Memel, Molly B

AbstractBackgroundAccumulating evidence indicates that biological sex may influence clinical manifestation within the spectrum of frontotemporal lobar degeneration (FTLD), implying differences in cognitive reserve. Nonetheless, investigations into the impact of biological sex during the preclinical and minimally symptomatic stages of FTLD are lacking.MethodWe included 275 mutation carriers (158 females; 127 with C9orf72, 68 with GRN, and 80 with MAPT mutations) and 161 non‐carrier familial controls (97 females) from the ALLFTD Consortium (Staffaroni et al., Nat Medicine 2022). Participants underwent magnetic resonance imaging (MRI; 348 baseline, 338 longitudinal) and neuropsychological evaluations (394 baseline, 507 longitudinal). Behavioral symptoms were characterized with the Revised Self‐Monitoring Scale (RSMS) and the Neuropsychiatric Inventory (NPI severity scores). MRI‐derived regional volume estimates (RVE) were computed. Cognitive measures and RVE were normalized against sex‐matched controls. Cognitive composites (language, executive function, and visuospatial function) were calculated by averaging raw scores for each domain. Clinical characteristics and RVE comparisons were made between male and female participants. We adopted the residuals approach to explore behavioral and cognitive reserve by fitting a linear regression model for executive z‐scores as the response value and age, education, and RVE as explanatory variables.ResultIn mutation carriers, sex was not a significant differentiator in age, education level, disease severity, or mutation frequency. Most mutation carriers (188, 68%) were asymptomatic or mildly symptomatic at baseline. However, female mutation carriers exhibited significantly lower visuospatial performance at baseline (Cohen's d = ‐0.34, 95% CI[‐0.58, ‐0.09], p=.001). This difference remained significant among asymptomatic GRN mutation carriers (Cohen’s d = ‐0.73, 95% CI[‐1.22, ‐0.23], p=0.003) but not in other mutations. Following the residuals approach, female mutation carriers showed higher executive performance than males for the same amount of both frontotemporal and global atrophy as quantified by RVE (Cohen's d=0.45, 95 % CI[0.22, 0.67], p<.001). The observed higher executive reserve in women was particularly pronounced in C9orf72 carriers (Cohen's d=0.77, 95% CI[0.35, 1.20], p<.001) but not significant in GRN (p=0.48) and MAPT carriers (p=0.07). No differences in behavioral reserve reached statistical significance.ConclusionFemale sex might modulate early cognitive performance and confer higher executive reserve in FTLD mutation carriers.

AbstractBackgroundSex differences in neurodegenerative diseases can impact accurate diagnosis and management. Emerging data suggest there may be sex differences in frontotemporal dementia (FTD) prevalence and clinical manifestation. However, prior studies lacked longitudinal assessment and were limited in capturing sex differences in earliest stages of disease (e.g., preclinical). We evaluated how sex impacts longitudinal clinical outcomes in individuals carrying autosomal dominant variants for FTD.Method337 participants carrying pathogenic variants in MAPT, GRN, or C9orf72 completed longitudinal evaluations (2.4 average visits, range = 1‐6), including neuropsychological and functional assessments, and plasma analyzed for neurofilament light chain (NfL). FTLD Clinical Dementia Rating Scale (FTLD‐CDR) classified disease stage at study entry (FTLD‐CDR = 0: asymptomatic; FTLD‐CDR = 0.5: MCI; FTLD‐CDR> 0.5: Dementia). Linear mixed‐effects models evaluated the effect of sex on longitudinal clinical trajectories, including the effect of disease stage at study entry.ResultMale and female carriers were similarly distributed with respect to baseline demographics and most clinical outcomes. However, women exhibited higher baseline NfL than men. Not accounting for disease stage, men and women did not show statistical differences on cognitive, functional, or NfL trajectories. However, when accounting for disease stage, there was a significant interaction between baseline disease stage, sex, and time on cognitive, NfL, and functional trajectories. While sex differences were not statistically significant among asymptomatic carriers, women with MCI/dementia evidenced more rapid cognitive, NfL and functional decline over time compared to men. To evaluate the role of pathology burden, we tested the interaction between baseline NfL, sex, and time on clinical outcomes stratified by disease stage. In asymptomatic participants, women showed an attenuated adverse relationship between baseline NfL and clinical trajectories compared to men. No statistically significant sex differences were evident in the relationship between baseline NfL and clinical outcomes in participants with MCI/dementia.ConclusionIn familial FTD, women evidenced steeper clinical declines than men after symptom onset. Accounting for pathology, baseline NfL was a stronger predictor of clinical decline in asymptomatic men compared to women. NfL may be a less sensitive prognostic tool for clinical progression in women with FTD, particularly early in disease. This may reflect early “cognitive resilience” to neurodegeneration in women.