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ABSTRACT: Recent reports have linked cognitive ability (IQ) with alcohol dependency, but the relationship with illegal drug use is not well understood.
Participants were 14,362 male US Vietnam veterans with IQ test results at entry into military service in 1965-1971 (mean age 22.58) who participated in a telephone interview in 1985-1986. A structured diagnostic telephone interview was used to ascertain habitual drug use during military service (for once a week, ≥ 3 months) and in civilian life (in the past 12 months, ≥ once a week), combat exposure, and post-traumatic stress disorder according to established Diagnostic and Statistical Manual of Mental disorders criteria (version III).
In unadjusted analysis, men with high IQ scores were less likely to be habitual users of cannabis (OR=0.89, 95% CI=0.86, 0.93), cocaine (OR=0.69, 95% CI=0.61, 0.78), heroin (OR=0.80, 95% CI=0.73, 0.88), amphetamines (OR=0.90, 95% CI=0.83, 0.98), barbiturates (OR=0.79, 95% CI=0.72, 0.86) and LSD (OR=0.91, 95% CI=0.82, 0.99) during military service and civilian life. These associations were markedly attenuated after adjustment for socioeconomic status in early and later civilian life.
In this cohort, socioeconomic position might lie on the pathway linking earlier IQ and later habitual drug use but might also act as a surrogate for IQ. This suggests interventions to prevent drug use could attempt to improve early life IQ and opportunities for employment.
Drug and alcohol dependence 04/2012; 125(1-2):164-8. · 3.60 Impact Factor
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ABSTRACT: Reduced lung function has been linked to poorer cognitive ability later in life. In the present study, the authors examined the converse: whether there was a prospective association between cognitive ability in early adulthood and lung function in middle age.
Participants were 4256 male Vietnam-era US veterans. Cognitive ability was assessed by the Army General Technical Test on enlistment when participants were, on average, 20 years old (range: 17-34). Data on ethnicity and place of service were extracted from army files. Smoking behaviour, alcohol consumption, basic socio-demographics and whether participants had a physician-diagnosed chronic disease were determined by telephonic interview in middle age in 1985. Forced expiratory volume in one second (FEV(1)) was measured by spirometry at a 3-day medical examination in 1986. Height and weight were also measured.
In linear regression models, poor cognitive ability in early adulthood was associated with reduced lung function in middle age, first adjusting for age and height, β=0.17, p<0.001, then additionally adjusting for circumstantial, socio-demographic, lifestyle and health factors, β=0.12, p=0.001. The same results were obtained when the analysis was confined to non-smokers.
Not only is lung function related to subsequent cognitive ability, but poor cognitive ability earlier in life is also associated with reduced lung function in middle age.
Thorax 06/2011; 66(10):884-8. · 6.84 Impact Factor
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ABSTRACT: We examined the prospective association between cognitive ability in early adulthood and erythrocyte sedimentation rate, a marker of inflammation, in middle age. Participants were 4256 male Vietnam era US veterans. Data on cognitive ability, assessed by the Army General Technical Test, ethnicity, and place of service were extracted from enlistment files. Smoking behaviour, alcohol consumption, basic socio-demographics, and whether participants suffered from a physician diagnosed chronic disease were determined by telephone interview in middle-age in 1985. Erythrocyte sedimentation rate, cholesterol, blood pressure, height, and weight were measured at a 3-day medical examination in 1986. In linear regression models that adjusted for age and then additionally for circumstantial, socio-demographic, lifestyle, and health factors, poor cognitive ability in early adulthood was associated with greater erythrocyte sedimentation rate in middle age, β=-.09. Thus, it would appear that not only does systemic inflammation influence cognition, but also that poor cognitive ability earlier in life is associated with inflammation in middle-age.
Brain Behavior and Immunity 09/2010; 25(2):298-301. · 4.72 Impact Factor
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ABSTRACT: The aim of this study was to examine the explanatory power of intelligence (IQ) compared with traditional cardiovascular disease (CVD) risk factors in the relationship of socio-economic disadvantage with total and CVD mortality, that is the extent to which IQ may account for the variance in this well-documented association.
Cohort study of 4289 US male former military personnel with data on four widely used markers of socio-economic position (early adulthood and current income, occupational prestige, and education), IQ test scores (early adulthood and middle-age), a range of nine established CVD risk factors (systolic and diastolic blood pressure, total blood cholesterol, HDL cholesterol, body mass index, smoking, blood glucose, resting heart rate, and forced expiratory volume in 1 s), and later mortality. We used the relative index of inequality (RII) to quantify the relation between each index of socio-economic position and mortality. Fifteen years of mortality surveillance gave rise to 237 deaths (62 from CVD and 175 from 'other' causes). In age-adjusted analyses, as expected, each of the four indices of socio-economic position was inversely associated with total, CVD, and 'other' causes of mortality, such that elevated rates were evident in the most socio-economically disadvantaged men. When IQ in middle-age was introduced to the age-adjusted model, there was marked attenuation in the RII across the socio-economic predictors for total mortality (average 50% attenuation in RII), CVD (55%), and 'other' causes of death (49%). When the nine traditional risk factors were added to the age-adjusted model, the comparable reduction in RII was less marked than that seen after IQ adjustment: all-causes (40%), CVD (40%), and 'other' mortality (43%). Adding IQ to the latter model resulted in marked, additional explanatory power for all outcomes in comparison to the age-adjusted analyses: all-causes (63%), CVD (63%), and 'other' mortality (65%). When we utilized IQ in early adulthood rather than middle-age as an explanatory variable, the attenuating effect on the socio-economic gradient was less pronounced although the same pattern was still present.
In the present analyses of socio-economic gradients in total and CVD mortality, IQ appeared to offer greater explanatory power than that apparent for traditional CVD risk factors.
European Heart Journal 09/2009; 30(15):1903-9. · 10.48 Impact Factor
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ABSTRACT: (i) examine the relation, if any, of pre-morbid IQ scores at 20 years of age with the risk of later cancer mortality; and (ii) explore the role, if any, of potential mediating factors (e.g. smoking, obesity), assessed in middle age, in explaining the IQ-cancer relation.
Cohort study of 14, 491 male, Vietnam-era, former US army personnel with IQ test scores at around 20 years of age (1965-71), who participated in a risk factor survey at around age 38 years of age (1985-6), who were then followed up for mortality experience for 15 years.
There were 176 cancer deaths during mortality surveillance. We found an inverse association of IQ with later mortality from all cancers combined (age-adjusted HR(per one SD decrease in IQ); 95% confidence interval: 1.27; 1.10, 1.46) and smoking-related malignancies (1.37; 1.14, 1.64). There was some attenuation following control for mediating variables, particularly smoking and income, but the gradients generally held at conventional levels of statistical significance.
Higher scores on pre-morbid IQ tests are associated with lower risk of later cancer morality. The strength of the relation was partially mediated by established risk factors.
Psycho-Oncology 02/2009; 18(10):1122-6. · 3.34 Impact Factor
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ABSTRACT: 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.
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.
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.
The United States.
A total of 3258 male veterans, participants in the Vietnam Experience Study.
Major depression, GAD, PTSD, and alcohol or other drug abuse or dependence since enlistment and currently, diagnosed according to the DSM-III.
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.
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.
Archives of general psychiatry 01/2009; 65(12):1410-8. · 12.26 Impact Factor
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ABSTRACT: Lower IQ test scores are related to an increased risk of violent assault. We tested the relation between IQ and death by homicide. In a prospective cohort study of 14,537 men (21 homicides), the association between lower IQ and an increased risk of homicide was lost after multiple adjustment.
Psychiatry Research 09/2008; 161(1):112-5. · 2.52 Impact Factor
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ABSTRACT: Examine the relation between IQ in early adulthood and later coronary heart disease (CHD) mortality, and assess the extent to which established risk factors measured in middle-age might explain this gradient.
Cohort study of 4316 male former Vietnam-era US army personnel with IQ scores (mean age 20.4 years), risk factor data (mean age 38.3 years) and 15 years mortality surveillance.
In age-adjusted analyses, lower IQ scores were associated with an increased rate of CHD mortality (hazard ratio per SD decrease in IQ; 95% confidence interval: 1.34; 1.00, 1.79). Adjustment for later chronic disease (1.22; 0.91, 1.64), behavioural (1.29; 0.95, 1.74) and physiological risk factors (1.19; 0.88, 1.62) led to some attenuation of this gradient. This attenuation was particularly pronounced on adding socioeconomic indices to the multivariable model when the IQ-CHD relation was eliminated (1.05; 0.73, 1.52). A similar pattern of association was apparent when cardiovascular disease was the outcome of interest.
High IQ may lead to educational success, well remunerated and higher prestige employment, and this pathway may confer cardio-protection.
European Journal of Cardiovascular Prevention and Rehabilitation 06/2008; 15(3):359-61. · 2.63 Impact Factor
