Epidemiology is the study of the distribution and determinants of disease frequency in human populations (McMahon & Pugh).

Study results are from 2 epdemiologic surveys:
Epidemiologic Catchment Area (ECA) study of early 80’s and (b) National Comorbidity Survey (NCS) of early 1990’s. Used DSSM categories.
For adults:
SIMPLE PHOBIA (8.3%) and ANY MOOD DISORDER (7.1%) lead.

For children ages 9-17:
ANXIETY DISORDERS (13%) and DISRUPTIVE DISORDERS (10%) lead.