October 2011
Factor
SA, Steenland NK, Higgins DS, Molho ES, Kay DM, Montimurro J, Rosen AR, Zabetian
CP, Payami H
Our aim was to examine disease-related and genetic correlates of the
development of psychotic symptoms in a large population of patients with
Parkinson's disease.
We studied 500 patients with Parkinson's disease
from the NeuroGenetics Research Consortium using logistic regression
models. Predictors were demographic, clinical (motor/nonmotor features),
and genetic, measured as continuous or dichotomous variables.
Continuous measures were divided into population-based tertiles.
Results
are given as odds ratios (95% confidence intervals) for dichotomous
variables and by ascending tertile for continuous variables. Psychotic
symptoms were associated with increasing age: 4.86 (1.62–14.30) and 6.25
(2.09–18.74) (test for trend: P = 0.01); and duration of disease: 3.81 (1.23–11.76) and 5.33 (1.68–16.89) (test for trend: P
= 0.03). For nonmotor features, we demonstrated positive trends with
depression: 1.31 (0.47–3.61) and 5.01 (2.04–12.33) (test for trend: P < 0.0001); cognitive dysfunction: 0.69 (0.26–1.84) and 2.51 (1.00–6.29) (test for trend: P = 0.03); and an excess for those with sleep disorders: 2.00 (1.03–3.89) (P
= 0.04). Psychotic symptoms were not associated with tremor or postural
instability scores, but there was an association with freezing of gait:
3.83 (1.67–8.75) (P < 0.002). Psychotic symptoms were not
associated with the presence of any examined polymorphisms in the
apolipoprotein, alpha-synuclein, or microtubule associated protein tau
genes.
This is the largest study to examine correlates of psychotic
symptoms in Parkinson's disease. We discovered a novel association with
freezing of gait. We demonstrated an association with depression and
duration of disease, both of which were inconsistently related in
previous studies, and confirmed the association with age, cognitive
dysfunction, and sleep disorders.
