Violence is not usually considered to be related to depression, yet findings suggest an association between violent behavior and depression or depressive symptoms in many different disorders. A Swedish study compared the criminal records of 47,158 depressed individuals with the records of 898,454 people with no history of depression matched by age and sex.1 Those in the depressed group were approximately 3 times more likely than the general population to commit violent crimes, such as homicide, attempted homicide, aggravated assault, or robbery.
This association was present even when previous histories of violence, self-harm, psychosis, and substance use were taken into consideration. Furthermore, the risk of violent crime significantly increased in individuals with more depressive symptoms.
An association between depressive symptoms and violence in patients with schizophrenia has also been observed. In one study, 1410 patients with schizophrenia were clinically assessed and interviewed about violent behavior in the past 6 months.2 Serious violence was associated with depressive symptoms and with substance abuse. In another study, patients with schizophrenia who were physically violent were compared with non-violent patients with schizophrenia.3 Patients with a history of violence presented with more severe depressive symptoms. Within the group with a history of violence, the extent of aggression was positively related to the severity of the depressive symptoms.
The association between depression and violence has been frequently reported in persons with PTSD. In these individuals, the violence is often directed at intimate partners and close family members. For example, in veterans with PTSD, a major depressive episode was of the strongest risk factors for assaults on one’s spouse.4 Drug abuse/dependence was significantly higher in the violence group. In another study, the correlates of physical aggression against an intimate partner as well as general aggression were examined in male combat veterans with PTSD.5 A strong association for depression and aggression was found.
In dementia, as well, patients with depressive symptoms are more likely to exhibit physical aggression.6 And in bipolar disorder, increased violence is not limited to the manic phase but is also present in bipolar depression.7
Extensive literature exists on the relationship between depressive symptoms and violent behavior in general cohorts of children and adolescents. Blitstein and colleagues8 reported that depressive symptoms assessed at the outset of their study were an important predictor of violent behavior in seventh-graders. The association between violence and depressive symptoms is particularly common in children with conduct disorder.9
A new diagnosis of “mood dysregulation disorder” was added in DSM-5 for children who present with persistent irritability and frequent episodes of extreme behavioral dyscontrol, including violent behavior. Children with this pattern of symptoms are often described as “sad” or “unhappy” and frequently have unipolar depressive disorders later in life.
The reason for the association between violence and depression is not readily apparent, as there does not seem to be an obvious connection. It is possible that depression and violence coexist because of underlying factors that are responsible for both, such as alcohol/substance abuse or childhood trauma. In one study, depressed subjects with a history of alcoholism had higher lifetime aggression and impulsivity and were more likely to report a history of childhood abuse.10 A history of childhood trauma or abuse increases vulnerability to both depression and violent behavior.11,12
Dr. Krakowski is Senior Research Psychiatrist, Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY, and Associate Professor, Department of Psychiatry, New York University School of Medicine, New York. Dr. Nolan is Research Scientist, Clinical Trials Support, Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY, and Associate Professor, Department of Psychiatry, New York University School of Medicine, NY.
The authors report no conflict of interest concerning the subject matter of this article.
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