Impaired option generation underpins deficient reasoning in Parkinson's disease patients with apathy

Apathy is a debilitating neurological syndrome known to be associated with executive dysfunction, particularly affecting abstract reasoning. However, the underlying cognitive mechanism remains unclear. Recently, it has been proposed that one cognitive process disrupted in apathy is option generation. We investigated whether impaired option generation could explain deficient reasoning in apathy. Data was retrospectively analyzed from patients with Parkinson's disease (n = 51) who had completed the Lille Apathy Rating Scale and the Brixton Spatial Anticipation Task (Brixton), a measure of inductive reasoning. A hierarchical regression analysis showed that higher levels of apathy predicted poorer Brixton performance. Detailed analysis of Brixton errors was conducted to investigate the cognitive process underlying this relationship. Additional hierarchical regression analyses showed that apathy specifically predicted Brixton errors associated with a failure to generate either correct or incorrect rules. These findings suggest that deficient reasoning in apathy may be underpinned by impaired option generation.