Physiological substrates of executive functioning: a systematic review of the literature.

Executive function (EF) is a multifaceted construct that has been defined as a set of higher-order cognitive processes that allow for flexibility, self-regulation, strategic planning, and goal-directed behaviors. EFs have been studied in numerous clinical disorders using a variety of neuropsychological tasks and, more recently, neuroimaging techniques. The underlying physiological substrates of EF were historically attributed to the frontal lobes; however, recent studies suggest more widespread involvement of additional brain regions. The purpose of the present study was to conduct a systematic review (using PRISMA 2009 guidelines) of neuroimaging studies employing functional magnetic resonance imaging and diffusion tensor imaging methods investigating the physiological substrates of EFs in attention-deficit/hyperactivity disorder compared to other clinical groups and non-clinical participants. Research articles were retrieved using PsycINFO, PsycARTICLES, MEDLINE, and ScienceDirect, beginning February 2015 through May 2016. A total of 42 studies met eligibility. Of those 42 studies, 22 studies included clinical participants and 20 studies included non-clinical participants. Results revealed increased activation of the frontal brain region in the majority of non-clinical studies and approximately 50% of the clinical studies, albeit with some inconsistencies across subregions, tasks, and age groups. Implications, methodological limitations, and suggestions for future research are discussed.

The relationship between nonmedical use of prescription stimulants, executive functioning and academic outcomes.

The nonmedical use of prescription stimulants (NMUPS) is a prevalent issue among college students. The primary reason college students report NMUPS is for academic enhancement i.e., to perform better on schoolwork/tests and focus better in class. Executive functioning (EF), which includes abilities that allow for planning, cognitive flexibility, self-regulation, and goal-directed behavior, are potential mechanisms underlying academic performance. Preliminary research has revealed that college students with EF deficits are more likely to have educational difficulties and take part in risky behavior. Based on the literature, it is possible that students with EF deficits are engaging in NMUPS to help them overcome these deficits to succeed academically. Therefore, the purpose of the present study was to examine the relationship between NMUPS and EF among a sample of college students. The sample included 308 students from six public universities located in various regions of the United States. Measures used in this study were the SSQ, BDEFS and GPA. Results revealed 18.8% of the general sample reported NMUPS. Participants with clinically significant EF deficits reported significantly higher rates of NMUPS, compared to those without deficits in EF. NMUPS, however, did not moderate the relationship between EF and GPA. The present findings have implications for identifying sub-populations of college students who might be at risk for engaging in NMUPS and to improve prevention and intervention strategies aimed at reducing NMUPS. Limitations and suggestions for future research are discussed.

Prescription stimulant medication misuse: Where are we and where do we go from here?

Prescription stimulants, including methylphenidate (e.g., Ritalin) and amphetamine compounds (e.g., dextroamphetamine; Adderall), have been approved by the U.S. Food and Drug Administration for the treatment of attention-deficit/hyperactivity disorder (ADHD) and are classified by the United States Drug Enforcement Administration as Schedule II medications because of their high potential for abuse and dependence (Drug Enforcement Administration, U.S. Department of Justice, 2015). Despite the potential health and judicial consequences, misuse of prescription stimulants, typically defined as taking stimulants without a valid prescription, or use of stimulants other than as prescribed, has become a serious problem in the United States and abroad, especially on college campuses. The purpose of the present article is to review historical information concerning prescription stimulants and to summarize the literature with respect to misuse among adults, particularly college students, including risk factors, mediators and moderators, and motivations for prescription stimulant misuse. In addition, evidence is presented concerning the question of whether prescription stimulants truly enhance cognitive functioning in individuals with and without ADHD, and the ethical and professional implications of these findings are explored. Lastly, recommendations for addressing prescription stimulant misuse and suggestions for future research are advanced. (PsycINFO Database Record

Pharmacological interventions for adolescents and adults with ADHD: stimulant and nonstimulant medications and misuse of prescription stimulants.

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by symptoms of inattention, hyperactivity, and impulsivity that cause functional impairment. Recent research indicates that symptoms persist into adulthood in the majority of cases, with prevalence estimates of approximately 5% in the school age population and 2.5%-4% in the adult population. Although students with ADHD are at greater risk for academic underachievement and psychosocial problems, increasing numbers of students with ADHD are graduating from high school and pursuing higher education. Stimulant medications are considered the first line of pharmacotherapy for individuals with ADHD, including college students. Although preliminary evidence indicates that prescription stimulants are safe and effective for college students with ADHD when used as prescribed, very few controlled studies have been conducted concerning the efficacy of prescription stimulants with college students. In addition, misuse of prescription stimulants has become a serious problem on college campuses across the US and has been recently documented in other countries as well. The purpose of the present systematic review was to investigate the efficacy of prescription stimulants for adolescents and young adults with ADHD and the nonmedical use and misuse of prescription stimulants. Results revealed that both prostimulant and stimulant medications, including lisdexamfetamine dimesylate, methylphenidate, amphetamines, and mixed-amphetamine salts, are effective at reducing ADHD symptoms in adolescents and adults with ADHD. Findings also suggest that individuals with ADHD may have higher rates of stimulant misuse than individuals without the disorder, and characteristics such as sex, race, use of illicit drugs, and academic performance are associated with misuse of stimulant medications. Results also indicate that individuals both with and without ADHD are more likely to misuse short-acting agents than long-acting agents. These findings have implications for intervention, prevention, and future research.

Misuse of prescription stimulants among college students: a review of the literature and implications for morphological and cognitive effects on brain functioning.

Prescription stimulant medication, the most frequently recommended treatment for college students with attention deficit/hyperactivity disorder (ADHD), has become increasingly available on college campuses. Research investigating prescription stimulant misuse among college students indicates that significant numbers of students without ADHD are taking prescription stimulants to enhance their cognitive performance. This article systematically reviews studies concerning misuse of prescription stimulants among college students with and without ADHD as well as the cognitive and morphological brain changes associated with prescription stimulants in humans and other animals. Whether these morphological changes are accompanied by improved cognitive performance remains equivocal. Implications of this body of literature are discussed and suggestions for future research are advanced.