Elevated Incidence of Antipsychotic Use Found Prior to Parkinson Disease Diagnosis

Initiation of antipsychotics was shown to be significantly higher among patients with Parkinson disease (PD) before and after diagnosis, according to study findings published in Parkinsonism & Related Disorders.

Nearly half of people with PD report psychotic symptoms, including hallucinations, delusions, and false sense of presence, noted researchers, with use of antipsychotics common among these patients. Notably, these symptoms may occur prior to the initiation of motor fluctuations during the prodromal stage, but the underlying cause of this, as well as PD-related psychosis, remains poorly understood.

“There is, as far as we know, no previous studies about the incidence of antipsychotic use before PD diagnosis. This information has clinical relevance in relation to understanding the burden of psychotic symptoms already in the prodromal stage,” said the study authors.

Leveraging data from the nationwide register-based FINPARK-study, which included 20,994 ​​community-dwelling patients with PD at the time of diagnosis who received special reimbursement for PD drugs between 1996 and 2015 in Finland, they sought to compare the incidence of antipsychotic use among people with and without PD from 10 years before to 10 years after the diagnosis.

“For those diagnosed before or during the year 2005, we used year 1995 as a 1-year washout period. We excluded persons who had bought antipsychotics during the washout period or those who were hospitalized for over 50% of the washout period or hospitalized for the last 90 days of the washout period,” explained researchers.

A total of 20,994 people with PD and 142,944 people without were included in the analysis, with the study cohort evaluated on the rate of antipsychotic initiations (initiation rate [IR]) per 1000 person-years for every 6 months beginning from 10 years before to 10 years after the diagnosis or index date (date of PD diagnosis).

Overall, 26.9% (n = 5654) of people with PD initiated antipsychotics vs 9.7% (n = 13,887) of people without PD during the entire follow-up (IR, 20.3 and 6.3 per 1000 person-years for persons with and without PD, respectively; IR ratio [IRR], 3.20; 95% CI, 3.10-3.30).

The initiation rates were shown to be higher in patients with PD before (IR, 6.5 and 3.0 per 1000 person-years; IRR, 2.18; 95% CI, 2.03-2.33) and after the index date (IR, 43.3 and 11.7 per 1000 person-years; IRR, 3.70; 95% CI, 3.57–3.83). Moreover, the incidence rate was found to increase in people with PD approximately 4 years prior to PD diagnosis.

Most commonly initiated antipsychotics were quetiapine (n = 3642; 64.4%) in people with PD and risperidone (n = 5232; 37.7%) in controls.

The researchers concluded that psychotic symptoms may be challenging to recognize as prodromal symptoms of PD since they can occur years before motor symptoms and “thus, cannot be clinically associated with the diagnosis of PD.”

Reference

Lilja S, Tolppanen AM, Koponen M, Hartikainen S, Tiihonen M. Incidence of antipsychotic use among community dwellers with and without Parkinson’s disease. Parkinsonism Relat Disord. 2022 Aug 24;103:69-72. doi:10.1016/j.parkreldis.2022.08.024