Exercise behavior and mental health : A genetic perspective

Objectives To examine whether regular exercise is associated with anxiety, depression and personality in a large population-based sample as a function of gender and age. Methods The sample consisted of adolescent and adult twins and their families (N =19,288) who participated in the study on lifestyle and health from the Netherlands Twin Registry (1991-2002). Exercise participation, anxiety, depression and personality were assessed with self-report questionnaires. Results The overall prevalence of exercise participation (with a minimum of 60 minutes weekly at 4 METs (Metabolic Energy Expenditure Index)) in our sample was 51.4%. Exercise participation strongly declined with age from about 70% in young adolescents to 30% in older adults. Among adolescents, males exercised more, whereas among older adults, females exercised more. Exercisers were on average less anxious (-0.18 SD), depressed (-0.29 SD) and neurotic (-0.14 SD), more extraverted (+0.32 SD) and were higher in dimensions of sensation seeking (from +0.25 SD to +0.47 SD) than non-exercisers. These differences were modest in size, but very consistent across gender and age. Conclusions This study corroborates and extends previous findings: regular exercise is cross-sectionally associated with lower neuroticism, anxiety and depression and higher extraversion and sensation seeking in the population. DeMoor_opmaak_def_cor. indd 30 22-12-2008 10:47:07 31 Regular exercise, anxiety, depression and personality The relationship between exercise behavior and mental health has been examined by many researchers (Byrne & Byrne, 1993; Folkins & Sime, 1981; Gauvin & Spence, 1996; North et al., 1990; Salmon, 2001; Scully et al., 1998). However, population studies on the association between exercise and mental health are scarce. To our knowledge, only two large population studies have examined the cross-sectional association in both males and females across a wide age range (Farmer et al., 1988; Weyerer, 1992). Although the instruments to measure depression have greatly dif fered, and exercise was based on a single question only, these two studies converge on the main f inding that regular exercise is associated with less depression in the population. Both studies only examined the relationship between exercise and depression. The association of exercise with other prominent aspects of mental health, such as anxiety, remains unexplored in population-based samples, as does the association with personality traits. Both anxiety and depression are known to be correlated with personality, most prominently with neuroticism, but also with extraversion (Costa, Jr. & McCrae, 1980; Middeldorp et al., 2006). Because personality traits can index the risk for anxious and depressive psychopathology, they could potentially mediate the co-morbidity between exercise and anxiety and depression. Personality traits like sensation seeking seem independent of anxiety and depression, but predict lifestyle factors such as smoking or drinking (Koopmans, 1997; Vink et al., 2003) and possibly also exercise behavior. The aim of the present paper, therefore, is to examine the association of exercise with anxiety, depression and personality in a large DeMoor_opmaak_def_cor. indd 31 22-12-2008 10:47:07