Social epidemiology is a branch of epidemiology that focuses particularly on the effects of social-structural factors on states of health. Social epidemiology assumes that the distribution of advantages and disadvantages in a society reflects the distribution of health and disease. It proposes to identify societal characteristics that affect the pattern of disease and health distribution in a society and to understand its mechanisms. The central and initial question of social epidemiology to be answered is what effect do social factors have on individual and population health. However, the new focus on this theme using current epidemiological methods is a relatively recent phenomenon. There are several significant concepts in the field of social epidemiology: 1) the bio-psychosocial paradigm, 2) the population perspective, 3) use of new statistical approaches such as multilevel analysis, and 4) significance of theory.The relationship between social class and health has been a major research field since the beginning of public health history. Many studies have identified the disparities in health among social classes and developed several theories, such as social selection theory and socio-biological translation theory. However, despite the long history of this research field, the effect of social class on health is not yet fully understood.Income distribution and health is a relatively new field within social epidemiology. Three possible mechanisms for the consequences of income distribution on health are 1) disinvestment of human capital, 2) disinvestment of social capital, and 3) psychological process. Refining theories of income distribution is a major challenge in research on income distribution.

BACKGROUND: This study aimed to describe the status of alcohol consumption and drug use among young adults as well as their determinants. METHODS: We conducted a cross-sectional study of 356 young adults (aged 18 to 24 years) living in Palau in 2013. The prevalence of self-reported alcohol and marijuana usage were compared within and between sexes, age groups, ethnicities, and education levels. RESULTS: The proportion of current drinking was higher in people aged 21-24 than in those aged 18-20 (73.2% vs. 60.9%, p = 0.09 in men and 48.3% vs. 30.0%, p = 0.02 in women), while that of marijuana use did not differ between the age groups. The proportions of current drinking and marijuana use were higher in Palauan than in other ethnicities (current drinking: 70.6% vs. 40.6%, p = 0.005 in men and 38.8% vs. 16.6%, p = 0.04 in women; lifetime marijuana use: 80.0% vs. 52.9%, p = 0.02 in men and 56.1% vs. 30.6%, p = 0.09 in women). The proportion of frequent (3 times or more) marijuana users was higher for the lower educated than for the higher educated (62.5% vs. 32.1%, p < 0.001 in men and 33.9% vs. 24.4%, p = 0.12 in women). CONCLUSIONS Sex, age, ethnicity, and education were significant determinants of alcohol and marijuana use.
Age Factors ; Alcohol Drinking/ethnology* ; Cross-Sectional Studies ; Educational Status ; Female ; Humans ; Male ; Marijuana Use/ethnology* ; Palau/epidemiology* ; Prevalence ; Sex Factors ; Young Adult