ADHD

Additional studies of striatal DA loss in the marmoset also show that this fails to impair extra-dimensional shift performance as affected by prefrontal cortical lesions (Collins et al., 2000). However, the striatal DA loss does produce an impairment in shifting between stimulus dimensions when the requirement is to shift back towards a previously irrelevant dimension, which is possibly relevant to impaired performance of human patients with Parkinson s disease of shifting between two well-established task sets (Cools et al., 2001). 

MODELS OF ATTENTION DEFICIT AND HYPERACTIVITY DEFICIT (ADHD) 

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Pemoline [2152-34-3] (24), stmcturally dissimilar to amphetamine or methylphenidate, appears to share the CNS-stimulating properties. As a consequence, pemoline is employed in the treatment of ADHD and of narcolepsy. There are several other compounds that are stmcturally related to amphetamines, although not as potent and, presumably, without as much abuse potential. These compounds also have anorexic effects and are used to treat obesity. Some of the compounds available are phentermine [122-09-8] fenfluramine [458-24-2] and an agent that is available over-the-counter, phenylpropanolamine [1483815-4] (26). 

The most common treatment of ADHD is pharmacological. Psychostimulant diugs such as methylpheni-date and amphetamine or atomoxetin, an inhibitor of the noradrenaline transporter can be prescribed. These agents elicit the non-exocytotic release of... 

Treatment of attention deficit hyperactivity disorder (ADHD) in children with psychostimulants... 

ADHD because cognitive functions known to be affected in this disorder, namely working memory and inhibitory control, are sensitive to manipulations of D1 receptor-mediated dopamine transmission [1]. Thus, the tonic component might be more critical for the behavioral functions of the FC. 

At low doses, both psychostimulants could theoretically stimulate tonic, extracellular levels of monoamines, and the small increase in steady state levels would produce feedback inhibition of further release by stimulating presynaptic autoreceptors. While this mechanism is clearly an important one for the normal regulation of monoamine neurotransmission, there is no direct evidence to support the notion that the doses used clinically to treat ADHD are low enough to have primarily presynaptic effects. However, alterations in phasic dopamine release could produce net reductions in dopamine release under putatively altered tonic dopaminergic conditions that might occur in ADHD and that might explain the beneficial effects of methylphenidate in ADHD. 

Finally, the cerebellum has recently become a focus of interest in the context of the pathophysiology of ADHD and as a possible target for psychostimulants since it is not only important for motor coordination but also for processing cognitive situations. 

The main indication for certain psychostimulants is ADHD in children and adults [4]. Recent research shows that the clinical effect and benefit are dramatic even in adults. About 60% of adult patients receiving stimulant medication showed moderate-to-marked improvement, as compared with 10% of those receiving placebo. The core symptoms of hyperactivity,... 

Another theory for the action of stimulant diugs in ADHD involves effects on nonstiiatal monoamine systems. Frontal cortical dopamine, norepinephrine, and serotonin are clearly important in cognitive functioning and impulse control. These neurotransmitters directly modulate reward-related behaviors associated with the striatal dopamine system. Moreover, the amygdala may be pharmacologically influenced leading to enhanced... 

Psychostimulants. Figure 3 Effect of methylphenidate depending on baseline tonic (T) and phasic (P) dopamine levels. In a normal state only minimal changes are noted (which points to a rather low abuse potential). From a hypoactive state, methylphenidate increases both Tand P levels. However, this is much more true for the strongly lowered P tone. In contrast, in moderately hyperactive states and ADHD, T levels are increased and P levels are decreased, respectively, correlating with the baseline levels (adapted from [2]). 

Taylor JR, Jentsch JD (2001) Stimulant effects on striatal and cortical dopamine systems involved in reward-related behavior and impulsivity. In Solanto MV, Arnsten AFT, Castellanos FX (eds) Stimulant drugs and ADHD, Oxford University Press, pp 104-133... 

Acyl-CoA Synthetase Adaptive Immunity Adaptor Proteins Addiction Addison s Disease Additive Interaction Adenosine Adenosine Receptors Adenoviruses Adenylate Cyclase Adenylyl Cyclases ADH ADHD... 

Pemoline pem -oh-leen Cylert ADHD Insomnia, nervousness, headache, tachycardia, anorexia, dizziness, excitement 37.5-112.5 mg/d PO... 

The rates of comorbid psychiatric disorders such as depression, ADHD, and antisocial personality disorder are significantly higher in stimulant abusers... 

Alcohol Health Res World 22 122-123, 1998 Solhkhah R, Finkel J, Hird S Possible risperidone-induced visual hallucinations. J Am Acad Child Adolesc Psychiatry 39 1074-1073, 2000 Solhkhah R, Wilens TE, Prince JB, et al Bupropion sustained release for substance abuse, ADHD, and mood disorders in adolescents (NR31), in New Research Absrracts, Annual Meeting of the American Psychiatric Associarion. Washington, DC, American Psychiatric Associarion, 2001... 

ADHD Passive avoidance in spontaneously hypertensive rats Improves cognitive performance [57]... 

What other information do you need to assess for ADHD ... 

Although ADHD generally is considered a childhood disorder, symptoms can persist into adolescence and adulthood. The prevalence of adulthood ADHD is estimated to be 4%, with 60% of adults having manifested symptoms of ADHD from childhood.8,9 Further, problems associated with ADHD (e.g., social, marital, academic, career, anxiety, depression, smoking, and substance-abuse problems) increase with the transition of patients into adulthood. 

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