While major depressive disorder can be a severe medical condition, it is not considered a disease. Major depressive disorder is a common mental illness that involves frequent mood changes, diminished self-esteem and low energy. According to the American Anxiety and Depression Association of America, major depressive disorder affects approximately 16.1 million Americans, which is around 6.7 percent of the country’s adult population.
Disorder is not interchangeable with disease. According to the Diagnostic and Statistical Manual of Mental Disorders: 5th Edition (DSM-5), a disorder is a cluster of symptoms that cannot be defined by a more pervasive condition and does not have a known origination. A disease is a disorder where the origination is known.
Viral infections and Alzheimer’s are examples of diseases. Anxiety and schizophrenia are examples of disorders, which cannot be explained by a disease’s presence.
Is Major Depressive Disorder a Personality Disorder?
Major depressive disorder is not a personality disorder but rather a mood disorder. Experiencing drastic mood changes is a primary effect of depression, similar to other mood conditions such as bipolar and seasonal affective disorder.
The DSM-5 defines the criteria needed to diagnose major depressive disorder. The individual must experience either a depressed mood or a loss of interest in activities for two weeks along with at least four of the following:
- Significant weight loss or fluctuating appetite
- Slowed thought process and noticeably reduced physical movement
- Regularly feeling lethargic
- Feeling worthless or guilt
- Difficulty concentrating or making decisions
- Recurring thoughts of death or suicide
The DSM-5 defines personality disorders as impairments in self and interpersonal functioning combined with at least one abnormal personality trait. A personality disorder causes people to think, feel and behave in ways that contrast with cultural expectations, resulting in difficulties functioning within society. Types of personality disorders include:
- Paranoid personality disorder
- Schizoid personality disorder
- Antisocial personality disorder
- Borderline personality disorder
- Narcissistic personality disorder
- Avoidant personality disorder
Mood disorders can affect one’s personality, and personality disorders can impact someone’s mood. However, these are secondary outcomes often caused by the disorder’s primary effect. While major depressive disorder can affect a person’s personality, this effect occurs due to the mood change and is not a direct cause of the medical condition. Additionally, major depressive disorder can co-occur along with a personality disorder.