Aggression and violence remain a central clinical issue worldwide. Aggression has many meanings, and the term occurs in a variety of contexts. In this article, violence and aggression will be considered together. Aggression is any behavior, including verbal events, which involves attacking another person, animal, or object with the intent of harming the target. Similarly, violence is intentionally using physical force to hurt, damage, or kill someone or something.
Biological, psychological, and socioeconomic influences must be considered when discussing the etiology of aggression. Biological causes include genetics, medical and psychiatric diseases, neurotransmitters, hormones, abused substances, and medications. Psychological causes include numerous Diagnostic and Statistical Manual of Mental Disorders (DSM–5) diagnoses. These include Bipolar Affective Disorder, Schizophrenia, Major Depression, General Anxiety Disorder, and Antisocial personality.Alniak, 2015; Socioeconomic causes include interpersonal, social, group, neighborhood, economic, and cultural conditions that can create the potential for or actual violence. Importantly, these factors often act concomitantly.
Violence is ubiquitous. United States statistics, collected by the Federal Bureau of Investigation and reported in the 2013 Unified Crime Report, noted that there were an estimated 1,163,146 violent crimes that occurred nationwide. Also, information collected regarding types of weapons in violent crime showed that firearms were used in 69% of murders, 40% of robberies, and 21.6% of aggravated assaults. Furthermore, a woman was beaten every 9 seconds. On average, nearly 20 people per minute were physically abused by an intimate partner. During one year, this equates to more than 10 million women and men. Also, one in five women and one in 71 men, in the United States, have been raped in their lifetime. Nearly half of female (46.7%) and male (44.9%) victims of rape knew their attackers. Finally, 1 in 15 children are exposed to intimate partner violence each year, and 90% of these children are eyewitnesses to this violence.
Although the definition of aggression is simple and straightforward, its origins remain complex and frequently depend upon other, often contradictory, factors. In this exploration, there will be a review of the biological, psychological, and social causes of violence. In exploring the biological basis, there is an analysis of the genetics, brain structures, medical diseases, neurotransmitters, hormones, abused substances, and medications that contribute to aggression. In the psychological assessment, there is an investigation of the DSM–5 diagnoses linked to aggression. Finally, there is an investigation into the social and environmental roots of violence.
Although any individual may become aggressive for a variety of reasons, there is a number of specific DSM-5 diagnoses which have violent behavior as one of their features. These include bipolar affective disorder, schizophrenia, the dementia group, post-traumatic stress disorder (PTSD), and acute stress disorder. Also, several of the disorders associated with childhood and adolescence, intellectual deficiencies, some personality disorders, and intermittent explosive disorder are associated with violent behavior. As noted earlier, aggression can result from a combination of several conditions. For example, certain persons with PTSD may become violent after consuming alcohol.
It has known patients with the bipolar affective disorder to become excessively agitated and aggressive, especially during the manic phase. Grandiose delusions often not only dramatically inflate their self-view but also make them demanding of others and combative to those not acknowledging their perceived greatness. Patients with schizophrenia can be aggressive when responding to command hallucinations ordering them to harm others. Patients with a wide range of dementias, such as Alzheimer disease, not only have memory deficiencies but also lose their executive functions. These executive functions provide good judgment and inhibit unacceptable impulses. This can account for some of the violence seen in long-term care facilities and in places where patients with traumatic brain injuries are treated.
An overwhelming stress can make certain individuals aggressive. It is their way of coping. Patients with PTSD struggle with a host of symptoms which can promote potential aggression. These symptoms include hypervigilance, flashbacks, and nightmares, and can lead to aggression. Several childhood diagnoses including conduct disorder and attention-deficit/hyperactivity disorder (ADHD) can result in aggressive behavior, as can disorders along the autism spectrum, because of communication difficulties, impulsiveness, low tolerance, and frustration. ( Saylor, 2016)
Persons with intellectual deficiencies, when confronting difficult tasks and situation, may resort to violence as a coping mechanism. ( Davies, 2016) Certain personality disorders, such as antisocial personality and borderline personality, can cause individuals to exhibit belligerence. Individuals who are antisocial lack an empathic view and have an egocentric center of gravity which can promote aggression. A person with a borderline personality who is overwhelmed and has boundary issues can become aggressive. Finally, aggression is at the core of persons with the intermittent explosive disorder.
Aside from these formal diagnoses, when people are afraid, overwhelmed, feel threatened, or feel out of control, perplexed, disorientated, or frustrated, they often respond aggressively.
Sociocultural Economic Factors
The environment can contribute to aggression on many levels: interpersonal, social, group, neighborhood, economic, and cultural conditions can create the potential for or actual violence.
Interpersonal: Interpersonal aggression occurs in a variety of settings. One of the most noted is domestic violence. ( Foshee, 2016) An intimate relationship can promote violence through jealousy, fear of abandonment, domination, and control issues. (Cunha, 2016) This involves spousal or companion abuse. ( Lehtonen, 2016) its extreme form, intimate aggression can ultimately result in homicide or suicide.( Murphy, 2016) Other forms of domestic violence include child abuse and senior abuse. Relationships generate intense emotions. Geriatric units and long term care facilities produce intense interpersonal feelings.  ( Lanza, 2016) Also violence can erupt on psychiatric in-patient units.  (Renwick, 2016) Prisons and jails represent places where violence erupts. (Heynen, 2016) Bullying in any setting is both aggressive in and of itself and can lead to violence.  (Maniglio, 2016; Mudrak, 2015)
Social: In social situations, frustrations can accumulate over time. This is known as an incubation period. In sociology, there is the term "relative deprivation." In this phenomenon, an oppressed group is granted some gains. They have not achieved all they wanted, but there have been some advances. However, instead of the people being grateful, they realize that they have not received all the items of which they have been deprived and act aggressively. For some, they accumulate enough things that annoy them, and they reach a "tipping" point, where the aggression frequently erupts in violence.
Group: Group experiences also can cause aggression. When many people assemble in one place, there can be a growing aggression.
The treatment of aggression and violence must be based on their causes. Diagnosis leads to treatment. If it a mental disorder the responsible contributor then the specific disorder must be addressed.  (Gurnani, 2016 )
The diagnosis and management of aggression is with a multidisciplinary team that includes a mental health nurse, psychiatrist, an emergency department physician, psychologist, and a social worker. The treatment depends on the cause but in many cases, it may be psychiatric. Both medications and psychotherapy have been used to treat this disorder but relapses are common. Many of these patients eventually run into legal problems because of their behavior.
|||Substance use is a risk factor for violent behavior in male patients with bipolar disorder., Alnıak İ,Erkıran M,Mutlu E,, Journal of affective disorders, 2015 Dec 30 [PubMed PMID: 26771949]|
|||Aggressive behavior in humans: Genes and pathways identified through association studies., Fernàndez-Castillo N,Cormand B,, American journal of medical genetics. Part B, Neuropsychiatric genetics : the official publication of the International Society of Psychiatric Genetics, 2016 Jan 15 [PubMed PMID: 26773414]|
|||The role of monoamine oxidase A in aggression: Current translational developments and future challenges., Godar SC,Fite PJ,McFarlin KM,Bortolato M,, Progress in neuro-psychopharmacology & biological psychiatry, 2016 Jan 9 [PubMed PMID: 26776902]|
|||High trait aggression in men is associated with low 5-HT levels, as indexed by 5-HT4 receptor binding., da Cunha-Bang S,Mc Mahon B,MacDonald Fisher P,Jensen PS,Svarer C,Moos Knudsen G,, Social cognitive and affective neuroscience, 2016 Jan 15 [PubMed PMID: 26772668]|
|||High prevalence of physical and sexual aggression to caregivers in advanced Parkinson's disease. Experience in the Palliative Care Program., Bruno V,Mancini D,Ghoche R,Arshinoff R,Miyasaki JM,, Parkinsonism & related disorders, 2016 Jan 11 [PubMed PMID: 26786755]|
|||Turner D,Basdekis-Jozsa R,Briken P, Prescription of testosterone-lowering medications for sex offender treatment in German forensic-psychiatric institutions. The journal of sexual medicine. 2013 Feb [PubMed PMID: 23088739]|
|||Ganson KT,Cadet TJ, Exploring Anabolic-Androgenic Steroid Use and Teen Dating Violence Among Adolescent Males. Substance use & misuse. 2018 Dec 21 [PubMed PMID: 30572768]|
|||Thiessen MS,Walsh Z,Bird BM,Lafrance A, Psychedelic use and intimate partner violence: The role of emotion regulation. Journal of psychopharmacology (Oxford, England). 2018 Jul [PubMed PMID: 29807492]|
|||Kirwan M,Lanni DJ,Warnke A,Pickett SM,Parkhill MR, Emotion Regulation Moderates the Relationship Between Alcohol Consumption and the Perpetration of Sexual Aggression. Violence against women. 2018 Oct 25 [PubMed PMID: 30360699]|
|||Khemiri L,Jokinen J,Runeson B,Jayaram-Lindström N, Suicide Risk Associated with Experience of Violence and Impulsivity in Alcohol Dependent Patients. Scientific reports. 2016 Jan 19 [PubMed PMID: 26784730]|
|||Maniglio R, Bullying and Other Forms of Peer Victimization in Adolescence and Alcohol Use. Trauma, violence & abuse. 2017 Oct [PubMed PMID: 26888020]|
|||[PubMed PMID: 26821942]|
|||[PubMed PMID: 26744906]|
|||[PubMed PMID: 26746242]|
|||[PubMed PMID: 26822376]|
|||[PubMed PMID: 26792425]|
|||[PubMed PMID: 26818933]|
|||[PubMed PMID: 26892149]|
|||[PubMed PMID: 26873150]|
|||[PubMed PMID: 26799905]|
|||[PubMed PMID: 26881859]|
|||Kendrick JG,Goldman RD,Carr RR, Pharmacologic Management of Agitation and Aggression in a Pediatric Emergency Department - A Retrospective Cohort Study. The journal of pediatric pharmacology and therapeutics : JPPT : the official journal of PPAG. 2018 Nov-Dec; [PubMed PMID: 30697130]|
|||Sommovigo V,Setti I,Argentero P,O'Shea D, The impact of customer incivility and verbal aggression on service providers: A systematic review. Work (Reading, Mass.). 2019; [PubMed PMID: 30689593]|