Final answer:
Social epidemiology is the quantitative study of how mental disorders are distributed across populations, critical for understanding and addressing these health issues.
Step-by-step explanation:
The quantitative study of the distribution of mental disorders in human populations is known as social epidemiology. This discipline investigates the patterns, causes, and effects of health and disease conditions within specified populations. Mental illnesses such as schizophrenia, major depression, bipolar disorder, anxiety disorders, and others significantly impact individuals and society, as detailed by the American Psychiatric Association in the Diagnostic and Statistical Manual of Mental Disorders (DSM). Social epidemiology helps in understanding the prevalence (morbidity) and distribution of these illnesses for better prevention and treatment strategies.