Characterization of Apathy in Frontotemporal Dementia
Apathy has been defined as a deficit in drive and motivation, yet has been historically difficult to operationalize. Apathy occurs commonly in dementia and is associated with negative outcomes for both the patient and the caregiver. This study characterizes daytime activity and apathy in patients with behavioral variant (bvFTD) and semantic dementia (SD) and their family caregivers. Twenty-two patient-caregiver dyads were enrolled: 13 FTD, 9 SD and data on dementia severity, cognition, behaviors, activity, daytime sleepiness were collected. Patients and caregivers wore Actiwatches continuously for 2 weeks to record activity. Variables were examined between groups. Apathy was present in 100% of the patients with FTD and in 89% of patients with SD. Patients with FTD spent 25% of their day immobile while patients with SD spent 16% of their day inactive. FTD caregivers spent 11% of their day immobile and SD caregivers 9%. Apathy correlated with high levels of emotional distress for the caregivers in FTD, but not SD. Averages of hourly activity counts revealed the lowest amount of daytime activity was among patients with FTD followed by their caregivers, with the highest activity among SD caregivers. These results were present in patients in relatively mild disease stages. There was little evidence that factors other than apathy, for example, depression, physical impediments, or sleepiness, were contributing to the lower activity. FTD is associated with greater daytime activity disturbance (lower activity and greater numbers and duration of immobility bouts) compared to SD and the clinical manifestations of FTD produce different and more distressing impacts on the caregiver. Results from this study provide objective data contributing to an operational definition of apathy.