UNDERSTANDING COMMON MENTAL HEALTH DISORDERS: PREVALENCE, NEUROBIOLOGY, AND SOCIODEMOGRAPHIC CORRELATES

Abstract

Mental health disorders affect hundreds of millions of people worldwide. This review summarizes current knowledge on the prevalence, biological mechanisms, and social patterns of major depressive disorder, anxiety disorders, bipolar disorder, and schizophrenia. Major depressive disorder affects approximately 4.4% of the global population, while anxiety disorders affect 3.6% (World Health Organization, 2017). Brain imaging studies have identified structural and functional alterations in the prefrontal cortex, amygdala, and hippocampus in these conditions (Goodkind et al., 2015). Neurotransmitter systems, particularly serotonin, dopamine, and norepinephrine, show consistent dysregulation across disorders (Hyman, 2005). Sociodemographic factors including gender, income, and adverse childhood experiences strongly influence disorder risk (Kessler et al., 2010; McLaughlin et al., 2012). This overview provides a foundation for understanding mental illness as a biological and social phenomenon without discussing treatment or intervention approaches.