Poster E13, Monday, March 26, 2:30-4:30 pm, Exhibit Hall C
Amygdala activation as a predictor of fragile X-associated tremor/ataxia syndrome onset
Emily Fourie1, Annie Shelton1, David Hessl1,2, Susan, M Rivera1,2; 1University of California, Davis, 2UC Davis MIND Institute
Individuals with premutation alleles (55–200 CGG repeats) of the fragile X mental retardation 1 (FMR1) gene are at risk for developing a neurodegenerative disease, fragile X-associated tremor/ataxia syndrome (FXTAS). The disease has a variable penetrance, but prodromal markers have not yet been identified. The goal of this study was to determine whether differential activation in the amygdala can be predictive of conversion to FXTAS. We performed functional magnetic resonance imaging during an emotion-matching task on a group of 30 adult male premutation carriers and 13 age- and IQ-matched controls at two longitudinal time points. The carriers were further divided into three subgroups: those who had FXTAS at time 1—T1 converters (N=9); those who developed FXTAS by time 2—T2 converters (N=10); and those who showed no signs of FXTAS at either time, non-converters (N=11). We extracted the mean amygdala activation using a region of interest approach (6 mm spheres around the foci of the right and left amygdalae) and performed a repeated measures group x time ANOVA. Results show a significant group by time interaction, F(3, 37) = 4.12, p = 0.013, and pairwise comparisons revealed significant differences between T1 converters and both non-converters and controls at time 1. Furthermore, both non-converters and controls showed a significant decrease in activation between time 1 and time 2, while T1 and T2 converters did not. These findings suggest that non-converters show similar activation patterns to controls and that differences in activation may indicate which premutation carriers are at risk for conversion of FXTAS.
Topic Area: EMOTION & SOCIAL: Development & aging