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
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.