De novo psychosis in a new onset Parkinson disease

To the Editor

Psychotic symptoms are common in Parkinson disease (PD) with prevalence rates reported between 20% and 60% (Forsaa et al., 2010). Predictive factors for PD-associated psychosis (PDP) are: advanced age and illness stage, presence of dementia, use of anti-Parkinsonian medication and co-morbid depression (Starkstein et al., 2012). To date, there is only a small evidence base for psychosis associated with PD in its early stages. The PRIAMO study (Morgante et al., 2012) recently reported a baseline prevalence of 3% for PDP in 495 patients with early stage PD.

We report a case in which psychotic symptoms and Parkinsonian symptoms occurred almost concurrently, without any medication administration.

Mr A is a 53-year-old Caucasian man with no prior personal or family history of mental illness or PD. He had worked as a clerk officer for almost 30 years. In May 2012, he was seen by his GP for a 2-year history of worsening persecutory ideations that he was under surveillance at work and home. His wife also reported a 2-year history of tremor, initially involving his right leg, which then evolved to involve his right hand. He was commenced on citalopram and olanzapine by his GP. Unfortunately, olanzapine worsened his tremor with little effect on the psychosis. In July, he was admitted to hospital under neurology with a diagnosis of ‘atypical Parkinsonism’ and was noted to have masked facies and tremor in his right limbs without any resting tremor. Cogwheel rigidity and bradykinesia were evident as well as a narrow-based gait with reduced right arm swing. His Mini Mental State Examination (MMSE) was 30/30, Montreal Cognitive Assessment (MoCA) was 25/30 and Frontal Assessment Battery (FAB) was 17/18. Electroencephalography and magnetic resonance imaging were both unremarkable. He was discharged on levodopa/benserazide 50 mg/12.5 mg, quetiapine 25 mg. While there was a slight improvement of his delusion initially, he reported worsening of tremor and gait on quetiapine. Subsequently, he was commenced on low-dose clozapine, which was slowly titrated up to 87.5 mg. Although Mr A resigned from work and continues to report mild persisting persecutory ideation, his Parkinsonian symptoms have stabilized since the commencement of clozapine.

Our case illustrates a de novo psychosis in an individual with few predictive factors for PDP. This case contributes to the accruing evidence that even those at an early stage of PD can develop psychotic symptoms. In particular, Mr A had few predictive/risk factors for PDP, suggesting an intimate neurochemical relationship between psychosis and PD independent of iatrogenic factors.