Final answer:
Major depressive disorder (MDD) is the highest prevalence psychiatric disorder characterized by persistent feelings of sadness and hopelessness. It affects a significant number of individuals worldwide and has a major impact on their lives.
Step-by-step explanation:
The highest prevalence psychiatric disorder is major depressive disorder (MDD). MDD is a complex chronic illness that affects a significant number of individuals worldwide. It is characterized by persistent feelings of sadness, hopelessness, and a loss of interest or pleasure in activities. The point prevalence of MDD ranges around 4-7% and the lifetime prevalence estimate is about 15-20%. This disorder has a significant impact on individuals' lives and is a major cause of disability.