Causes
The exact cause of dysthymia is not known, but it is thought to be a combination of factors that play a role in its development. Heredity (genetics) can play a role, and people with family members who have depression or dysthymia are more likely to experience dysthymia, especially when it starts early in life (teens to early 20s).
Changes in neurotransmitters (chemical messengers) in the brain may also precipitate dysthymia. Chronic stress or medical illness, social isolation, and thoughts and perceptions about the world, can all influence the development of dysthymia. Other mental health conditions (e.g., borderline personality disorder) can also increase the risk of its development.
About 1 out of 4 people with dysthymia develop the condition in midlife, known as late-onset dysthymia. Symptoms usually follow a particular depressive episode, related to some shock or loss a person has experienced.