Final answer:
The diagnosis of major depressive disorder requires a depressed mood, decreased pleasure in most activities, and feelings of worthlessness, among other symptoms, for at least two weeks.
Step-by-step explanation:
The diagnosis of major depressive disorder (MDD) is determined by a combination of symptoms defined in the Diagnostic and Statistical Manual of Mental Disorders (DSM). To be diagnosed with Major Depressive Disorder, the following criteria should be met:
- Depressed mood most of the day, nearly every day.
- Markedly diminished interest or pleasure in all or most activities (known as anhedonia) most of the day, nearly every day.
- Feelings of worthlessness or excessive or inappropriate guilt (which may be delusional) nearly every day.
Additional symptoms include significant weight loss or gain, insomnia or hypersomnia, psychomotor agitation or re_tardation, fatigue or loss of energy, diminished ability to think or concentrate, and recurrent thoughts of death, sui_cidal ideation, or sui_cide attempts.
It's important to note that symptoms should be present for at least two weeks and cause clinically significant distress or impairment in social, occupational, or other important areas of functioning. Having a chronic medical illness might influence the course of depression but is not a criterion for diagnosis. Increased energy is typically not associated with MDD, as many people with this disorder experience fatigue and loss of energy.