Abstract
To the Editor
The diagnosis of post-traumatic stress disorder (PTSD) is common in patients who develop hyperarousal symptoms (irritability, hypervigilance, anxiety, etc.), nightmares, flashbacks, and avoidant behavior in response to a traumatic experience involving, for example, combat, partner or parental abuse, or street violence. PTSD is strongly associated with a wide spectrum of clinical and social impairments that can dramatically decrease one’s quality of life. A striking clinical feature of PTSD is an increased risk of suicidal behavior, i.e. suicidal ideation, suicide attempt, and completed suicides (Sareen et al., 2005).
The relationship between PTSD and suicidal behavior is quite complex, with mounting data indicating a high degree of psychiatric and medical comorbidities in this patient population, and each co-occurring disorder representing an independent risk factor for suicidal behavior. Depression, a frequent psychiatric comorbidity of PTSD, has been shown to be associated with a high rate of suicide attempts and completed suicides (Sareen et al., 2007). Compared to the general population, individuals with PTSD are also more prone to respiratory, cardiovascular, neurological, and rheumatological disorders; all conditions with an elevated suicide risk as exemplified by data on hospitalized patients with non-psychiatric illnesses who demonstrate an 8 times higher rate of suicide (Tseng et al., 2011).
Given that PTSD and other medical illnesses separately contribute to suicide risk, we hypothesize that the risk of suicidal behaviour in patients with concomitant PTSD and medical illnesses is different from that in patients with either disorder alone. For example, one study demonstrated that the odds ratio for suicide attempt in patients with comorbid PTSD and traumatic brain injury was 3.3 times that for traumatic brain injury alone, and 0.94 times that for PTSD alone (Brenner et al., 2011). Cancer patients with acute stress disorder are at an increased risk for suicidal ideation compared to those without it (McGarvey et al., 1998). Several similar studies point to the same unique clinical entity – a correlation between PTSD, associated medical illnesses, and the risk of suicidal behavior. However, this field of research is still in its infancy. Many questions about the rate or pattern of suicidal behavior in patients with comorbid PTSD and medical disorders are yet to be addressed. For example, does the risk of suicide increase, decrease, or remain unchanged by a particular medical comorbidity? If the risk of suicidal behavior does indeed increase in comorbid PTSD, compared to each diagnosis alone, is the increase additive or synergistic? Given the medical, social, and economic implications of suicide, future studies must address these questions, and, in the process, create a new interdisciplinary area of research with the long-term goal of decreasing the risk of suicidal behavior in patients with comorbid PTSD and medical illnesses.