Executive functions are impaired in patients with Parkinson’s disease with visual hallucinations

Objectives:Although cognitive impairment has been identified as a risk factor for visual hallucinations (VHs), more specific neuropsychological deficits underlying such phenomena have not been established. Here, we investigate the link between executive dysfunction and the occurrence of VHs.Methods:We evaluated three groups—17 patients with Parkinson’s disease (PD) with VHs, 20 patients with PD without VHs and 20 age-matched controls—on a battery of tests previously reported to evaluate executive functions, namely tests of inhibitory ability, short-term memory and working memory.Results:Differences were found on tests of inhibitory ability, for which the patient group with VHs showed impairment when compared with the non-hallucinating group.Conclusions:Patients with PD with VHs have substantially greater impairment of inhibitory ability than patients without VHs. These findings support interactive models of the genesis of visual hallucinations in PD.