amphetamine salts, but it did not conduct inferential statistical comparisons. Its findings should not be converted into proof that one formulation was superior. Repeated testing across the day Martin and colleagues used a double-blind, three-period crossover design in adults with ADHD. Participants received…
A controlled imaging comparison found both shared and different network changes after d-amphetamine, LSD and MDMA. Counting altered networks did not provide a simple scale of how psychologically powerful or impairing each drug was. Several connectivity measures Avram and colleagues analyzed resting-state fMRI from a double-blind, placebo-controlled crossover trial involving 28 healthy volunteers. They examined…
A study linked a bacterium and its metabolic product to stronger amphetamine-related behavior through an experimental gene-regulation pathway. The principal behavioral model was the fruit fly, not a clinical trial in people. Which organism was actually tested Mabry and colleagues investigated Fusobacterium nucleatum, the short-chain fatty acid butyrate and histone deacetylase regulation. In gnotobiotic Drosophila,…
A sleep-deprivation experiment found that stimulant benefits depended on the executive task being tested. A drug’s ability to sustain alertness therefore should not be treated as evidence that it restores every higher-order function. Testing after prolonged wakefulness Killgore and colleagues randomly assigned 54 healthy adults to caffeine, 600 mg; modafinil, 400 mg; dextroamphetamine, 20 mg;…
Amphetamine administered during retrieval increased memory errors in a controlled study without increasing the number of correctly remembered items. Memory formation and memory retrieval can respond differently to the same drug. Learning occurred without the drug Ballard, Gallo and de Wit studied 31 healthy young adults. Participants viewed emotional and neutral pictures and words in…
A controlled study found that amphetamine given before viewing pictures strengthened later memory for emotional scenes, while neutral-picture memory did not significantly change. This selective result should not be described as a universal improvement in memory. Separate amphetamine and THC experiments Ballard, Gallo and de Wit studied healthy volunteers in two groups of 25. One…
Four days of atomoxetine reduced selected subjective, blood-pressure and cortisol responses to dextroamphetamine in a small human experiment. That finding does not establish that atomoxetine treats stimulant addiction or prevents harms from uncontrolled stimulant use. What was controlled Sofuoglu and colleagues studied ten healthy volunteers in a crossover design. Participants received atomoxetine, 40 mg daily,…
Dextroamphetamine did not simply increase brain blood flow everywhere in a small PET experiment. Its regional effects depended on which cognitive task participants performed, underscoring the limits of interpreting more activation as universally better function. A task-by-region comparison The study examined eight healthy volunteers using oxygen-15 water PET to measure regional cerebral blood flow. Dextroamphetamine,…
Faster responding can coexist with poorer response control. In a controlled interaction study, d-amphetamine shortened correct-response times while increasing commission errors on a sustained-attention task. Four laboratory conditions The experiment included 12 healthy volunteers, seven men and five women, in a double-blind, placebo-controlled crossover design. Across four sessions, participants received placebo, 20 mg d-amphetamine, 100…
Increased willingness to work for a reward is not the same as learning more effectively from rewards. A controlled d-amphetamine study measured both in the same volunteers and found a selective effect on effort. Two reward-related tasks The study included 30 healthy volunteers who completed testing under placebo and 10- and 20-mg d-amphetamine conditions. The…
A study found that attention-related responses to d-amphetamine differed across COMT genotype groups. The association is evidence about variability in a research sample, not a validated genetic test for predicting an individual’s cognitive response. Genotype and controlled dosing Hamidovic and colleagues studied 161 healthy young adults of European ancestry. Participants received placebo and 10- and…
Background craving and cue-provoked craving showed different patterns across abstinence groups in a methamphetamine study. Lower everyday craving did not necessarily mean a lower response to drug cues at every stage. A comparison across abstinence durations Wang and colleagues compared adults in a rehabilitation center who had been abstinent for periods ranging from days to…
Cognitive flexibility involves more than switching quickly when instructed. A methamphetamine-dependence study compared explicit rule switching with feedback-driven card sorting and found difficulties across both types of demand. Three tasks, different control demands Zhang and colleagues used intra-dimensional switching, extra-dimensional switching and the Wisconsin Card Sorting Test, alongside self-reported cognitive flexibility. Explicitly cued tasks tell…
A comparative study found that methamphetamine and cocaine dependence were associated with larger differences in decision-making than in some other executive functions. Response inhibition did not show the same pattern. The result argues against using “executive impairment” as an undifferentiated label. Four groups and several tasks Van der Plas and colleagues compared 38 methamphetamine-dependent, 27…
Planning and inhibition tests did not tell an identical story in a study comparing current methamphetamine use, abstinence and healthy controls. Some measures distinguished the current-use and abstinent groups; others did not. A three-group battery Farhadian and colleagues studied 161 adults: 41 currently using methamphetamine, 60 abstinent individuals and 60 controls. Participants completed the Tower…
Lisdexamfetamine improved a repeated workplace-style math-performance measure in adults with ADHD across tested times from two to fourteen hours after dosing. That finding concerns a selected clinical population and a defined task, rather than unrestricted enhancement in healthy workers. Dose optimization came before the comparison Wigal and colleagues first used four weeks of open-label dose…
Methamphetamine increased sexual desire in a controlled human study, but it did not significantly change the group’s average hypothetical condom-use decisions. Desire, decision-making and actual behavior are different endpoints. How the experiment separated them Berry and colleagues studied 19 recreational stimulant users in a within-subject, placebo-controlled experiment. Participants received oral placebo, 20 mg methamphetamine and…
Topiramate’s cognitive effects were mixed in a small methamphetamine experiment. Attention-related and psychomotor outcomes did not change uniformly, so neither a simple improvement label nor a simple impairment label captures the findings. A controlled interaction experiment Johnson and colleagues studied ten men and women with methamphetamine dependence. They examined low- and high-dose topiramate conditions, 50…
A controlled reversal-learning study found that methamphetamine altered modeled learning dynamics, with effects depending on baseline performance. That is a more specific result than a general claim that participants made better decisions or earned more points. Learning when reward contingencies change Kirschner and colleagues used a randomized, double-blind, within-subject design. Participants completed a drug-free baseline…
A 2025 preprint reported that methamphetamine changed brain-network signatures related to attention and arousal. It is preliminary primary research, and the version discussed here explicitly states that it was not certified by peer review. Behavior and connectivity were separate outcomes Molla and colleagues used a within-subject, placebo-controlled design involving 20 mg methamphetamine in healthy adults.…
The effects of a methamphetamine–alcohol combination were not constant across repeated administrations in a small residential experiment. Some initially stronger responses diminished by the third administration, making the dosing sequence part of the interpretation. A repeated-exposure design Kirkpatrick and colleagues studied nine adult men in a 20-day within-participant experiment. Four blocks involved oral methamphetamine alone,…
People trained to recognize methamphetamine’s internal effects also responded similarly after d-amphetamine and methylphenidate. That laboratory finding demonstrates overlapping drug cues, not that the substances are chemically identical or interchangeable. What participants learned Sevak and colleagues first trained volunteers to distinguish 10 mg oral methamphetamine from placebo. The discrimination criterion required at least 80% drug-appropriate…
Sleep disruption and next-morning task impairment did not track together in a small controlled intranasal-methamphetamine study. The result does not establish that disrupted sleep is harmless; it shows that different outcomes require separate measurement. Single doses and the following morning Perez and colleagues studied 11 non-treatment-seeking methamphetamine users in a residential, double-blind, within-participant experiment. Separate…
Subjective drug effects are not reliable chemical identification. In a controlled comparison, participants had difficulty distinguishing orally administered methamphetamine from MDMA even though the drugs produced some different effects. A direct comparison in the same volunteers Kirkpatrick and colleagues studied 11 adults during a 13-day residential experiment. Participants received oral methamphetamine at 20 or 40…