This web page was produced as an assignment for Genetics 564, an undergraduate course at UW‐Madison.
Overview of Aggression
The medical definition of aggression is "hostile, injurious, or destructive behavior or outlook especially when caused by frustration." [1]
Aggression can be
Examples of aggression include
Aggression can be
- directed at self, at others, at animals, at plants, or at properties
- impulsive or premeditated and goal-oriented
- for rehabilitation or without provocation
- physical or verbal
- direct or indirect
- overt, or covert [2]
Examples of aggression include
- hitting, kicking, biting, punching, or pinching
- tripping or pushing
- spitting or making rude hand gestures
- verbal or physical sexual harassment
- taking, discarding, or destroying one's belongings
- teasing, taunting, or name-calling
- embarrassing someone in public
- spreading rumors to defame someone
- making threats to cause harm
- socially excluding someone
Symptoms of Aggression
Aggression may accompany other symptoms that vary depending on the underlying disease, disorder or condition. Conditions that frequently affect behavior may also have other physical, psychological or cognitive symptoms. [3]
Physical symptoms include
Psychological or cognitive symptoms include
Physical symptoms include
- increase in heart rate and blood pressure
- changes in pupil size
- tension in muscles
- clenched jaw
- sweating
- seizures and tremors
- appetite changes and unintended weight changes
Psychological or cognitive symptoms include
- feeling frustrated, rejected and mistreated
- anxiety, irritability and agitation
- jealousy and inferiority
- confusion and disorientation
- memory problems or forgetfulness
- depression or flat mood
- difficulty with concentration or attention
- difficulty with language comprehension, writing or reading
- poor communication skills or social withdrawal
- hallucinations or delusions
- heightened arousal or acute awareness of the environment
- moodiness and personality fluctuations
- impaired judgment and decision making
- insomnia or sleep disturbances
Causes of Aggression
Although MAOA is the most compelling candidate for a gene of susceptibility for aggression, a continuous behavioral phenotype like aggression is likely a result from the action of a large number of genes which interact with each other— each exerting an effect that works with environmental factors through development and life.[4] The following are some explanations why aggression occurs.
Genetic and evolution
The primitive humans had to respond to threats such as animal attacks or invasion of their territory by fighting (display of aggression) or running away. As these 'fight or flight' responses were the key to survival, the associated traits must have been positively selected to be passed down.[5] It has been recognized that the trait of aggression are highly inheritable.
Environment and modeling
It has been shown that people who have experienced abusive childhood or traumatic early life events tend to be more aggressive. The explanation is that as a result of the maltreatment these individuals received, they will be on high alert for any threats towards them, thus more likely to interpret situations as threatening and more capable of reacting 'accordingly'. [5] Growing up in a home where aggression is a common expression of distress, children tend to mimic such behavior pattern until it is internalized.[2] Besides, in male-dominated environments, men still feel pressure from the society to 'man-up' via the portrayal of stereotypical masculine image of strength and dominance. Therefore, when stressful situations arise, some men resort to aggression which displays these traditional masculine images. [5]
Specific life events
Aggression might arise due to anger and frustration caused by some forms of threat or injustice [5], such as academic failure, financial insecurity, social marginalization, sexual harassment and loss of someone important.
Psychiatric or cognitive illnesses
Aggression may be a symptom of the following conditions or disorders: [6]
Brain injury
Aggression is elicited when anger-inciting stimuli are received, and the frontal lobes process this information. The frontal lobes are essential for functions such as impulse controls, behavioral inhibition, reasoning and decision making. Aggressive behavior may result if the frontal lobes are impaired or damaged, [2] which could be due to
Genetic and evolution
The primitive humans had to respond to threats such as animal attacks or invasion of their territory by fighting (display of aggression) or running away. As these 'fight or flight' responses were the key to survival, the associated traits must have been positively selected to be passed down.[5] It has been recognized that the trait of aggression are highly inheritable.
Environment and modeling
It has been shown that people who have experienced abusive childhood or traumatic early life events tend to be more aggressive. The explanation is that as a result of the maltreatment these individuals received, they will be on high alert for any threats towards them, thus more likely to interpret situations as threatening and more capable of reacting 'accordingly'. [5] Growing up in a home where aggression is a common expression of distress, children tend to mimic such behavior pattern until it is internalized.[2] Besides, in male-dominated environments, men still feel pressure from the society to 'man-up' via the portrayal of stereotypical masculine image of strength and dominance. Therefore, when stressful situations arise, some men resort to aggression which displays these traditional masculine images. [5]
Specific life events
Aggression might arise due to anger and frustration caused by some forms of threat or injustice [5], such as academic failure, financial insecurity, social marginalization, sexual harassment and loss of someone important.
Psychiatric or cognitive illnesses
Aggression may be a symptom of the following conditions or disorders: [6]
- attention-deficit hyperactivity disorder (ADHD)
- antisocial personality disorder (ASPD)
- conduct disorder (CD, precursor of ASPD)
- borderline personality disorder (characterized by unstable relationships)
- dementia, including Alzheimer’s disease and Huntington’s disease
- intermittent explosive disorder (characterized by extreme anger)
- oppositional defiant disorder (pattern of defiance and hostile behavior toward authority figures)
- acute delirium (sudden onset of mental status changes due to illness or toxicity)
- mania (elevated mood and energy levels that can occur in bipolar disorder)
- post-traumatic stress disorder
- schizophrenia
- autism
- substance abuse
Brain injury
Aggression is elicited when anger-inciting stimuli are received, and the frontal lobes process this information. The frontal lobes are essential for functions such as impulse controls, behavioral inhibition, reasoning and decision making. Aggressive behavior may result if the frontal lobes are impaired or damaged, [2] which could be due to
- stroke
- head injury
- brain tumor
- alcohol or drug intoxication
- hypoglycemia (low blood sugar)
- meningitis (infection or inflammation of the sac around the brain and spinal cord) [5]
Implications of Aggression
Leaving serious aggression untreated can result in serious complications and permanent damage, including physical, legal and psychological ramifications listed below: [2]
- difficulties interacting appropriately at work, in school, and in social environments
- troubled relationships with romantic partners and family members
- loss of a social network
- school suspension or expulsion
- unemployment or job loss
- drug and alcohol abuse
- increased risk of injury
- law violations and legal troubles
- self-harm or sucide
References:
- Aggression. Merriam-Webster Online. Retrieved Feb 2, 2014.
- Aggression Effects, Signs and Symptoms. Lakeland Behavioral Health System. Retrieved May 17, 2014.
- Aggression: Symptoms. Better Medicine from Healthgrades. Retrieved May 17, 2014.
- Tremblay, R. E., Hartup, W. W., & Archer, J. (2005). Developmental Origins of Aggression. New York: The Guilford Press.
- Causes of anger and aggression. First Psychology Scotland. Retrieved May 17, 2014.
- Aggression: Causes. Better Medicine from Healthgrades. Retrieved May 17, 2014.
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