Predictable Risk Factors for the Feeling of Presence in Patients with Parkinson's Disease

The detailed relations between feeling of presence (FOP) and hallucinations remain uncertain in Parkinson's disease (PD). The prospective studies of risk factors predicting the onset of FOP have yet to be reported on. We prospectively investigated risk factors for FOP to identify factors related to the development of first-onset hallucinations from FOP in patients with PD who were followed up for 2 years.

From among the 100 consecutive patients, we registered 78 patients with PD. Once every 1 to 3 months, the same sole interviewer personally asked these patients during 2 years of follow-up. Seventeen independent variables were evaluated using multivariate logistic regression analysis using forced entry.

Seventeen patients newly presented with FOP. In 7 patients, hallucinations developed after the onset of FOP. Twenty-six patients newly presented with visual hallucinations. On multivariate logistic regression analysis, the score for UPDRS part 4 (odds ratio [OR] = 1.413; P = 0.049; 95% confidence interval [CI] = 1.002-1.991) and an increase in dose of antiparkinsonian medications (OR = 0.132; P = 0.033; 95% CI = 0.021-0.846) were related to onset of FOP. Zung depression score (P = 0.017) differed significantly between patients who had FOP without hallucinations and those who had FOP with hallucinations (39.2 ± 5.21 and 46.25 ± 2.86, respectively).

Motor complications and increasing doses of antiparkinsonian medications may predict onset of FOP, and depression might be helpful for predicting the future development of hallucinations from FOP.