Is major depressive disorder a mental illness?

Generally speaking, major depressive disorder falls within the category of mental illness, but it is not the traditional type of psychosis characterized by hallucinations, delusions, or other severe thought disturbances. If there are concerns, it is recommended to seek medical consultation early. The detailed analysis is as follows:

In medical terms, mental illness is a broad category that includes various conditions such as depression, anxiety disorders, and schizophrenia. Major depressive disorder is classified as a "mood disorder" within mental illnesses due to its core symptoms—persistent low mood, loss of interest, and exhaustion of energy—and its significant impact on cognitive and social functioning. It differs from psychotic disorders like schizophrenia, which primarily involve disorganized thinking and perceptual abnormalities.

Individuals with major depressive disorder mainly exhibit emotional and behavioral abnormalities, such as persistent feelings of hopelessness, self-criticism, and severe disruptions in sleep and appetite. Some patients may experience brief cognitive distortions, but hallucinations and delusions—symptoms indicative of psychosis—are rare. In contrast, traditionally defined psychosis typically involves fragmented thinking, distorted perception, and uncontrolled behavior, with patients often lacking insight into their condition—features that clearly differentiate it from the core symptoms of major depressive disorder.

If you notice symptoms related to major depressive disorder in yourself or someone close to you, it is important to promptly visit a psychiatric or psychological clinic for an accurate diagnosis and standardized treatment. During treatment, close attention should be paid to emotional changes to avoid delayed intervention due to misunderstanding the nature of the illness, while also providing sufficient emotional support to the patient.