The main difference between unipolar depression and bipolar depression is that bipolar depression causes periods of mania, according to ULifeline. People with unipolar depression experience low moods, but they do not have manic episodes.
People with bipolar depression experience intense mood episodes, according to the National Institute of Mental Health. Depressive episodes are characterized by intense sadness or hopelessness, while manic episodes are characterized by extreme joy or excitement. In some cases, a person with bipolar depression may experience depression and manic symptoms at the same time, which is known as a mixed state.
During a manic state, several behavioral changes occur, states the National Institute of Mental Health. Racing thoughts, restlessness and impulsive behavior are all potential signs of a manic episode. Someone experience a manic episode may also take on a lot of new projects, talk very fast or engage in high-risk activities. In contrast, a depressive episode may cause changes in eating habits, fatigue, difficulty in concentration, memory problems or difficulty making decisions.
Unipolar depression and bipolar depression do have some symptoms in common, explains ULifeline. Both types of depression cause low moods or extreme sadness. Depression causes low energy levels, loneliness, difficulty staying focused, withdrawal from one loved ones, and suicidal thoughts or feelings. Someone with unipolar depression may also report headaches or digestive problems that do not improve with treatment, reports WebMD.