Rivastigmine augmentation in the management of chronic schizophrenia with comorbid dementia: an open-label study investigating effects on cognition, behaviour and activities of daily living

Abstract

Comorbid schizophrenia and dementia is becoming an increasingly common phenomenon. Because rivastigmine, a reversible acetylcholinesterase inhibitor, appears to delay the progression of Alzheimer's disease, it may also improve or delay the cognitive and behavioural disturbances evident in elderly chronic schizophrenia patients with comorbid cognitive decline. The aim of this study was to investigate augmentative rivastigmine administration in this population and to determine any effect on cognition, behaviour and ‘activity of daily living’ (ADLs) capabilities. Thirteen subjects with comorbid schizophrenia and dementia were administered open-label oral rivastigmine (9 mg/day) for a period of 12 weeks. The results indicated improvement in Mini-Mental State Examination scores (P<0.01), Alzheimer's Disease Assessment Scale-cognitive subscale scores (P<0.001), ADL scores (P<0.01) and Positive and Negative Syndrome Scale scores (P<0.01). Study observations indicate beneficial effects of rivastigmine administration in this subpopulation of schizophrenia patients. Following on from other studies of cholinesterase inhibitor agents, clinical improvement in this patient subpopulation may extend to the class of cholinesterase inhibitor agents in general and not necessarily be a specific effect of any of the medications. The effects noted may be specific to the subpopulation of comorbid schizophrenia and dementia rather than schizophrenia in general. Although speculative, these effects may be related to cholinergic dysfunction, which has been hypothesized to be present in some patients with schizophrenia.