Autonomic nervous system correlates of past and prospective suicidal thoughts and behaviors in Mexican-origin youth.

Few studies have examined prospective or neurobiological predictors of suicidal thoughts and behaviors (STB) in Latino youth. We hypothesized that autonomic nervous system (ANS) activity at baseline and in response to social exclusion would distinguish Mexican-origin adolescents with versus without histories of suicidality, and would predict subsequent suicidality. Skin conductance responses and respiratory sinus arrhythmia, indicators of sympathetic and parasympathetic activity, respectively, were recorded at baseline and during Cyberball exclusion trials, in 229 Mexican-origin youths (M = 17.16 years, 110 females). STB was assessed 11 times across ages 10 to 20 years; 62 youths had histories of STB prior to the physiological measures, and 61 youths reported STB in the following 2.5 years. Cyberball elicited parasympathetic withdrawal without sympathetic activation, compared to baseline. Adolescents with histories of STB, compared to those without, had lower sympathetic activity during baseline and social exclusion. Lower basal sympathetic activity paired with greater uncoupled sympathetic activation during Cyberball predicted prospective STB. These findings support bioecological theories of stress vulnerability that suggest acute autonomic activity may serve as a biomarker for suicidality risk and extend prior work by identifying pathophysiology that could be the target of interventions to reduce risk in Mexican-origin youth.