Amelioration of specific working memory deficits by methylphenidate in a case of adult attention deficit/hyperactivity disorder.

Cognitive neuroscience has provided an extensive literature on the neuroanatomy and psychopharmacology of working memory. However, while it has been shown that children with attention deficit/hyperactivity disorder (AD/HD) have deficits in working memory, relatively little is known about working memory functions in adults diagnosed with AD/HD. Furthermore, it remains to be seen whether methylphenidate (Ritalin), which is used in the treatment of childhood AD/HD can improve performance deficits in adult AD/HD patients. We have used three paradigms of spatial working memory validated in cortical lesion patients, and psychopharmacological and neuroimaging studies, in order to examine the effects of methylphenidate administration in a case of an adult diagnosed with AD/HD. In the AD/HD patient at baseline testing, performance on a test of spatial recognition memory and on a task of self-ordered spatial working memory was shown to be impaired. Importantly, the impairments on the self-ordered spatial working memory task were ameliorated by an acute oral dose of methylphenidate (0.5 mg/kg). These findings provide insights into the possible neurochemical and neuroanatomical substrates of the action of methylphenidate in AD/HD and suggest a useful methodology for further research into this potentially debilitating disorder.