Although hallucinations are considered to be a dopaminergic related phenomenon, the correlation between hallucinations with other features in Parkinson's disease (PD) still remains controversial.
To define the phenomenology and factors that contribute to hallucinations in patients with idiopathic PD, and to determine their correlation with the Parkinsonian motor state (on versus off).
A consecutive series of patients with PD were examined using the motor subscale of the Unified Parkinson's Disease Rating Scale (UPDRSm), Hoehn and Yahr stage (HY), Mini-Mental State Examination (MMSE) and a questionnaire on hallucinations, motor state and sleep disorders. Patient's characteristics, treatment, motor status, and sleep disorders were correlated with the presence of hallucinations using parametric and non-parametric tests.
Thirty eight patients (18 men, 20 women) with a mean age of 73.3 +/- 7 years, PD duration of 9 +/- 7 years, median HY stage of 2 (2-5), and a MMSE of 25 +/- 4 were included. Compared to non hallucinators (15 patients), hallucinators (23 patients) had a higher HY (p = 0.01), UPDRSm (p = 0.004), PD duration (p = 0.01), PD treatment duration (p = 0.03), presence of sleep disorders (p = 0.05) and were taking higher total daily doses of levodopa (p = 0.05). A multivariate analysis found that higher UPDRSm scores and total levodopa daily dose were the main clinical variables associated with hallucinations. Age, gender, MMSE scores, prior levodopa dose or dopaminergic agonists, and motor state did not influence the presence of hallucinations.
In this study, hallucinations were not correlated with the Parkinsonian motor state. Although motor severity impairment and total levodopa daily dose were the main clinical variables associated with hallucinations, other clinical factors such as sleep disorders and treatment duration should be considered.