Brain injury + hormonal links with offending behaviour

genes

xyy syndrome -theilgaard 1984

Warrior gene

twin studies

Twin studies - christiansen 1977

neurotransmitters and brain functions

BRAIN INJURY

• relationship between offending behaviour and brain injury caused by

Types of brain injury + def

1. Traumatic Brain Injury (TBI) - injury caused by external factors. e.g. accident

2. Acquired Brain Injury (ABI) - injury caused my internal factors. e.g. illness

Traumatic brain injury (tbi)

• damage to the brain from a hit

• can be seen as a chain of events

• 1st injury occurs seconds after the injury

• 2nd injury minutes and hours after

• 3rd injury can occur any time between the 1st and 2nd injuries and can cause further complications

Effects of brain injury

• Disinhibition

• Impulsiveness

• Obsessive behaviour

• irritability and aggression

• Egocentricity (self-centeredness)

Causes of Brain Injury ?

• Accidents - Leading cause to TBI

• Illness- stroke , infections cause cause ABI, often leading to significant neurological damage.

• Long-term Alcohol Use - chronic alcohol consumption can lead to structural brain changes

• Drug Abuse - prolonged use of certain drugs can cause neurodegeneration

Neurological Basis of Offending Behaviour

Limbic system

made up of hippocampus + amygdala+ hypothalamus + cingulate gyrus.

REGULATES emotions + aggression

Basal Gangila

Involved in motor control and behavioural regulation

Amygdala

• increased amygdala activity is associated with aggression

• Gospic et al ., discovered that amygdala activity increased in response to an aggressive game.

• taking drugs to lower this activity also lowered aggression

Neurophysiological impact of brain injury caused- cognitive impairments , emotional and behavioural changes

• Cognitive Impairments : Memory deficits, Attention problems, Executive dysfunction

• Emotional and Behavioural Changes ; Increased aggression, Impulsivity, Poor judgment

Brain injury from Long - term alcohol abuse

Neurotoxic Effects

Brain Regions Affected

• frontal lobes

• cerebellum

• hippocampus

Symptoms

• Memory deficits

• executive dysfunction

• emotional instability

brain injury from drug abuse + neurological consequences

• stimulants - caffeine , nicotine, cocaine

• Depressants- alcohol, cannabis

• Hallucinogens - Ketamine , salvi, PCP

Neurological consequences:

• cognitive deficits

• emotional instability

• brain damage

hormonal influences on behaviour

Testosterone

A key hormone associated with aggression, risk-taking behaviour and dominance.

Brain : influences areas such as amygdala and pre frontal cortex

Associated with aggression and risk - taking

testosterone and offending behaviour

• produced primarily in the testes in males + in ovaries and adrenal glands in females

• responsible for the development of male secondary sexual characteristics + influences behaviours e.g, aggression & competitiveness

Testosterone males ages 15-25 peak level

Peak Levels : Testosterone levels are highest during adolescence and early adulthood , a period often associated with increased aggression and risk-taking - which levels to violent behaviours

physiological effects on the male body

• promotes and increases muscle mass + strength

• mass density and strength of bone

• voice depth, growth of sexual organs , facial hair , change in facial shape , sexual drive

• changes develop in the womb and during puberty

Symptoms of low levels of testosterone in women

• weight gain

• hair loss

• insomnia

• fatigue

• depression

• low sex drive

• irritability

high testosterone in women

• acne

• excess body hair , especially in facial hair

• decreased breast size

• deepening of the voice

• increased muscle mass

• change sin mood

• irregular menstrual cycles

• low libido

Testosterone + aggression cause study + details

Albert et al., (1986) :

• studies the effect of testosterone on the aggression levels of male rats

• castration :

• castration with implantations of testosterone filled tubes

• castration with implantation of empty tubes -

• A sham castration with implantations of empty tubes ( rat underwent surgery but testifies not removed ) - control

Findings :

Aggression: Rats with lowered testosterone (from castration or empty tubes) showed a major drop in aggression

-reducing testosterone levels reduced levels of aggression + the social status of male rats.

Those that had the operations with decreased levels

of testosterone - had a decrease in aggressiveness

- Those that had the operation that kept testosterone levels intact didn’t have a significant change in aggression levels.