Physical activity, muscular strength, and depression symptoms among adultsA cross-sectional and prospective population-based study

Zusammenfassung

Depression is a mental disorder that affects more than 300 millions people wordwide. The highest prevalence rates of depression are observed at the age of 55-74 years, but the greater dysfunction occurs over 60 years. The most common treatment for depression includes pharmacotherapy and psychotherapy, which can be expensive for health care systems due to the high prevalence of the disorder. To address the health problem of depression that affects so many people around the world, it is important to identify additional and effective treatment options. Physical activity and physical fitness are important factors that contribute to improving health, regardless of age. Regular physical activity is associated with reducing the risk of all-cause mortality and several chronic medical conditions. Physical activity and physical fitness are also associated with mental health and depression. There is evidence that supports the notion that physical activity can confer protection against depression. Among older people, physical activity can be considered as a non-medication alternative to antidepressants and seems that there is an underestimation of the positive clinical effects. Therefore, this thesis aimed to analyse, cross-sectional, and prospectively, the relationship between physical activity, muscular strength, and depression symptoms, stratified by sociodemographic characteristics of adults and older adults. For the studies, it was used data from the Survey of Health, Aging, and Retirement in Europe (SHARE) study, and from the European Social Survey project. SHARE is a cross national panel database of information on a wide range of variables spanning from health behaviour and psychological health to socioeconomic status and social and family networks. The European Social Survey is an academically driven cross-national survey that has been conducted every two years across 20 European countries and Israel. Depression symptoms were assessed using the EURO-D 12-item scale and the Centre for Epidemiological Studies Depression Scale (CES-D8). Physical activity was self-reported. Muscular strength was measured using a dynamometer. Participants reported their sex, age, educational level, marital status, living place, household income, and chronic diseases. Body mass index was calculated from self-reported height and weight (kg/m2). Participants were asked about their smoking behavior and alcohol consumption. From the studies’ results, it was observed that engaging in leisure-time physical activity was negatively and linearly related to depressive symptoms, independently of sex or age. Men and women engaging in moderate or vigorous physical activity once or more than once a week had fewer depression symptoms than those who engage less than once a week. Furthermore, engaging in moderate and vigorous physical activity decreased the odds of depression compared to engaging in physical activity less than once a week. Men and women with more grip strength were less likely to have depression symptoms than those with less grip strength. The negative relationship between strong grip strength and depression symptoms was observed among men and women under and over 65 years. These study’s results support the documented benefit of physical activity on depression symptoms. It adds to the literature that this relationship is regardless of sociodemographic characteristics. The benefits of physical activity on depression are transversal and physical activity can be recommended for most people for the prevention or treatment of depression.