The Neurologic  Effects of Alcohol 

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In order to understand why we like to drink, we must understand what the drug does in our brain.  It has three direct effects and one important indirect effect

Effect #1- Increase in GABA inhibition

GABA is a neurotransmitter that inhibits a target nerve; that is, it makes it less likely to fire.  Inhibition will have a calming effect; this is how medicines like Valium work.  In higher amounts it causes the dis-coordination, memory loss, disinhibition of behavior (which leads to impulsiveness).  In dangerously high doses-people pass out and breathing can be reduced.

Increased GABA activity during withdrawal causes agitation and tremors and can lead to seizures, hallucinations and DTs

Effect #2-Decrease in Glutamate Receptor Activity

Parallel to augmenting the inhibition of the GABA receptor; the drug also blocks an excitatory effect  of the excitatory neuro-transmitter glutamate.  This is additive to the effects on GABA and contributes to the depressant effects of alcohol.

Therefore-we see increasing depressant effects at increasing levels of alcohol with the following symptoms seen at different level of alcohol concentration:

.050%: (about two drinks for average weight male) Loss of emotional restraint, vivaciousness, feeling of warmth, flushing of skin, mild impairment of judgment

.100% (4 drinks) slurring of speech, loss of control of fine motor movements (such as writing), confusion,      emotionally unstable,

200 mg%: (8 drinks) Very slurred speech, staggering gait. double vision, lethargic but able to be aroused by voice, difficulty sitting upright in a chair, memory loss

300 mg/%: (12 drinks) Stuporous, able to be aroused only briefly by strong physical stimulus (such as a face slap or deep pinch),

400 %: (16 drinks) Comatose, not able to be aroused, incontinent (wets self), irregular breathing

500 %: Death possible,

Effect # 3- Seratonin Receptor Augmentation

The effect of alcohol is more difficult to characterize because of the myriad of different seratonin receptors.  The main effect is that it increases seratonin activity at least in some of the key receptors being studied.  This increases dopamine and reduces appetite.  One of the characteristics of a person who is at increased risk for alcoholism is decreased seratonin levels; perhaps these decreased levels put them at risk for depression and otherwise not being satisfied.  By increasing seratonin activity with alcohol, they may be self-medicating a chronic depressive or anxious state 

Effect #4-Increase in B-endorphin Levels 

This is a key effect to understanding the pleasurable effects of drinking.  B-endorphin is the natural opiate in the brain.  Alcohol seems to increase its' level which leads to a euphoric response.  The endorphin in turns increases dopamine which leads us to repeat the behavior.  When this effect is blocked with Naltrexone, alcoholics stop drinking.

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