Reduced Vagal Tone in Women With The Premutation Is Associated With MRNA but Not Depression or Anxiety

BACKGROUND: Autonomic dysfunction is implicated in a range of psychological conditions, including depression and anxiety. The () premutation is a common genetic mutation that affects ~1:150 women and is associated with psychological vulnerability. This study examined cardiac indicators of autonomic function among women with the premutation and control women as potential biomarkers for psychological risk that may be linked to . METHODS: Baseline inter-beat interval and respiratory sinus arrhythmia (a measure of parasympathetic vagal tone) were measured in 35 women with the premutation and 28 controls. The women completed anxiety and depression questionnaires. genetic indices (i.e., CGG repeat, quantitative FMRP, mRNA, activation ratio) were obtained for the premutation group. RESULTS: Respiratory sinus arrhythmia was reduced in the premutation group relative to controls. While depression symptoms were associated with reduced respiratory sinus arrhythmia among control women, these variables were unrelated in the premutation. Elevated mRNA was associated with higher respiratory sinus arrhythmia. CONCLUSIONS: Women with the premutation demonstrated autonomic dysregulation characterized by reduced vagal tone. Unlike patterns observed in the general population and in study controls, vagal activity and depression symptoms were decoupled in women with the premutation, suggesting independence between autonomic regulation and psychopathological symptoms that is atypical and potentially specific to the premutation. The association between vagal tone and mRNA suggests that molecular variation associated with plays a role in autonomic regulation.