PDD is characterized by a year-long period (at minimum) of depressed or irritable mood during which at least two of the following symptoms are also present:
- Poor appetite or overeating
- Insomnia (not able to fall or stay asleep) or hypersomnia (sleeping too much) nearly every day.
- Fatigue or very low energy nearly every day.
- Low self esteem.
- Diminished ability to concentrate or trouble making decisions that was not previously present.
- Feelings of hopelessness.
During the year-long (at minimum) period, no more than two months may have been spent symptom-free. In addition, these symptoms must cause impairment in function – with one’s family, friends, or at school – and, as mentioned above, they must represent a change in functioning. It is possible that a child or adolescent would meet criteria for major depressive disorder, which has a duration criteria of two weeks, but later meet criteria for PDD if his/her symptoms persist for at least a year. In this case, the youth would be diagnosed with MDD and PDD – this is sometimes called “double depression.” Some youth may have trouble concentrating due to other factors, if symptoms of inattention or poor concentration existed prior to the depressed mood, caution must be taken in attributing them to the depressive episode. Finally, depressive symptoms may also occur within the context of a bipolar spectrum disorder, if a youth experiences a long period of depressed mood after first experiencing a period during which his/her mood was abnormally elevated and s/he had high energy or if s/he experiences days of elevated mood during the depression, it is possible that s/he is experiencing other specified bipolar disorder or cyclothymic disorder.