Blackout Or Partial Amnesia After Drinking Alcohol

Blackout syndrome is a phenomenon that occurs due to acute intoxication derived from alcohol consumption. It is a kind of amnesia that affects any memory that includes episodes that have occurred under the influence of alcohol.

Thus, blackout is characterized by memory impairment during alcohol intoxication. Under this syndrome, affected people can behave in certain characteristic ways. One is known as blocking, which causes people to drive long distances without being fully aware of it or to have seemingly normal conversations at parties that they may later not remember.

Affected subjects often believe they are awake in strange places without remembering how they got there. Thus, some people under the influence of this syndrome are capable of even committing criminal acts such as murder (2).

Types of blackout

A blackout can be complete (in block) or partial (fragmentary or attenuated). Thus, when a person is affected by a complete blackout, they have total amnesia with respect to certain significant episodes that would otherwise be memorable. What most characterizes this type of blackout is that the memory loss is permanent and cannot be recovered under any circumstances.

However, it seems that fragmentary blackouts occur more frequently (4, 5). In this type of alcohol-induced amnesia, you are more likely to remember what happened or part of it.

In these cases, the patient may believe that he has nothing to remember, that these forgotten events simply do not exist. Thus, meta-memory deficit is a problem in partial blackout research .


This syndrome is especially common in people who have a high volume and frequency of alcohol consumption.

In fact, this factor is the most related to the causes of blackout . Thus, today it is known that anyone who drinks too much and too fast can experience a blackout .

Risk factor’s

Although a high concentration of alcohol in the blood is required to induce a blackout, many of these people who drink alcohol recall drinking much more and not having this type of amnesia (6).

Thus, it seems that the main risk factors for blackout are:

  • Drinking alcohol (usually quickly).
  • Drink on an empty stomach.
  • And drink liquor or alcohol other than beer.

However, it seems that not all those who drink quickly and excessively have this type of amnesia episode. There are people who, for whatever reason, are more vulnerable to alcohol-induced memory impairment (6, 7).

Pathophysiology of the blackout

A blackout is the result of alcohol-induced disruption of memory formation. Memory formation involves the following processes (8):

  • Coding, initial registration and interpretation of stimuli.
  • Storage, consolidation and maintenance of coded stimuli.
  • Recovery. That is, the search and retrieval of stored stimuli.

Alcohol has its greatest effects on the first memory process, encoding. The effect of alcohol on coding can disrupt the processing of the context for the formation of episodic memory.

Episodic memory takes care of the context of memories. If the episode is encoded with a faulty context, as can happen in blackout, then the retrieval of memories related to episodic memory can be particularly difficult (9, 10) or even impossible, in the case of total blackout.

The good thing about partial blackout is that, in them, reminding a subject of the events that occurred during the blackout often brings back some forgotten memories. These details can be beneficial in rebuilding memory that was not well encoded.

Therapeutic implications in alcohol-induced amnesia

Today it seems clear that blackouts do not only occur in those who abuse alcohol. However, blackout is an indication of excessive consumption of it. In fact, a large majority of alcoholics experience blackouts during the early phase of addiction (11).

In addition, the blackouts chronic can be a clear sign of alcoholism. It has been found in a study that college students with this syndrome were frightened by the amnesia they had. Therefore, his alcohol consumption decreased.

The fact is that, if alcohol consumption behavior is not adequately modified after the occurrence of this syndrome, this can lead to a chronic addiction to alcohol. Thus, learning about this situation can be key in those affected by alcohol-induced amnesia.