Introduction: Previously, we reported that slowed response speed, calculated as a composite factor across multiple speeded performance tasks, distinguished depressed suicide attempters across the lifespan. However, the relationship between slowed response speed and other clinical risk factors is unknown. Here, we examined these associations to better understand the mechanisms by which slowed response speed contributes to suicidal behavior risk.
Methods: Depressed patients with and without past suicide attempt, ages 16-80, were recruited from 3 sites (AFSP Lifespan Neurocognition study). Participants received a battery of clinical assessments including measures of depression severity, suicidal ideation, hopelessness, impulsiveness, aggression, borderline traits, entrapment, rumination, and comorbid diagnoses. Response speed factor (RSF) was derived from all speeded cognitive tasks administered (Choice Reaction Time, Coding, Stroop RT’s, A not B reasoning speed). Associations of these clinical measures with slowed response speed were analyzed.
Results: RSF (higher is worse performance) correlated most strongly with age (r=.53, p<.001), estimated intellectual ability (r= -.48, p<.001), depression severity (r=.28, p<.001), suicidal ideation severity (r=.27, p<.001), and severity of medical comorbidities (r=.45, p<.001), but no other risk factors (eg, impulsiveness, aggression, entrapment, rumination). It correlated as well with a sleep disturbance symptom factor derived from the Hamilton Depression Rating scale (HDRS) (r=.25, p<.001), and the somatic complaint factor from the Beck Depression Inventory (BDI)(r=.19, p=.006). When used in combination with other measures to predict current suicidal ideation, RSF (Beta=.173, p=.009) was included with HDRS Psychic Depression (Beta= .324, p<.001) and Sleep Disturbance (Beta=.153, p=.012) factors, BDI Self-Blame (Beta=.157, p=.026), and severity of medical comorbidity (Beta=.187, p=.005) to predict 36.2% of the variance