Dear Neurontic

I'm told I went out last night and that many beers were consumed, but I have no memory of the event. Why does too much hooch make us forget? And does the fact that I "blacked out" mean I should reserve a place in rehab?

Sincerely,
Chastened Boozehound

Dear Boozehound,

You probably never thought you'd have anything in common with the main character from Memento, but, guess what? Now you do. See, Leonard was suffering from a condition known as anterograde amnesia brought on by severe head trauma, which kept him from transferring new experiences into long-term memories. His memories of everything that happened prior to his brain injury remained in tact, but that's where time stopped for Leonard. He carried on living, but none of his new experiences made it into the proverbial hard drive. Leonard woke up each morning as the same person he was the day of his attack.

Blackouts can be understood as temporary bouts of anterograde amnesia--they are hiccups in your personal chronology brought on by excessive drinking. They come in two flavors: fragmentary and en bloc. Fragmentary blackouts result in the loss of slices of time, as the name suggests. Like a television with bad reception, your ability to retain memories weaves in and out, leaving you with a spotty recollection of events. An en bloc blackout -- the kind you experienced -- is characterized by the failure to retain any information about a particular block of time. You, like Leonard, woke up this morning with a significant gap in your personal history.

Blackouts are often confused with "passing out," but there's a key difference. Passing out results in a loss of consciousness, whereas when you black out, you appear totally cognizant. People are often highly functional when blacked out and can even accomplish cognitively demanding tasks, like driving (though I fervently hope you won't try this at home), they just won't recollect anything they've done.

At present, scientists believe that alcohol compromises memory formation by interrupting normal processing in the hippocampus. Recent studies have shown that ethanol suppresses "the activity of pyramidal cells," in the region of the hippocampus known as CA1, and disrupts long-term potentiation, the biochemical process responsible for creating memories. As scary as this sounds, the deficit in function is temporary and blackouts haven't been correlated with long-term cognitive problems. The amount of alcohol required to bring about a blackout varies from person to person, which makes it impossible to come up with an "anti-blackout formula." But blackouts appear to be triggered by a rapid increase in "blood-alcohol concentration," so try to avoid drinking cocktails in large gulps or in quick succession.

As for whether last night's debauchery destines you for a stint at Betty Ford, the answer is: Not unless this type of behavior becomes customary. Blackouts have long been associated with alcoholism, but recent research indicates that the correlation may be circumstantial. Many alcoholics do blackout, but blacking out doesn't necessarily mean you are an alcoholic. Scientists now believe that susceptibility to blackouts may be genetic. Of course, this doesn't give us unreformed drinkers free license to imbibe at will. Let's face it, no one wants to be like Leonard, even for a short time.