Obesity Epidemiology

362 EPIDEMIOLOGIC STUDIES OF DETERMINANTS OF OBESITYinvestigated individuals in the general population. Given the intent of this chapter, wehave primarily focused on the latter in the forthcoming discussion. Next, one must beparticularly careful about terminology and measurement in this area. The term depressionhas been used widely to describe general negative affect, the presence of depressive symptoms(without a diagnosis), and major depressive disorder. Assessment strategies have beensimilarly varied, from short self-report scales of negative affect and mood to structuredinterviews, designed with the express purpose of making a psychiatric diagnosis.The overwhelming majority of studies investigating this question have focused ondepression or the negative effect experienced as a consequence of obesity. 204-206 Despitethis intent, many of these studies have also been cross-sectional in nature, which hasallowed the question of causality to linger. There have been a number of cross-sectional,general population studies showing a significant positive association between obesityand depression. 207-217 Kress et al., 210 for example, found in cross-sectional data collectedfrom 10,400 active duty U.S. service personnel, a significant positive relation betweenobesity and depression symptoms among both men and women; women, however, hada 3-fold increased odds of depressive symptoms. Similarly, Jorm et al. 218 showed, in across-sectional investigation among Australian residents, that depressive symptoms andobesity were positively associated among women, but weakly among men. However,after adjusting for potential mediators (e.g., physical health, physical activity, social support,and socioeconomic resources) the association weakened considerably. Haukkalaand Uutela 219 administered the widely used Beck Depression Inventory (BDI) among3,361 men and women, aged 25 to 64 years, and found a significantly positive relationbetween higher BDI scores, waist-hip ratio and BMI, though only among women.Carpenter et al. 214 measured major depression in the last year (as well as suicidal ideationand suicide attempts), diagnosed using the Diagnostic and Statistical Manual ofMental Disorders (DSM-IV) guidelines. They found that the pattern of results differedby gender, such that there was a positive association of increased BMI with both amajor depression diagnosis and suicidal ideation among women. However, among men,major depression, suicide attempts, and suicidal ideation were associated with lowerBMI. Together, the assembled studies are quite varied in approach 220 and the magnitudeof these associations has generally been small; 220 some studies have shown an inverserelation, 221 and others have shown null results. 222,223 This has highlighted the need forprospective studies to investigate the association between depression and obesity, withparticular attention to temporal ordering.Only a handful of prospective investigations in this area have been conducted. 224,225 Inone of the earliest, Pine et al. 226 administered psychiatric interviews to a sample of 776adolescents in 1983 (aged 9 to 18 years) and followed them again in 1992, when theywere aged 17 to 28 years. They found a positive relation between baseline depressionlevels and BMI; however, the association did not persist after adjustment for covariates.These findings were consistent with a smaller clinical study, 227 conducted by the sameresearch group, which followed children aged 6 to 17 years who had either a depressiondiagnosis or no diagnosis. Over 10 to 15 years of follow-up, participants with a childhooddepression diagnosis had significantly greater adulthood BMI. Most recently, theresearch group 228 studied a prospective cohort of 591 individuals (followed between agesof 19 and 40 years), who were administered clinical interviews to assess depression.After adjustment for multiple covariates, findings suggested that a diagnosis of depressionbefore age 17 was associated with increased weight gain during adulthood and obesityamong women, but not men. These findings were consistent with another prospectivestudy conducted among a birth cohort of New Zealand residents, which found that at26 years of follow-up, adolescent depression was associated with a significantly greater