Background: Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder leading to progressive motor, cognitive and functional decline. Antidopaminergic medications (ADMs) are frequently used to treat chorea and behavioural disturbances in HD.
Objective: We aimed to assess how the use of such medications was associated with the severity and progression of the motor aspects of the condition, given that there have been concerns that such drugs may actually promote neurological deterioration.
Methods: Using multiple linear regression, supplemented by principal component analysis to explore the overall correlation patterns and help identify relevant covariates, we assessed severity and progression of motor symptoms and functional decline in 651 manifest patients from the REGISTRY cohort followed for two years. ADM treated versus non-treated subjects were compared with respect to motor impairment at baseline and progression rate by means of multiple regression, adjusting for CAG-repeat and age.
Results: Patients treated with ADMs had significantly worse motor scores with greater functional disability at their first visit. They also showed a higher annual rate of progression of motor signs and disability over the next two years. In particular the rate of progression for oculomotor symptoms and bradykinesia was markedly increased whereas the rate of progression of chorea and dystonia was similar for ADM and drug naïve patients. These differences in clinical severity and progression could not be explained by differences in disease burden, duration of disease or other possible prognostic factors.
Conclusions: The results from this analysis suggest ADM treatment is associated with more advanced and rapidly progressing HD although whether these drugs are causative in driving this progression requires further, prospective studies.
Keywords: Huntington disease; antipsychotics; dopamine; observational study; tetrabenazine.