Impulsivity as a risk factor for suicidal behavior

Impulsivity is a complex behavioral construct. Action without planning or reflection is central to most definitions of impulsivity. Thus, impulsivity appears to be associated with a failure of behavioral filtering processes outside of consciousness, with compromised ability to reflect on impending acts or to use knowledge and intelligence to guide behavior. Impulsive behavior, including aggression and suicide attempts, differs from corresponding premeditated behavior by having an inappropriately short threshold for response, lack of reflection, lack of modulation, and lack of potential gain, leading potentially to dissociation between an action and its intent. Impulsivity is a prominent and measurable characteristic of bipolar disorder that can contribute to risk for suicidal behavior. The purpose of this study was to investigate the relationship between impulsivity and severity of past suicidal behavior, a potential predictor of eventual suicide, in patients with bipolar disorder. Although the screening of BD patients for the risk factors is not foolproof, the consideration of those risk factors is an important component of the clinical assessment of suicidal risk. The clinical unpredictability can be especially challenging with BD patients, given the sometimes rapid shifts in mood (lability), strong reactivity to losses, frustrations or other stressors, impulsivity, disinhibiting effects of commonly abused central depressants including alcohol, comorbid anxiety disorders, and potential adverse effects of excessive use of antidepressants. Impulsivity/aggression has been reported to be related to suicidal behavior in several studies. For example, Mann and colleagues proposed a stress-diathesis model of suicidal behavior. Impulsivity, related to a genetic predisposition and dysfunction of the suicidal ideation to act upon their impulse. Higher aggression may also contribute to the increased lethality of suicide attempts. Among all psychiatric disorders, BD carries the highest suicide risk. There is no good explanation as to why BD patients kill themselves more than patients with MDD or schizophrenia. Possibly BD patients are are more prone to dysphoric-irritable mixed states associated with higher degree of discontent and impulsivity. Impulsivity is also a relevant clinical factor in suicidal behavior and is a common trait among persons with BD. However, impulsivity has been tentatively associated primarily with suicide attempts of limited lethality rather than with completed suicide. It is not clear whether relatively high rates of illness recurrence or the presence of rapid cycling (more than four recurrences within a year) increases risk of suicide in mood disorders. There may also be a genetic predisposition to suicide, but it has not been proven that this risk is independent of the risk for BD or depressive illness.