Analysis of the cognitive enhancing effects of modafinil in schizophrenia

Summary

Key words: schizophrenia; modafinil; Provigil; smart drugs; cognitive enhancement; high functioning.

Introduction and Overview

Numerous neuropsychiatric disorders, such as attention deficit hyperactivity disorder (ADHD), schizophrenia, frontotemporal dementia and Parkinson's disease, are characterized by cognitive impairments. The potential public health benefit of improving current treatments for cognitive disabilities is undisputed (Meltzer, 2003). The disorder of schizophrenia illustrates particularly well the need for specific treatments of cognitive dysfunction. The clinical targets for schizophrenia have traditionally been the delusions and hallucinations that characterize the disorder, and for which neuroleptic agents are most efficacious (Campbell et al., 1999). However, although these symptoms define the core diagnostic criteria of this illness, it is now recognized that the cognitive and motivational impairments in schizophrenia are closely related to the profound long-term disability typically produced by the disease (Hyman & Fenton, 2003). Indeed, cognitive deficits are the major cause of poor psychosocial function and impoverished quality of life in patients with schizophrenia for whom psychosis is controlled by currently available therapies (Geyer & Tamminga, 2004).

Neuropsychological studies of patients with schizophrenia have consistently identified deficits on tests of executive function, known to be sensitive to frontal lobe damage. Deficits in cognitive flexibility, working memory and planning have been widely reported, together with more recent evidence of impairments in inhibitory control (Badcock et al., 2002; Pantelis et al., 1999; Elliott et al., 1995; Pantelis & Brewer, 1995). Moreover, cognitive flexibility, as measured by the Wisconsin Card Sorting Test (WCST), has been related to community outcome in these patients (Hartman et al., 2003; Koren et al., 1998; Green, 1996) and to response to psychological intervention (Wykes et al., 2003).