We studied the prevalence of psychotropic use and psychotropic polypharmacy in persons with Parkinson's disease (PD) during a 10-year follow-up, because longitudinal studies on this topic are scarce although non-motor symptoms of PD are often treated with psychotropics.

The prevalence of any psychotropic, benzodiazepines and related drugs (BZDRs), antidepressants, antipsychotics in six-month time windows from five years before to five years after PD diagnosis was studied in a Finnish nationwide register-based study of 17 379 people with clinically verified PD diagnosis during 2000–2014 and compared to a matched comparison cohort without PD (n = 115 386).

During the follow-up, psychotropic use increased from 18% to 35% in persons with PD and from 14% to 20% in the comparison cohort. Psychotropic polypharmacy and use of all psychotropic subgroups were more frequent in the PD than in the non-PD cohort throughout the follow-up. In comparison, cohort BZDRs were the most frequently used psychotropics during the whole follow-up. In the PD cohort, BZDRs were the most frequently used psychotropic group until three years after PD diagnosis, with the highest prevalence just before the index date (19.4%). After that, antidepressants were the most commonly used psychotropics. In the PD cohort, the psychotropic polypharmacy increased from 5% to 10% during the follow-up. The differences were not explained by dementia.

The results likely reflect the onset of non-motor symptoms already before diagnosis and increasing symptomatology with disease progression. Alternatively, they may reflect increased healthcare contact. Still, the findings are concerning as all psychotropics increase the risk of adverse effects including falls and fall-related fractures.