Impact of apathy over the course of disease in amyotrophic lateral sclerosis.

Objective: Apathy is a common syndrome in amyotrophic lateral sclerosis (ALS), particularly Initiation apathy (lack of motivation for self-generated thoughts and/or actions). The aim was to determine how apathy subtypes change over time, and their impact on individuals' quality of life (QoL), caregiver-wellbeing and burden or strain. Methods: Forty-nine people living with ALS (pwALS) and their caregiver participated in interviews at three time-points (3-month intervals). They completed the Dimensional Apathy Scale (DAS), and assessments of depression, anxiety and emotional lability, cognitive-behavioral functioning and functional disability. PwALS QoL, caregiver burden or strain, caregiver-wellbeing and care-related QoL were measured. Results: At baseline, Initiation apathy was most common (38.8%, N = 19) followed by Emotional apathy (16.3%, N = 8). Lower caregiver-wellbeing was observed in Initiation apathy (p < 0.05) and Mixed-emotional apathy (p < 0.001) groups, where only Initiation apathy had higher caregiver burden or strain (p < 0.05) than those with no apathy. Over three visits (N = 31), there was an increase in Initiation apathy (p < 0.01) and Executive apathy (p < 0.05) over time. While controlling for functional disability, only increasing Emotional apathy was associated with increasing caregiver burden or strain (p < 0.05), decreasing caregiver-wellbeing (p < 0.001), and decreasing care-related QoL (p < 0.05). Conclusion: Initiation and Emotional apathy were variably associated with higher levels of caregiver burden or strain and decreased caregiver-wellbeing in ALS. As ALS progresses, Initiation and Executive apathy increased, while Emotional apathy has been shown to impact care-related QoL, caregiver-wellbeing and burden or strain. This has implications for understanding the progression of apathy subtypes and the interplay of caregiver-wellbeing, QoL, burden, or strain.