Major Depressive Disorder (MDD) is characterized by overwhelming feelings of sadness or despair, isolation, and a diminished interest in activities that used to bring pleasure. Because the word “depression” is used so often in our society, MDD is also generally characterized by what it is not: it is not the normal sadness or loneliness that everyone feels from time to time. It is not just feeling down in the dumps. It is not grief. Someone grieving the loss of a loved one may experience the same symptoms as a person with MDD, but in that context such symptoms are considered to be a normal and healthy response. Depression is one of the most common forms of mental illness; affecting more than 350 million people worldwide. It impacts every aspect of a person’s life and significantly impairs functioning, including work, relationships, social interactions, feelings, cognitive abilities, eating, sleeping, and physical health. Women experience depression more often than men, and experience more severe forms of depression.
Signs of MDD
For a MDD diagnosis, all signs of depression must be observable almost every day for nearly all of the day, for at least two weeks. MDD doesn’t come and go or significantly fluctuate; it is a persistent and intense pattern of thought, emotion, and behavior. It is important to note that symptoms must be significant deviations from each individual’s “normal” patterns of behavior (but one person’s normal may be markedly different from someone else’s).
May look like:
- Depressed mood (may present as irritability in childhood or adolescence).
- Persistent marked diminished interest or pleasure in almost all activities.
- Significant and unexplained weight loss or gain.
- Inability to sleep, or sleeping all day long.
- Unintentional and purposeless motions, or reduction of usual movements (people normally shift weight, cross and uncross legs, get up to walk around periodically, etc.).
- Fidgeting, or seeming drained of energy.
May feel like:
- Intense or deep feelings of sadness, emptiness, or hopelessness.
- No longer enjoying activities that used to seem interesting or pleasurable.
- Marked increase or decrease in appetite.
- Restless and/or agitated, or constantly exhausted and/or drained of all energy.
- Difficulty thinking or concentrating, or indecisiveness.
- Feelings of worthlessness or excessive/inappropriate guilt/regret (which may be delusional).
- Recurrent thoughts of death, suicidal ideations without a specific plan, specific plans to commit suicide, or attempting suicide.
If a person has depression symptoms that last for years rather than the months that MDD can last, he or she may receive a diagnosis of Persistent Depressive Disorder (PDD). Sometimes symptoms may be as severe as in MDD (previously called chronic major depressive disorder) and other times they may be slightly less intense (previously called dysthymic disorder). Dysthymia is characterized by not being able to feel “good” or whole.
How MDD Might Impact Behavior
People with MDD may feel frustrated, angry, or desperate. The overwhelming majority of people with depression are neither violent nor criminal. That said, some studies have found that persons with depression are more likely to commit violent crimes than the general population. Overall, research has been inconclusive regarding whether MDD leads directly to violent criminal behavior, or whether additional factors, such as poverty, unemployment, early childhood trauma, or drug use might cause both MDD and correlate with a higher likelihood of exhibiting criminal conduct.
People with MDD may use illegal or addictive substances as means of self-medicating if they are not receiving appropriate or complete treatment. Individuals using addictive substances have an extremely high rate of interaction with the criminal justice system, and even violent criminal behavior. On the other hand, perhaps surprisingly, some statistics suggest that illegal drug use decreases the rates of violent crimes by those with MDD. Antidepressants can be very important to the treatment of MDD, but some studies have shown that the risk of violence against self or others may increase in young people who take antidepressants.
Resources for Additional Information
 Depression and violence: a Swedish population study, Fazel, Seena et al., The Lancet Psychiatry, Volume 2, Issue 3 , 224 – 232, March 2015.
 Molero, Yasmina et al., “Selective Serotonin Reuptake Inhibitors and Violent Crime: A Cohort Study,” Ed. Alexander C. Tsai. PLoS Medicine 12.9 (2015).
Download the Fact Sheet
The CCRI worked with the Bazelon Center for Mental Health Law to produce this Fact Sheet in 2017. Please note that this document only offers an overview and simply serves as a starting point in considering the impacts of a particular condition on an individual. This Fact Sheet does not provide the level of detail, citations, medical terminology, or full diagnostic criteria that an expert or medical professional would need to make a diagnosis or that a lawyer would need to have to advocate most effectively on behalf of her client.