Changes in motor activity level in individuals with frontotemporal dementia

Changes in motor activity are common in individuals with Frontotemporal dementia (FTD). Yet, it remains unclear why some individuals become motorically hyperactive, while others hypoactive even in early stages of the disease. This study aimed to examine the relationship between motor activity level and (1) FTD clinical subtype, and (2) cortical thickness and subcortical volumes. Eighty-two charts were retrospectively reviewed from patients meeting consensus criteria for one of the three main clinical subtypes of FTD: probable bvFTD, semantic variant Primary Progressive Aphasia (PPA), or non-fluent variant PPA. Participants were assigned to one of three groups: (1) hyperactive, (2) hypoactive, or (3) no record of change. Hyperactivity was prevalent among bvFTD (58.5%) and semantic PPA (68.8%) subtypes while hypoactivity was less common in both subtypes (29.3% and 18.8%, respectively). The majority of patients with non-fluent PPA showed no record of change in motor activity (66.7%). The analysis of cortical thickness and subcortical volumes did not identify significant associations with motor activity levels. In conclusion, increased motor activity is highly prevalent among individuals with FTD, especially bvFTD and svPPA subtypes. These findings may inform prognosis and prediction of changes in motor activity, and allow planning for appropriate environmental and behavioural interventions. Future studies with prospective, standardized longitudinal collection of information regarding the type and level of change in motor activity, including wearable measures of actigraphy, may help to further delineate the onset and progression of abnormal motor behaviours and determine neuroanatomic associations in FTD.