What happened last night? Ellen wakes up in her bed, she is somewhat confused, the daylight is blinding, and her mouth feels like cotton balls. She rolls over to avoid the glaring morning light and discovers a naked male body in bed next to her; he is snoring. Ellen feels a growing sense of panic. She checks and is not wearing panties, or anything for that matter. She wants to scream, but is afraid she will awaken the intruder. She recalls meeting Angie at Gino’s. Then what? Nausea overwhelms her; she sneaks into the bathroom. The stranger joins her in the bathroom, she doesn’t recognize a single feature of his face, but he reminds her they had a hell of a time together. She is afraid to ask questions. She doesn’t remember. She is engaged to be married next week. Later that afternoon Ellen goes to the police station to report that she was raped. What happens now?
What Exactly is a Blackout?
Alcohol can interfere with the brain’s ability to form new memories. As the amount of alcohol consumed increases, so does the magnitude of the memory impairments. It is like a switch turns to off in the brain when a person’s blood alcohol content reaches a certain level. Blackouts represent episodes at which time a subject participates in events that he/she later cannot remember. This type of amnesia is referred to “alcohol related amnesia” and is very similar in character to other types of anterograde amnesia. In these types of amnesia an individual cannot form new memories, but previous memories are not erased. “En bloc” blackouts are stretches of time where the drinker has absolutely no memory at all. Blackouts do not involve a loss of consciousness. However, blackouts may precede passing out or losing consciousness. A subject, who has usually consumed large quantities of alcohol rapidly, can still engage in complicated activities from holding a conversation, to driving, to dancing, to having sexual relations, etc. However, he/she may not remember all, most, or even any of his/her actions or behaviors. Recent studies indicate that blackouts are much more common among social drinkers (including college drinkers) than was previously assumed. Fragmentary blackouts (often referred to as gray-outs or brown-outs) are episodes when the drinker’s memory is spotty. They may remember some things, especially if reminded by others.
The switch mentioned above is actually in a part of the brain called the hippocampus (located in the forebrain). The hippocampus plays major roles in the formation of new memories related to experienced events, accessing previous memories, and spatial navigation (which is why an intoxicated individual staggers around). Quite simply, alcohol disrupts the functioning of the hippocampus. Prolonged and chronic alcohol abuse/dependence can permanently damage the hippocampus. This is one of the first regions of the brain to be damaged in Alzheimer's disease and Alcohol Wernicke-Korsakoff Syndrome (alcohol induced dementia)
Blood Alcohol Content
When a person consumes alcohol, it is absorbed in the stomach and small intestine. After this absorption, the alcohol enters the bloodstream by dissolving into the water of the blood. The rate of absorption depends on several factors: the concentration of the alcohol, the type of alcohol, an empty versus full stomach, and gender. Alcohol leaves the body in three ways: 5% is eliminated by the kidneys, 5% by the lungs (how breathalyzers measure alcohol levels), the rest is broken down by the liver into acetic acid. Blood alcohol content (BAC) is the concentration of alcohol in blood. It is measured as mass per volume. For example, if a person has a BAC of 0.08% it means he/she has 0.02 grams of alcohol per 100 grams of his/her blood. Generally, it takes one hour to eliminate one alcoholic drink. (“And how big was that beer sir?”).
The Effects of a Rising Blood Alcohol Level