Why people get aggressive after drinking

Researchers have used magnetic resonance imaging (MRI) scans that measure blood flow in the brain to understand why people become aggressive and violent after drinking alcohol. After only two drinks, the researchers noted changes in the working of the prefrontal cortex of the brain, the part involved in tempering a person's levels of aggression. The study was led by Thomas Denson of the University of New South Wales in Australia in the journal Cognitive, Affective, & Behavioral Neuroscience.

According to most theories, alcohol-related aggression is caused by changes in the prefrontal cortex. However, there is a lack of substantial neuroimaging evidence to substantiate these ideas. In this study, Denson and his team recruited fifty healthy young men. The participants were either given two drinks containing vodka, or placebo drinks without any alcohol. While lying in an MRI scanner, the participants then had to compete in a task which has regularly been used over the past 50 years to observe levels of aggression in response to provocation.

The functional magnetic resonance imaging allowed the researchers to see which areas of the brain were triggered when the task was performed. They could also compare the difference in scans between participants who had consumed alcohol and those who hadn't. Being provoked was found to have no influence on participants' neural responses. However, when behaving aggressively, there was a dip in activity in the prefrontal cortex of the brains of those who had consumed alcoholic drinks. This dampening effect was also seen in the areas of the brain that are involved reward. Also, heightened activity was noted in the hippocampus, the part of the brain associated with people's memory.

Although there was an overall dampening effect of alcohol on the prefrontal cortex, even at a low dose of alcohol there is a significant positive relationship between dorsomedial and dorsolateral prefrontal cortex activity and alcohol-related aggression. These regions may support different behaviors, such as peace versus aggression, depending on whether a person is sober or intoxicated.

The results are largely consistent with a growing body of research about the neural basis of aggression, and how it is triggered by changes in the way that the prefrontal cortex, the limbic system and reward-related regions of the brain function. The results of the current study are also consistent with several psychological theories of alcohol-related aggression.
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Women have more active brains than men

Researchers used single photon emission computed tomography SPECT to spot the differences between the brains of men and women. Using functional neuroimaging tools like SPECT, are essential for brain treatments.

The brains of women in the study were significantly more active in many more areas of the brain than men, especially in the prefrontal cortex, involved with focus and impulse control, and the limbic or emotional areas of the brain, involved with mood and anxiety.

The visual and coordination centers of the brain were more active in men. SPECT can measure blood perfusion in the brain. Images acquired from subjects at rest or while performing various cognitive tasks will show different blood flow in specific brain regions.

Researchers examined healthy participants and patients with different psychiatric conditions such as brain trauma, bipolar disorders, mood disorders, psychotic disorders, and attention deficit hyperactivity disorder ADHD.

A total of 128 brain regions were analyzed while performing a concentration task. Understanding these differences is important because brain disorders affect men and women in different ways.

Women have significantly higher rate of depression, which is a risk factor for Alzheimer's disease and anxiety disorders, while men have higher rates of  attention deficit hyperactivity disorder ADHD and incarceration.

Their is an increased prefrontal cortex blood flow in women compared to men, this may be the reason why women tend to exhibit greater strengths in the areas of empathy, intuition, collaboration and self-control.

Researchers also found increased blood flow in limbic areas of the brains of women, which may be the reason why women are more vulnerable to anxiety, depression, insomnia, and eating disorders.
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