Why does alcohol change someone's behaviour?
Alcohol interferes with parts of the brain involved in judgement, decision-making and impulse control. Someone may become louder, more emotional, reckless, argumentative or aggressive, or do things they would normally stop themselves doing.
These changes can begin before the person looks obviously drunk.
Why does alcohol affect judgement and coordination?
Alcohol disrupts the brain systems involved in clear thinking, balance, speech, reaction time and coordinated movement.
As the amount of alcohol in the bloodstream rises, decisions become less reliable and movements can become slower, less accurate and harder to control.
Why can alcohol cause memory loss?
Alcohol can interfere with the hippocampus, a part of the brain involved in forming new memories. If enough alcohol is consumed, the brain may stop storing parts of what is happening as long-term memories.
The person can therefore have gaps in their memory the next day even though they were awake at the time.
What is an alcohol blackout?
A blackout is a period during which someone is conscious but later cannot remember some or all of what happened. They may have been talking, walking, arguing, eating or doing other things while their brain was failing to form new memories normally.
A blackout is not the same as passing out. Passing out means losing consciousness.
Why can someone drink a lot and not look drunk?
With repeated heavy drinking, the brain can adapt to the presence of alcohol. The person may need more alcohol to produce effects they once felt after drinking less. This is called tolerance.
Tolerance can make someone appear less affected by a large amount of alcohol. It does not mean the alcohol is causing less harm or that they are safe to drive, work or make important decisions.
How does alcohol dependence develop?
Repeated heavy drinking can change brain systems involved in reward, stress, habits, decision-making and impulse control. Drinking can gradually become harder to control.
The reason for drinking can also change. Someone may initially drink because they enjoy its effects, but later drink partly to avoid the physical or emotional discomfort that appears when the alcohol wears off.
What happens to the brain when alcohol wears off?
A brain that has adapted to regular heavy drinking can become overactive when alcohol is suddenly reduced or removed. This is part of alcohol withdrawal.
Symptoms can include anxiety, irritability, shaking, sweating, disturbed sleep, nausea and a racing heart. Severe withdrawal can cause seizures, hallucinations or severe confusion.
Why can another drink stop the shaking or make them feel better?
If someone is physically dependent on alcohol, withdrawal symptoms can begin as the amount of alcohol in their body falls. Drinking again reintroduces alcohol and can temporarily reduce those symptoms.
That temporary improvement can make it look as though alcohol is helping them. In reality, needing alcohol to relieve withdrawal is a sign that dependence may have developed.
Can alcohol permanently damage the brain?
Long-term heavy drinking can alter the structure and function of the brain and affect memory, attention, judgement, decision-making and other mental functions.
Some alcohol-related changes can improve after drinking stops, sometimes over months. The amount of recovery varies, and some damage can persist.
Can suddenly stopping alcohol be dangerous?
Yes. Severe alcohol withdrawal can be life-threatening. Seizures, hallucinations and severe confusion are medical emergencies.
Someone who drinks heavily and may be physically dependent should get medical advice before suddenly stopping or sharply reducing their alcohol intake.