Cognitive Ability in Early Adulthood and Risk of 5 Specific Psychiatric Disorders in Middle Age

Abstract

Context Lower cognitive ability is a risk factor for some forms of psychopathology, but much of the evidence for risk is based on individuals who required specialist care. It is unclear whether lower ability influences the risk of particular patterns of comorbidity. Objective To examine the relation between premorbid cognitive ability in early adulthood and the risk of major depression, generalized anxiety disorder (GAD), posttraumatic stress disorder (PTSD), alcohol and other drug abuse or dependence, and comorbid forms of these conditions in midlife. Design Prospective cohort study in which cognitive ability was measured on enlistment into military service at a mean age of 20.4 years and psychiatric disorder was assessed by structured diagnostic interview at a mean age of 38.3 years. Setting The United States. Participants A total of 3258 male veterans, participants in the Vietnam Experience Study. Main Outcome Measures Major depression, GAD, PTSD, and alcohol or other drug abuse or dependence since enlistment and currently, diagnosed according to the DSM-III. Results Lower cognitive ability was associated with an increased risk of depression, GAD, alcohol abuse or dependence, and PTSD and with some patterns of comorbidity. For a 1-SD decrease in cognitive ability, unadjusted odds ratios (95% confidence interval) for having these disorders currently were 1.32 (1.12–1.56) for depression, 1.43 (1.27–1.64) for GAD, 1.20 (1.08–1.35) for alcohol abuse or dependence, 1.39 (1.18–1.67) for PTSD, 2.50 (1.41–4.55) for PTSD plus GAD, 2.17 (1.47–3.22) for PTSD plus GAD plus depression, and 2.77 (1.12–6.66) for all 4 disorders. Most associations remained statistically significant after adjustment for confounders. Conclusions Lower cognitive ability is a risk factor for several specific psychiatric disorders, including some forms of comorbidity. Understanding the mechanisms whereby ability is linked to individual patterns of psychopathology may inform intervention.

Pre-trauma verbal ability at five years of age and the risk of post-traumatic stress disorder in adult males and females

“…In addition to the above inconsistency, civilian studies have found that cognitive ability plays a role in the development of many types of psychopathology (Gale, et al, 2008;Glaser, et al, 2011;Hatch, et al, 2007;Koenen, et al, 2009). Therefore, we must consider that the association we found may be part of a broader relationship by which cognitive ability plays a dynamic role in the development of many psychopathologies across the lifespan.…”

“…Some of these studies suggest that higher cognitive ability may allow the individual to better translate their trauma into a narrative, and in this way make meaning of the experience, allowing the individual to overcome the trauma (Gilbertson, et al, 2006;Kremen, et al, 2007;Macklin, et al, 1998). While we might expect an increased verbal ability to assist an individual in making meaning of their trauma, our finding that cognitive ability predicts PTSD in females only is difficult to interpret, as these military studies have demonstrated strong associations exist in males (Gilbertson, et al, 2006;Kremen, et al, 2007;Macklin, et al, 1998).In addition to the above inconsistency, civilian studies have found that cognitive ability plays a role in the development of many types of psychopathology (Gale, et al, 2008;Glaser, et al, 2011;Hatch, et al, 2007;Koenen, et al, 2009). Therefore, we must consider that the association we found may be part of a broader relationship by which cognitive ability plays a dynamic role in the development of many psychopathologies across the lifespan.…”

“…We constructed birth weight z-scores which were internally adjusted for gender and gestational age as a crude measure of fetal development. Birth weight and gestational age (in weeks) were taken from obstetric records at the time of birth, along with maternal age at birth and parity.We selected other covariables based on the previous prospective and military studies (Breslau, et al, 2006;Gale, et al, 2008;Gilbertson, et al, 2006;Koenen, et al, 2007;Kremen, et al, 2007;Macklin, et al, 1998;Marx, et al, 2009;Storr, et al, 2007;Thompson Gottesman, 2008). Internalising and externalising behaviour problems were assessed in the offspring at 5 years using a shortened version of the child behaviour checklist (CBCL) (Achenbach, 1991a) completed by mothers, fully described elsewhere (Bor et al, 1997).…”

The Effect of Armed Forces Qualification Test Score on Mental Health Outcome Following Mild Traumatic Brain Injury

“…[37][38][39] Otherwise stated, higher intelligence leads to a reduced risk of cognitive deficit following brain injury, which is a predictor of mental health morbidity. [13][14][15][16][17] This hypothesis may be one explanation for how patients with a similar severity of brain injury can develop varying degrees of outcomes. 37 A recent study among Vietnam veterans also had findings indicative of the cognitive reserve mechanism; in this study, Raymont et al found that higher preinjury intelligence (measured by AFQT) was protective against later cognitive decline in veterans with a head injury, though not in an uninjured comparison group.…”

“…[7][8][9][10][11][12] Various studies in both military and nonmilitary samples have identified intelligence as a correlate of psychological outcomes. [13][14][15][16][17] Kremen et al found that Vietnam veterans in the highest quartile of cognitive ability had a 48% lower risk of PTSD compared with the lowest quartile. 13 Similarly, in a civilian study, lower childhood intelligence quotient (IQ) was associated with increased risk of adult mental health disorders, such as depression and anxiety.…”