Alcohol-Induced Amnesia: Signs, Risk Factors and Treatment Options

Alcohol use in excessive amounts in the short-term can cause temporary amnesia, referred to as a blackout. Chronic use can impair the ability to retrieve and form memories.

The adverse effects of prolonged use of excessive amounts of alcohol are well-documented and include liver damage and cardiovascular conditions. Besides these effects, chronic alcohol use can also directly or indirectly cause brain damage and result in alcohol-induced dementia. Alcohol-induced dementia involves impaired cognitive functioning and may also be referred to as alcohol amnestic disorder. This is due to the presence of amnesia, along with other cognitive deficits.

The impairment of memory and learning caused due to chronic alcohol intake may not be reversible. Similarly, acute alcohol intoxication also results in an impaired ability to form new memories, referred to as alcohol-induced blackouts. However, unlike chronic alcohol intake, anterograde amnesia (inability to form new memories) caused by alcohol intoxication is only temporary.

Signs of Alcohol-Induced Amnesia

Even small amounts of alcohol can produce memory impairments. The degree of impairment increases along with the level of alcohol intake. Despite their inability to form new memories, individuals are often able to participate in social activities or engage in complex activities like driving a car. Driving while intoxicated is illegal and not recommended.

Some of the signs of an alcohol-induced blackout may include:

• Inability to focus and losing track of conversations
• Inability to remember recent events
• Difficulty understanding normal speech

Alcohol-induced amnesia occurs due to high levels of alcohol in the body and is often accompanied by:

• Slurred speech,
• Blurred vision,
• Impaired motor coordination, and
• Impaired decision making.

An alcohol-induced blackout, in combination with the other symptoms of alcohol intoxication, can result in risky and reckless behaviors.

Symptoms of Amnesia

Unlike the amnesia induced by acute alcohol intoxication, the effects of chronic use of excessive amounts of alcohol may be persistent. Some of the symptoms of amnesia induced by chronic alcohol intake may include:

• Impaired ability to recall previously acquired information (retrograde amnesia)
• Impaired ability to form new memories (anterograde amnesia)
• Impaired visuospatial abilities – difficulty recognizing or identifying objects
• Impaired motor coordination and difficulty maintaining balance
• Deficits in executive functioning involving complex cognitive processes like planning, thinking, and decision-making

Alcohol-Induced Blackouts

The impaired ability to form new memories (temporary anterograde amnesia) is referred to as an alcohol-induced blackout.

Memory normally functions as initially storing information acquired from the environment in the short-term memory. It is then transferred to long-term memory upon the rehearsal of this information.

Short-term memory has a limited storage capacity. Thus, newly acquired information persists in short-term memory only for a few minutes (five to 30 minutes). Long-term memory has a much greater capacity. Information may be stored there for anywhere between a few days to years.

Rapid intake of high levels of alcohol disrupts the transfer of information from short-term memory to long-term memory. During a blackout, individuals are able to retain new information in their short-term memory for a few minutes in the absence of distractions. This enables individuals to engage in social activities, have conversations, and even drive a vehicle. Similarly, the memories formed before and after the blackout also remain intact.

The memory loss during a blackout impacts the ability to store long-term memories. Therefore, memories may be partial or complete, with partial memory loss being more common. In the case of partial or fragmentary blackouts, individuals are able to remember some information regarding the events during the blackout episode upon being prompted with information. When a complete blackout occurs, there is no long-term memory stored, and therefore the entire evening could potentially be forgotten.

Wernicke-Korsakoff Syndrome

Besides causing amnesia due to intoxication, chronic use of alcohol can also cause cognitive deficits that are often irreversible. Chronic alcohol use can also indirectly cause brain damage by causing thiamine deficiency.

Chronic thiamine deficiency can lead to Wernicke-Korsakoff syndrome that is characterized by symptoms such as:

• Double vision
• Paralysis of certain eye muscles
• Inability to walk or maintain footing
• Rapid heartbeat
• Loss of consciousness

Thiamine or vitamin B1 is essential for the normal functioning of all tissues, including the brain. Thiamine is not synthesized by the body and hence, must be acquired through diet. Alcohol directly interferes with the absorption of thiamine from the gastrointestinal tract and its utilization by various tissues in the body.

Prolonged alcohol intake is also associated with a poor diet and can result in nutritional thiamine deficiency. Thiamine plays an important role in a wide variety of critical biochemical reactions in the brain, including in glucose metabolism and the synthesis of neurotransmitters. Thiamine also plays a vital role in protecting tissues from oxidative stress.

Thiamine deficiency over a period of time can lead to neuronal damage and dysfunction of the blood-brain barrier. Certain brain regions are more sensitive to these effects of thiamine deficiency and result in specific symptoms described by Wernicke’s encephalopathy.

Wernicke’s Encephalopathy

Wernicke’s encephalopathy is an acute and life-threatening condition that can be treated by thiamine administration. Wernicke’s encephalopathy is characterized by symptoms that include:

• Paralysis of nerves that control eye movements Impaired motor coordination
• Changes in mental status, such as confusion, apathy, and reduced speech

Korsakoff’s Psychosis

If untreated, Wernicke’s encephalopathy may progress to Korsakoff’s psychosis, which is a chronic and debilitating condition. Korsakoff’s psychosis is characterized by difficulty in retrieving existing memories (retrograde amnesia) accompanied by an impaired ability to form new memories (anterograde amnesia).

Other symptoms of Korsakoff’s psychosis may include:

• Hallucinations
• Agitation
• Confabulation (unintentionally making up stories)

In almost 80% of the case of Wernicke’s encephalopathy, the condition progresses to cause Korsakoff’s psychosis. Due to their frequent co-occurrence, these conditions combined are referred to as Wernicke-Korsakoff syndrome. Most individuals with Wernicke-Korsakoff syndrome will show at least some degree of persistent deficits in learning and memory.

Prevention of Alcohol-Induced Amnesia

Acute and chronic intake of alcohol in excessive amounts is associated with adverse effects on the physical and mental health of the individual. Hence, it is advisable to limit the intake of alcohol to a drink or two and avoid alcohol abuse.  Guidelines from the Center for Disease Control recommend limiting alcohol intake to 1 drink for women and 2 for men.

Restricting alcohol intake to low levels can even have protective effects on cognitive function, whereas moderate-to-heavy alcohol use is associated with negative outcomes. Even occasional intoxication with alcohol may lead to a blackout and requires social drinkers to be vigilant about such negative consequences.

Many individuals consume excessive amounts of alcohol without suffering such an episode of amnesia. Other factors, such as the rapid intake of large amounts of alcohol and drinking on an empty stomach, contribute to the occurrence of memory blackouts. Therefore, besides restricting the consumption of alcoholic beverages, it is advisable to pace the use of alcohol. Caution should be exercised in the case of drinks with high alcohol content. Staying hydrated and having a meal before drinking can also help to prevent such an episode of an alcohol-induced blackout.

If you or a loved one struggle with alcohol abuse or addiction, contact The Recovery Village Palm Beach at Baptist Health to speak with a representative about how addiction treatment can help. Take the first step toward a healthier future and call today.