Action fluency identifies different sex, age, global cognition, executive function and brain activation profile in non-demented patients with Parkinson's disease.

Patients with Parkinson's disease (PD) have difficulties processing action words, which could be related to early cognitive decline. The action fluency test can be used to quickly and easily assess the processing of action words in PD. The goal of this study was to characterize how the action fluency test relates to personal characteristics, disease factors, cognition, and neural activity in PD. Forty-eight participants with PD (34 male, 14 female) and 35 control participants (16 male, 19 female) completed functional neuroimaging using a set-shifting task and a neuropsychological assessment including the action fluency test. PD participants with a score one standard deviation below the norm or lower on the action fluency test were identified. All PD participants with poor performance (PD-P, n = 15) were male. They were compared to male PD participants with scores within the normal range (PD-N, n = 19) and male healthy controls (HC, n = 16). PD-P were older, had lower global cognition scores, lower executive functions scores, and decreased activity in fronto-temporal regions compared with PD-N. There was no difference between the two PD groups in terms of the duration of the disease, dose of dopaminergic medication, and severity of motor symptoms. PD-N were younger than HC, but there was no other significant difference between these groups. The action fluency test identified a subgroup of PD patients with distinct sex, age, global cognition, executive functions, and brain activity characteristics. Implications for the evaluation of cognition are discussed.