WE’VE all been there. It’s the morning after a big night out and you’re battling to remember anything you did or said.

So what’s happening inside your brain after having too much to drink?

Preventive health expert Dr Ross Walker says alcohol degenerates cells rapidly and mainly affects the liver, heart and brain.

“If you did a CAT scan of an alcoholic’s brain at age 40 and compared that to the brain of a normal 40-year-old, there would be much less tissue in the brain,” he told news.com.au

“It rots the brain, basically. Chronic consumption of alcohol has been linked to alzheimers.”

Alcohol can have a “dramatic impact” on memory, according to a 2004 US National Institute on Alcohol Abuse and Alcoholism research paper. The paper reviewed decades of information on alcohol and brain health.

“Alcohol primarily interferes with the ability to form new long-term memories, leaving intact previously established long-term memories and the ability to keep new information active in memory for brief periods,” the paper states.

“As the amount of alcohol consumed increases, so does the magnitude of the memory impairments ... If recreational drugs were tools, alcohol would be a sledgehammer.”

Dr Walker says alcohol-induced memory loss is caused by a disruption of the brain’s hippocampus, which is housed in the centre of the brain. “It’s a very important part of the brain for short-term memory,” he said.

There are two main memory and neurological disorders caused by heavy drinking — Korsakoff’s psychosis and Wernicke’s encephalopathy.

In the brain of a Korsakoff’s sufferer, the hippocampus is “picked off” by alcohol.

“These people just completely lose their short term memory. They don’t know what they did or said a minute or so beforehand,” Dr Walker said.

Wernicke’s encephalopathy is basically severe vitamin B defiency, particularly B1.

“They have cranium nerve palsy. They might get double vision problems in the face. The treatment for them is thiamine, which is Vitamin B1.”

Even in casual drinkers, the hippocampus is still affected by the toxins in alcohol. This is what causes you to forget — either temporarily or permanently — certain memories.

The 2004 research paper says while you might be able to recall long term memories etched into your brain — and repeat new stuff you’ve literally just learnt — in just a few minutes you’ll have forgotten what someone just told you.

“Intoxicated subjects are typically able to repeat new information immediately after its presentation and often can keep it active in short-term storage for up to a few minutes if they are not distracted, though this is not always the case,” the paper states.

“Similarly, subjects normally are capable of retrieving information placed in long-term storage prior to acute intoxication.

“In contrast, alcohol impairs the ability to store information across delays longer than a few seconds, if subjects are distracted between the time they are given the new information and the time they are tested.”

Read the full paper here.