Relationship between visual hallucinations and REM sleep behavior disorder in patients with Parkinson's disease

REM sleep behavior disorder (RBD) has been documented to precede or to co-occur with Parkinson's disease (PD). Parkinson's disease is one of the most common neurological conditions associated with visual hallucinations. Cognitive dysfunction is present in PD, even at the early stages of these diseases. In this study we aimed to investigate the relationship between visual hallucinations and RBD in patients with idiopathic Parkinson's disease (IPD). Additionally, we evaluated the association of the cognition and the pattern of cognitive impairment with VHs and RBD, effects of factors like duration and severity of the disease and duration of levodopa usage.

Seventy-nine patients, diagnosed as PD, were included the study and then, patients were divided into four groups; with RBD and VHs (group 1), with RBD but no VHs (group 2), with VHs but no RBD (group 3), without RBD and VHs (group 4). We compared each group with the others according to demographic characteristics and neuropsychological test scores.

Of all patients, in 46% (n=36) RBD and in 48% (n=38) VHs were observed. Our study established VHs in 58% of patients with RBD, and RBD in 55% of patients with VHs. However, due to a 40% incidence of VHs in patients without RBD, RBD and VHs were not found to be correlated. All of the neuropsychometric test scores did not reveal significant difference between groups.

Although it seems like there is a small association between RBD and VHs in our patients, it was not significant. Group 1 presented with significantly worse scores in UPDRS total scores and I, II subscores.