How the Brain Learns Addiction
A new study has found how the brain learns addiction.
Researchers from the Perelman School of Medicine at the University of Pennsylvania (Penn), United States, found that alcohol directly affects the brain’s learning and memory system through a test on mice. Consuming alcohol makes people learn to continue using alcohol.
This learning can make people want to use more alcohol when they’re in certain environments or with groups of people.
Earlier this year (2019), researchers from Rutgers University found that binge alcohol use can trigger genetic changes that make people crave alcohol even more.
The new study found:
- When alcohol is consumed, it goes to the liver, where it is processed into the by-product acetate.
- Acetate then travels to the brain, where it turns certain genes on and off in a cell by attaching to histones, the proteins that package DNA in a cell’s nucleus.
- The enzyme responsible for depositing acetate into cells, called ACSS2, activates key memory genes important for learning.
To test this, researchers exposed mice to two differently patterned chambers – one with alcohol and one without.
- After a “learning period”, the mice were allowed to roam freely between the two. They preferred the chamber that was paired with alcohol.
- But after lowering the levels of ACSS2 in the mice’s brains, the researchers found that they spent an equal amount of time in both chambers.
- Researchers also found that when a pregnant mouse consumed alcohol, acetate was delivered through the placenta and into the foetus’ developing brain.
The research is consistent with the idea that addiction is a learned process and the first study showing that alcohol consumption affects how genes are expressed in the brain.
Brain imaging shows link between alcohol dependence and self-control
In another study researchers have used brain imaging to further assess the links between self-control and alcohol dependence.
The study took place in Germany and involved 62 patients who had been hospitalized with alcohol dependence and had recently detoxified, as well as 62 healthy people. The research included surveys on lifetime alcohol intake and to measure traits of impulsivity and sensation seeking and MRI scans.
The brain scans showed that,
- Compared with the healthy participants, patients with alcohol dependence were deficient in grey matter in frontal areas of the brain that are known to be involved in self control.
- Patients also scored higher than the controls on measures of impulsivity, although there were no differences between the two groups in sensation seeking.
- The lower-intake patients scored more highly than high-intake patients on measures of sensation-seeking behavior.
- Among the lower-intake subgroup, the volume of grey matter in one region of interest correlated with how highly patients scored for thrill and adventure seeking behavior.
The findings highlight that there are differences among people with alcohol dependence and individualized treatment strategies are needed.