Psychosis associated to Parkinson's disease in the early stages: relevance of cognitive decline and depression

ABSTRACT
Objective To evaluate the prevalence of psychosis
associated with Parkinson’s disease (PSY-PD) in its early
stages, its incidence over a 24 month follow-up period and
the association with motor and non-motor clinical features.
Methods PRIAMO is a 2 year longitudinal observational
study that has enrolled patients with parkinsonism in 55
Italian centres. A cohort of 495 patients with early
disease stage PD (baseline Hoehn and Yahr score #2,
disease’s duration (median) 3.4 years) were followed for
2 years. PSY-PD was evaluated by means of a clinician
rated questionnaire and defined as the presence of at
least one of the following symptoms occurring for at
least 1 month: illusions, hallucinations, jealousy ideas
and persecutory ideas. Patients with and without PSY-PD
were compared on several clinical variables,
encompassing motor and non-motor features.
Results The prevalence of PSY-PD at baseline was 3%;
the incidences at 12 and 24 months were 5.2% and 7.7%,
respectively. Longer disease duration and prescription of
dopamine agonists at baseline were associated with the
development of PSY-PD over the 24 month period. At this
follow-up time, worse disease severity, decline in cognitive
performances, presence of depressive symptoms and
anxiety were more frequently observed in PSY-PD.
Conclusions Psychotic type symptoms may occur in the
early stages of PD although less frequently than in later
stages. Beyond dopaminergic treatment, there are
disease related factors, such as disease severity and the
occurrence of cognitive and depressive symptoms,
which may underlie the onset of psychotic type
symptoms from the earliest stages