VISUAL HALLUCINATIONS IN PARKINSON’ S DISEASE WERE ASSOCIATED WITH DECREASING BLOOD FLOW IN THE BILATERAL POSTERIOR CINGULATE CORTEX ON 123I-IMP-SPECT

Abstract Background Psychosis is known as one of the non-motor symptoms of Parkinson’ s disease (PD). Psychosis is typically associated with an increased burden regarding living activities in PD and thus constitutes a serious public health problem. Aims & Objectives We hypothesized that the visual hallucinations associated with PD would be predicted by neurodegeneration of specific regions. We consecutively enrolled 228 patients with PD between October 2016 and March 2021 at Juntendo University Hospital in Japan. Method All patients were assessed for motor function, cognition, mental state, and REM sleep-related events using the REM sleep behavior disorder (RBD) Single-Question Screen (RBD1Q), and for regional cerebral blood flow (rCBF) using N-isopropyl-p-123I-iodoamphetamine single photon emission tomography. Results The patients were divided into two groups: one with a history of visual hallucinations (Hal-PD; n = 119) and one without (nHal-PD; n = 109). Three factors were associated with Hal-PD: sex and scores on both the RBD1Q and Odor Stick Identification Test for Japanese (OSIT-J). In single photon emission tomography data, rCBF in the bilateral posterior cingulate (PC) and right cuneus were significantly lower in the Hal-PD than in the nHal-PD group. RBD1Q scores were associated with rCBF in the bilateral PC. Discussion & Conclusions Visual hallucinations were associated with rCBF in the bilateral PC and OSIT-J scores. Especially, rCBF in the left PC was an independent risk factor. RBD1Q scores were significantly associated with Hal-PD. RBD1Q scores may be an easy surrogate factor for visual hallucinations in settings where rCBF cannot be measured.