Psychostimulant can improve concentration in the short term but prevents sleep and mental functions based on it

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The use of prescription stimulants by those without medically diagnosed conditions marks a growing trend among young adults – particularly college students seeking a brain boost.

But according to a study led by the University of California, Irvine, taking a nonprescribed psychostimulant may slightly improve a person’s short-term focus but impede sleep and mental functions that rely on it – such as working memory.

“Healthy individuals who use psychostimulants for cognitive enhancement may incur unintended costs to cognitive processes that depend on good sleep,” said lead author Lauren Whitehurst, a former graduate student in UCI’s Sleep and Cognition Lab who’s now a postdoctoral fellow at the University of California, San Francisco.

“Our research shows that while psychostimulants may mildly curb natural attentional deterioration across the day, their use also disturbs sleep and post-sleep executive function.”

The study, conducted in the Sleep and Cognition Lab, involved 43 people between 18 and 35 years old.

Before receiving any medication, they completed baseline working memory and attention tasks.

For the latter, participants had to track several moving circles on a screen for a short period of time.

For working memory, they were asked to remember and manipulate a set of letters while performing simple math equations and then after a short retention interval, recall all the letters.

In one subsequent 9 a.m. lab visit, subjects were given an inactive placebo pill; in another, they got 20 milligrams of dextroamphetamine – a drug in the same class of psychostimulants as Adderall.

At 75-minute and 12- and 24-hour intervals after each dose, participants repeated the attention and working memory tasks – spending the night in private rooms in the lab, where their brain activity was measured via electroencephalography.

“Our research suggests that the purported enhancement to executive function from psychostimulants in healthy populations may be somewhat exaggerated, as we found only minor daytime improvement in attention and no benefit to working memory,” said co-author Sara Mednick, UCI associate professor of cognitive sciences and director of the campus’s Sleep and Cognition Lab.

“In addition, we noted a large impairment to nighttime sleep, even though the medication was administered in the morning.

Psychostimulants also led to detrimental consequences to cognitive functions that rely on good sleep.

Thus, people who are taking these drugs to perform better in school or at work may feel as though they are doing better, but our data don’t support this feeling.”

Her team discovered that attentional performance deteriorated throughout the day whether subjects received the dextroamphetamine or the placebo – an important finding that may help guide future studies on attention.

Researchers also determined that when participants ingested dextroamphetamine, they did about 4 percent better on the attentional task 75 minutes later than did the placebo group – and than they themselves had done during baseline testing.

This small boost was not reflected in the 12- or 24-hour test, after sleep.

For working memory, on the other hand, subjects who had taken the stimulant performed the same as those who had taken the placebo on the 75-minute and 12-hour tests. But 24 hours after ingestion, the dextroamphetamine group did markedly worse on the test than did the placebo group, and overnight EEG and polysomnography measurements showed significant reductions in total sleep time and quality for those given the stimulant.

The working memory findings have been published online in Behavioural Brain Research.


International media has paid attention to the use of substances by healthy subjects to enhance cognitive performance. Medical students are liable to use cognitive enhancers (CE) with the aim of improving academic performance.

The study explored use and attitudes toward the use of CE in Italian medical students. The authors anonymously surveyed 433 medical students of the University of Modena and Reggio Emilia with an ad hoc 36-items questionnaire.

CE were broadly defined as any substance taken with the purpose of improving cognitive functions, from readily available beverages and substances, such as coffee, tea, energy drinks, and supplements to prescription only medication, such as psychostimulants and modafinil. Response rate was 83.8% (n = 363).

While the majority of the students (74.7%; n = 271) said that they had used substances to improve cognitive functions, only 2 students (0.6%) reported the use of prescription-only medications in the last 30 days.

Main reasons for not taking prescription-only drugs were concerns about safety and side effects, reported by 83.3% of students (n = 295). A positive attitude toward use was held by 60.3% (n = 219) subjects.

The surveyed Italian medical students used many substances as CE, but this did not seem to apply significantly to psychostimulants.

A multivariable analysis showed that the following variables were related to the propensity to use substances as CE: male gender, self-reported memory impairment, concerns about worsening of cognitive performance, lifetime use of at least one illegal substance, use of any substance (both legal or illegal) in the last 30 days.

The term cognitive enhancement (CE) refers to strategies that are thought to improve cognitive performance and thereby to confer an advantage in certain situations [1].

Cognitive enhancers may be readily available substances, such as caffeine and energy drinks, as well as psychostimulants, when used with the aim at improving cognitive functions.

It is reported that healthy subjects increasingly resort to use prescription-only medication – especially psychostimulants used to treat attention deficit hyperactivity disorder (e.g., methylphenidate, amphetamine, atomoxetine) and modafinil – with the purpose of enhancing their cognitive performance [2,3].

Recent studies have linked the use of cognitive enhancers to high levels of stress related to performance in populations of college students, including medical students [4,5].

The latter seems a population liable to use cognitive enhancers.

In fact, the prevalence of use reported in this population is around 15% in recent studies [4,6].

Moreover, the attention paid by international mass media to this phenomenon is steadily increasing [7].

The attitude toward the use of cognitive enhancers also varies widely in published studies.

For example, in one study, 2 out of 3 participants stated that under no circumstances would they use a cognitive enhancer [8].

Alternatively, another study reported a positive attitude toward its use in 90.6% of the subjects enrolled [9].

Little is known about the use and attitudes to use of cognitive enhancing substances among Italian students.

In 2012, 34 medical and nursing students and 44 students of other courses attending a Public Health University Degree in Milan, Italy were surveyed [10].

Subjects were not requested to specify which drug they had used. Researchers found that 12% of the medical sample and 16% of the whole sample had taken drugs to enhance their cognitive functions.

This rate is not confirmed by a recent cross-sectional study conducted at the University of Verona, Italy [11], showing that among medical students, stimulants use increased from the first academic year (2.9%) to the third (6.5%), and then decreased during the fifth year (1.7%).

Such variations may be partly due to the different definitions adopted by each study to define the non-medical use of prescription-only medication. Moreover, such contrasting findings may be a consequence of not specifying the exact substances considered.

Therefore, given the methodological diversity, as well as the different purposes for these surveys, results are difficult to compare. For the sake of comparability, it was suggested that future surveys exploring the use of cognitive enhancers should contain a clear definition of which substances are considered cognitive enhancers [3].

The primary aim of this research was to obtain a better estimate of the prevalence of use and attitudes toward the use of psychostimulants and other substances and nutrients with the purpose of CE among a sample of Italian medical students.

The secondary aim was to assess factors associated with the use of CE in this population.


More information: Tenzin Tselha et al. Morning stimulant administration reduces sleep and overnight working memory improvement, Behavioural Brain Research (2019). DOI: 10.1016/j.bbr.2019.111940

Journal information: Behavioural Brain Research
Provided by University of California, Irvine

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