Neuroimaging and ADHD: fMRI, PET, DTI findings, and methodological limitations.

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by pervasive and developmentally inappropriate levels of inattention, impulsivity, and hyperactivity. There is no conclusive cause of ADHD although a number of etiologic theories have been advanced. Research across neuroanatomical, neurochemical, and genetic disciplines collectively support a physiological basis for ADHD and, within the past decade, the number of neuroimaging studies concerning ADHD has increased exponentially. The current selective review summarizes research findings concerning ADHD using functional magnetic resonance imaging (fMRI), positron emission tomography (PET), and diffusion tensor imaging (DTI). Although these technologies and studies offer promise in helping to better understand the physiologic underpinnings of ADHD, they are not without methodological problems, including inadequate sensitivity and specificity for psychiatric disorders. Consequently, neuroimaging technology, in its current state of development, should not be used to inform clinical practice.

The relationship between ADHD symptomology and decision making.

OBJECTIVE: To explore the relationship between the symptoms of ADHD, the extent to which college students seek to maximize their decisions, and the degree to which students feel regret for their decisions. METHOD: Undergraduate students (N = 275) completed four questionnaires measuring ADHD symptomology, internal restlessness, maximization tendencies, and regret. It was hypothesized that (a) participants who reported more behaviors associated with ADHD and internal restlessness would report more maximizing tendencies, (b) participants reporting greater ADHD symptoms and internal restlessness symptoms would be more likely to report feelings of regret, (c) men would report more symptoms of ADHD and internal restlessness than women, and (d) men would be more likely to report maximization tendencies than women. RESULTS: Findings supported the hypotheses and interaction were found. CONCLUSIONS: Findings provided new information concerning relationships between ADHD symptomology, internal restlessness, maximization tendencies, and regret.

Double-blind, placebo-controlled, crossover study of the efficacy and safety of lisdexamfetamine dimesylate in college students with ADHD.

OBJECTIVE: To evaluate stimulant medication on symptoms and functioning for college students with ADHD using double-blind, placebo-controlled, crossover design. METHOD: Participants included 24 college students with ADHD and 26 college students without psychopathology. Lisdexamfetamine dimesylate (LDX) was examined for ADHD participants over five weekly phases (no-drug baseline, placebo, 30-, 50-, and 70-mg LDX per day). Self-report rating scales of functioning and direct assessment of ADHD symptoms, verbal learning/memory, and adverse side effects were collected (baseline only for control students). RESULTS: LDX was associated with large reductions in ADHD symptoms and improvement in executive functioning along with smaller effects for psychosocial functioning. Reduction in ADHD symptoms was found for 86.4% of participants; however, large differences in symptoms and executive functioning remained relative to controls. CONCLUSION: LDX is a safe, efficacious treatment for symptom relief in college students with ADHD. Research documenting medication effects on academic functioning and evaluating psychosocial/educational interventions is needed.