The article also compared symptoms between unipolar depression and bipolar depression:

Unipolar Depression and Bipolar Depression shared the following symptoms:

1. Feelings of hopelessness, pessimism
2. Feelings of guilt, worthlessness, helplessness
3. Difficulty concentrating
4. Loss of interest or pleasure in hobbies and activities that were once enjoyed
5. Difficulty sleeping
6. Overeating or loss of appetite
7. Persistent aches or pains, headaches, cramps, or digestive problems that do not ease even with treatment
8. Thoughts of suicide, suicide attempts.

The additional symptoms for bipolar depression included the following:

1. More suicide attempts than with major depressive disorder
2. A profound loss of energy.
3. Severe depression more likely to include psychotic symptoms
4. Onset of depression at a younger age
5. More likely to have a co-occurring mental illness, such as OCD, panic disorder or substance abuse.
6. More episodes of depression than with unipolar depression
7. Use of antidepressant without a mood stabilizer may cause hypomania or mania.