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The question

I may have partied a little too hard on the Labour Day weekend. I'm not normally a heavy drinker but I'm pretty sure I overdid it on Sunday night because I don't remember much of it. Does drinking to the point of blacking out like this pose any long-term health or memory problems?

The answer

Blackouts happen when alcohol or some other substance interferes with our ability to form long-term memories. Blacking out is different than passing out as during a blackout, most people are fully conscious and may seem alert, but are later unable to recall any details of events or actions that happened while they were drinking.

So while the impact of blackouts on your long-term health and memory is a valid concern, it is also important to realize there are consequences that can arise from the potentially dangerous behaviours that people engage in during those blackout periods.

Blackouts are thought to occur because of drinking too much too quickly. They seem to have a strong link to the rate at which the alcohol concentration in the blood rises. For some, blackouts happen only after consuming large volumes of alcohol. While for others, it can happen after one or two drinks. This indicates (as research in this area has shown) that some people may be more susceptible to blacking out than others.

We all know alcohol can affect our co-ordination, vision, speech, reaction times and memory. And while most of these changes to the body reverse after alcohol is metabolized, there is potential for lasting effects on health and memory with regular, long-term use.

Again, this varies from person to person. So while it sounds like this is an irregular occurrence for you, it is hard to judge what the long-term effects could be as there are many other variables at play and everyone is unique.  The bottom line is however, alcohol clearly has an effect on the brain.  Blackouts – especially if they are happening frequently – are a sign that something more serious is happening and may certainly impact your memory and long term brain function.

While blackouts seem to have a connection to heavy drinking, the amount alone is not enough to cause temporary memory loss.

Other factors that can contribute to how a person's body reacts to alcohol are:

  • How much alcohol is consumed and how often
  • How long you’ve been drinking
  • Genetics
  • General overall health

Specifically, memory loss will depend on these factors, so this is why the extent of the blackout can vary from being "fragmentary" – or partial loss recollection of events – to "complete," where there is no recollection at all of any events or actions that happen while intoxicated.

A recent study in the journal Injury Prevention noted that college students with a history of blackouts were more likely to get injured when drunk in the future. This study proved that perhaps the bigger health concern of blackouts is the potential for injurious actions to happen while under the influence of alcohol. When people blackout, inhibitions lessen and risky behaviours, such as driving drunk, getting into arguments or physical fights, engaging in criminal activity or having unprotected sex, tend to increase.

Reduce your risk of blacking out by abstaining or drinking in moderation. If you are drinking, avoid rapid consumption and try not to drink on an empty stomach.

Most importantly, listen to your body. You don't have to be an alcoholic to blackout. But if you are experiencing blackouts, you should remember they are an indication of rapid and excessive drinking and caution needs to be taken. Seek a health-care provider if you need someone who can review your concerns and assess your individual risks in detail.

If you have a family history of alcoholism, take extra caution as this may indicate that you have a genetic susceptibility to the effects of alcohol and dependence.

Send family doctor Sheila Wijayasingheyour questions at She will answer select questions, which could appear in The Globe and Mail and/or on The Globe and Mail web site. Your name will not be published if your question is chosen.

The content provided in The Globe and Mail's Ask a Health Expert centre is for information purposes only and is neither intended to be relied upon nor to be a substitute for professional medical advice, diagnosis or treatment.