Affiliations: The Michael Trimble Neuropsychiatry Research Group,
Department of Neuropsychiatry, BSMHFT and University of Birmingham, Birmingham,
UK | Department of Neurology, UHBFT and University of
Birmingham, Birmingham, UK
Note: [] Correspondence: Hajar Alobaidi, Department of Neuropsychiatry,
The Barberry National Centre for Mental Health, Birmingham B15 2FG, UK. Tel.:
+44 121 3012317; Fax: +44 121 3012291; E-mail: HXA840@bham.ac.uk
Abstract: Objectives: The pharmacotherapy of Parkinson's disease (PD) is often
challenging as clinicians have to find a favourable balance between the
efficacy on motor symptoms and side effect profiles of different dopaminergic
medications. We aimed to assess the available evidence on the role of dopamine
agonist monotherapy as an alternative to Levodopa in the treatment of motor
symptoms of PD, along with the role of dopamine antagonists in the treatment of
PD-related psychosis. Methods: We performed a systematic literature review using the
databases MEDLINE, EMBASE, PsycINFO and the Cochrane Library Central register
of controlled trials. Two searches were performed, 'Search 1' extracting trials
on dopamine agonists, and 'Search 2' on atypical antipsychotics. Eligible
studies were Double-blind Randomised Controlled Trials (RCTs) using the Unified
Parkinson's Disease Rating Scale (UPDRS) and the Brief Psychiatric Rating Scale
(BPRS) as outcome measures for Search 1 and 2, respectively. Results: 16 relevant RCTs were extracted from the search results.
Overall, dopamine agonists were shown to significantly improve UPDRS scores,
with a mean percentage improvement of 14.4% compared to −1.9% in the
control arm (P value < 0.05). However, their side effect profile illustrated
they were associated with twice the incidence of psychotic symptoms in
comparison to the controls. The results on the efficacy of atypical
antipsychotics for the treatment of PD-related psychosis were not
significant. Conclusions: This evidence-based review confirmed that dopamine
agonists can be an effective and safe treatment as monotherapy in PD, however
psychotic symptoms remain a significant side effect. Atypical antipsychotics
may not be relied upon for the correction of these symptoms due to inconsistent
results about their efficacy.
Keywords: Antipsychotic, dopamine agonist, monotherapy, motor symptoms, Parkinson's disease, psychosis
