James G. Wigmore, Forensic Toxicologist, Speaker, Author

lcohol-induced blackouts are often confused with loss of consciousness or

automatism.  Ablackout, however, is just a total loss of memory (amnesia) that can occur during heavy drinking and rapid consumption of alcohol (WOA60301-60305).  This memory loss is anterograde in that there is memory loss after a high BAC is obtained and onward, while the person is intoxicated.    This is in contrast to retrograde amnesia which can occur when there is a blow to the head and the person cannot remember their past, such as their name.

Alcohol is typically not a drug that is associated with automatism (for a more detailed discussion of automatismclick here) and the behavior of the individual suffering from a blackout does not appear to change to an outside observer.  As one researcher stated:

“What we found was that remote memory was intact but that people had trouble with short term memory, which meant that during a blackout, a person would be able to recite the Ten Commandments and know the consequences of robbing a bank.  It was simply that he would not remember these things for 30 minutes later or the next day.  He knew right from wrong at the time of the act and this appears to be the critical fact where the law is concerned.” (WOA60302)

A less confusing and better name for “blackout” would perhaps be “blankout”.

Some of the characteristics of an alcohol induced blackout are:

  • The consumption of liquor, or of both liquor and beer, is much more frequently associated with blackouts than the consumption of beer alone.

  • Gulping drinks especially on an empty stomach increases the risk of a blackout.

  • The mean BAC at which the blackout occurs is approximately 0.230 g/100mL.

  • On average 10 to 14 drinks are consumed prior to a blackout.

  • Most persons with blackouts tend to be alcohol dependent at the time.

  • Most persons with blackouts rely on others to provide details of what occurred during the blackout and often have a sense of dread or apprehension about what occurred.

The next blog in this series will apply these principles and show the potentially serious legal consequences that can occur with a blackout in a case report of an alleged Drug Facilitated Sexual Assault (DFSA).