The Effects of Alcohol on Mental Function

Drinking can distort the thought process to the point where one can
endanger themselves and others- especially if behind the wheel.  But
there are also very sobering long term mental health risks associated
with alcoholism.  

Alcohol is a chemical, like the active chemicals in other psychoactive
drugs, that can pass through the blood brain barrier.  After entering the
blood stream alcohol passes into brain where it begins to affect synaptic
transmission- the communication from one brain cell or neuron to the
next.  This interference in synaptic transmission is what produces the
effect of intoxication.  But alcohol does more than effect the way that
energy and chemicals are metabolized in the brain, it also physically
degrades the neurons themselves.

Experts have shown that prolonged consumption is associated with
lowered neuron number and actual brain shrinkage.  Data from autopsy
studies has shown that the brains of drinkers are smaller and lighter than
the brains of nonalcoholic adults of the same age.  Unfortunately it
seems that the damage of alcohol consumption is actually greatest in the
frontal lobe, the area associated with higher thought.  Autopsy studies
and functional imaging techniques have revealed that many areas, each
with important functions, can be damaged resulting in several different
types of impairment.  

Evidence of this degradation can be found in the cognitive processing
abilities of alcoholics, even ones that have abstained from alcohol for
months or years.  These individuals have certain processing deficits that
can affect their behavior.  It is very common for an alcoholic to be
visuospatially impaired.  People with visuospatial impairment find it hard
to complete simple tasks such as reading a map or putting a puzzle
together.  Alcohol consumption is also known to create memory deficits
known to impair the aptitude for simple tasks and destroy long term
memories.  The cerebellum is also a susceptible area and damage to it
impairs muscle coordination and movement.  These deficits are often
grouped into a broader category called alcohol dementia.

Like other psychoactive drugs alcohol can make some memories difficult
to retrieve.  Even more unsettling though, by destroying neurons it
decreases our ability to form new memories- it impairs our ability to
learn.  If alcohol can so severely affect the lives and mental health of
alcoholics one can imagine that over time even moderate drinkers will
experience some of the same effects.

Check out the following references for more information:

Agartz, I.; Momenan, R.; Rawlings, R.R.; et al. Hippocampal volume in
patients with alcohol dependence.
Arch Gen Psychiatry 56(4):356-363,

Hommer, D.; Momenan, R.; Ragan, P.; et al. Changes in CSF,
ventricular, gray and white matter volumes in female alcoholics
measured by automated segmentation of MRI images.
Alcohol Clin Exp
20(2 Suppl.):33A, 1996b.

Pfefferbaum, A.; Sullivan, E.V.; Mathalon, D.H.; et al. Frontal lobe
volume loss observed with magnetic resonance imaging in older chronic
Alcohol Clin Exp Res 21(3):521-529, 1997.

Rosenbloom, M.J.; Pfefferbaum, A.; and Sullivan, E.V. Structural brain
alterations associated with alcoholism.
Alcohol Health Res World
19(4):266-272, 1995.

Sullivan, E.V.; Rosenbloom, M.J.; Deshmukh, A.; et al. Alcohol and the
cerebellum: Effects on balance, motor coordination, and cognition.
Alcohol Health Res World 19(2):138-141, 1995b.

Volkow, N.D.; Hitzemann, R.; Wang, G.-J.; et al. Decreased brain
metabolism in neurologically intact healthy alcoholics.
Am J Psychiatry
149(8):1016-1022, 1992.
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