Objective: To assess the utility of the Philadelphia Apathy Computerized Task (PACT) in measuring goal-directed behavior in Parkinson’s disease (PD).

Background: Impairment in goal-directed behavior contributes to apathy, a common and disabling non-motor symptom in PD. Preliminary work using the PACT shows that PD patients have selective impairments in each component of goal-directed behavior: motivation, planning and initiation (Fitts, 2016). However, the functional impact of these impairments is unknown.

Methods: Non-demented PD subjects were administered the PACT, a computerized reaction time test of motivation (reward and penalty conditions), planning and initiation in both the ‘on’ and ‘off’ medication states, and a neuropsychological battery which included the Montreal Cognitive Assessment and Geriatric Depression Scale. Care partners completed the Neuropsychiatric Inventory (NPI) and Zarit Burden Interview. We assessed the correlation between each PACT subtask and clinical outcomes.

Results: 27 PD subjects (14 men, 13 women, mean age 70 (sd 6.5)) participated. There was no difference in PACT subtask performance when completed in the ‘on’ and ‘off’ states (mean initiation: ‘on’ score 410 ms, ‘off’ score 385 ms, p=0.10; mean planning: ‘on’ score 1472 ms, ‘off’ score 1490 ms, p = 0.71; mean reward ‘on’ score 765 ms, ‘off’ score 708 ms, p=0.21; mean penalty ‘on’ score 748 ms, ‘off’ score 722 ms, p=0.13). Performance on each PACT subtask was correlated with caregiver burden (initiation Spearman’s rho 0.51, p<0.01; planning 0.69, p<0.01; reward 0.63, p<0.01 and penalty 0.73, p<0.01). After adjusting for age, sex, motor speed, cognitive abilities, depressive symptoms, and level of dopaminergic treatment, worse performance on the initiation (β=0.08, 95% CI 0.01, 0.14), planning (β=0.02, 95% CI 0.01, 0.03), reward (β=0.02, 95% CI 0.01,0.04) and penalty (β=0.04, 95% CI 0.01, 0.07) subtasks were still associated with greater caregiver burden. However, there was no correlation between NPI apathy scores and caregiver burden (Spearman’s rho 0.26, p=0.20).

Conclusions: The PACT provides a multi-dimensional objective measure of goal-directed behavior in PD that will be helpful in understanding mechanisms underlying apathy and their clinical outcomes, and may be a more sensitive tool than traditional caregiver reports of apathetic behavior.

References: Fitts W, Massimo L, Lim N, Grossman M, Dahodwala N. Computerized assessment of goal-directed behavior in Parkinson’s disease. Journal of Clinical and Experimental Neuropsychology 2016 Nov; 38(9): 1015-25.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/impaired-performance-on-measures-of-goal-directed-behavior-are-associated-with-greater-caregiver-burden-in-parkinsons-disease/