Disability in atypical parkinsonian syndromes is more dependent on memory dysfunction than motor symptoms

Background There is a gap in the systematic description and investigation of functional disability in corticobasal syndrome (CBS) and progressive supranuclear palsy (PSP). Additionally, the relations between disability, apraxia, cognitive and behavioural changes are not well understood in atypical parkinsonian syndromes. Methods Fifty patients were included in this study (CBS = 18; PSP = 11), including a subgroup of primary progressive aphasia-nonfluent variant (PPA-nfv = 21) who were used as a control group given the clinic-pathological overlap. Functional disability (basic and instrumental activities of daily living), general cognition and behavioural changes were evaluated at baseline, with a subgroup of patients being reassessed after 16 months. Results The corticobasal syndrome group had the most marked disability in basic activities in comparison to progressive supranuclear palsy and primary progressive aphasia-nonfluent variant. Longitudinal decline was marked for all three groups. In a linear regression examining factors behind functional disability in CBS and PSP, memory dysfunction emerged as the main factor (48.5%), followed by apraxia (14.9%) and atypical parkinsonian symptoms (9.6%). Conclusions Memory dysfunction is the most important factor in functional disability in CBS and PSP, which has to be taken into consideration in disease management, prognosis and planning of services to fully address patients' and families' needs.