Longitudinal behavioral and neuropsychiatric changes and their MRI correlates in predementia <i>C9orf72</i> and <i>GRN</i> mutation carriers

BackgroundNeuropsychiatric symptoms (NPS) progress differently among individuals with autosomal dominant familial frontotemporal dementia (FTD) caused by genetic mutations in granulin (<i>GRN</i>+) or chromosome 9 open reading frame 72 (<i>C9orf72</i>+).ObjectiveTo determine whether these differences begin prior to the onset of dementia, we compared the longitudinal rates of change of NPS among <i>C9orf72</i>+, <i>GRN</i>+, and noncarrier controls in the predementia phase. Additionally, we assessed whether the NPS changes were correlated with gray matter (GM) volume loss or white matter signal abnormalities (WMSAs) on magnetic resonance imaging (MRI).MethodsEighty-two participants (N = 10 <i>GRN</i>+, N = 23 <i>C9orf72</i>+, N = 49 noncarriers) were followed using various NPS rating scales for an average of 7.8 years. Group differences were compared using generalized linear mixed-effects models. GM volume and WMSA volumes were measured on 42 participants (N = 8 <i>GRN</i>+, N = 11 <i>C9orf72</i>+, N = 23 noncarriers) who had two MRI visits. These measures were correlated with the rates of NPS score changes.Results<i>C9orf72</i>+ showed higher rates of increase in the Beck Depression Inventory (BDI) total and the Iowa Scales of Personality Change (ISPC) dysexecutive disturbance scores versus noncarriers. <i>GRN</i>+ showed higher rates of increase in the BDI total, the ISPC total, and the emotional/social disturbance scores versus noncarriers; and higher rates of increase in the ISPC emotional/social personality and distressed disturbance scores versus <i>C9orf72</i>+. Across all groups, faster WMSA accumulation correlated with higher rates of increase in the Neuropsychiatric Inventory Questionnaire total score.ConclusionsChanges in NPS differ among <i>C9orf72</i>+, <i>GRN</i>+, and noncarrier controls prior to the onset of overt FTD.