Objective: To characterise the neuropsychiatric symptoms of patients with corticobasal degeneration (CBD).
Methods: The neuropsychiatric inventory (NPI), a tool with established validity and reliability, was administered to 15 patients with CBD (mean (SEM), age 67.9 (2) years); 34 patients with progressive supranuclear palsy (PSP) (66.6 (1.2) years); and 25 controls (70 (0.8) years), matched for age and education. Both patient groups had similar duration of symptoms and mini mental state examination scores. Semantic fluency and motor impairment were also assessed.
Results: Patients with CBD exhibited depression (73%), apathy (40%), irritability (20%), and agitation (20%) but less often had anxiety, disinhibition, delusions, or aberrant motor behaviour (for example, pacing). The depression and irritability of patients with CBD were more frequent and severe than those of patients with PSP. Conversely, patients with PSP exhibited significantly more apathy than patients with CBD. The presence of high depression and irritability and low apathy scale scores correctly differentiated the patients with CBD 88% of the time. The irritability of patients with CBD was significantly associated with disinhibition (r=0.85) and apathy (r=0.72). In CBD, apathy was associated with disinhibition (r=0.67); disinhibition was associated with aberrant motor behaviour (r=0.68) and apathy (r=0.67); and aberrant motor behaviour with delusions (r=1.0). On the other hand, depression was not associated with any other behaviour, suggesting that it has a different pathophysiological mechanism. Symptom duration was associated with total motor scores (r=0.69). However, total motor score was not associated with any behaviour or cognitive scores.
Conclusions: The findings indicate that frontosubcortical pathways mediating cognition, emotion, and motor function in CBD are not affected in parallel. Patients with CBD and PSP have overlapping neuropsychiatric manifestations, but they express distinctive symptom profiles. Evaluating the behavioural abnormalities of parkinsonian patients may help clarify the role of the basal ganglia in behaviour.