The effects of alcohol hit your brain like a tidal wave. And you can go
from jovial, to falling-down drunk, to dead ?and it doesn't take very long to
get there.
First it suppresses the frontal lobes, then it goes to the
back of your brain, and then to the parts deep in the centre. Dr Izak Loftus,
forensic and anatomical pathologist from the Pathcare-Group explains.
Alcohol is a suppressant. It is called this, because it suppresses
the normal functions of your brain.
This suppressing effect on the brain is almost like a wave
crashing over your head. First it suppresses the frontal lobes, then it washes
further backwards over the parietal lobes, then to the parietal lobes, the
occipital lobes right at the back, then deeper into the brain to the cerebellum
and lastly to the diencephalon and the mesencephalon (midbrain), and then down
to the brainstem and the medulla oblongata.
This process is continuous, but certain functions, for example peripheral
vision, may already be affected at an earlier stage.
First effect: the jovial phase
The frontal lobes house the functions that
control, among other things, your inhibitions, self-control, willpower, ability
to judge and attention span.
Suppress it, and your self-confidence increases, you start getting jovial,
you become more and more generous, and start talking more. This is why alcohol
is seen as a good social lubricant.
This effect can already be detected with blood alcohol levels as low as
0,01g/100ml - in other words, while you are within the legal limit of
0,05g/100ml.
The problem is that even at this level, which is perfectly legal, your loss
of judgement ability and your changed personality already increase your risk of
dying an unnatural death, for example as a result of being in a fight.
Maybe you are better able to control yourself and your behaviour in this
phase as a result of good self-control, or education, and the onslaught of the
alcohol might pass by relatively unobtrusively. Maybe not.
Second effect: the slurring phase
The next parts of the brain that come
into the firing line, the parietal lobes are affected at a blood alcohol level
of approximately 0,10 g/100ml.
Then your motor skills become impaired, you have difficulty speaking, you
speak in slurred fashion (which oddly enough, you cannot hear yourself), you
start shivering, and complicated actions become very difficult to execute (I
always used to watched alleged drunk drivers trying to fasten their shirt
buttons ?an everyday activity that suddenly becomes as difficult as threading a
needle). At the same time your sensory abilities are hampered.
Third effect: the can't-see-properly phase
If the occipital lobe is
reached, the alcohol level is usually about 0,20 g/100ml.
Your visual perception ability becomes limited. You have increasing
difficulty to perceive movement and distance. Your depth perception becomes
impaired and your peripheral vision decreases. If you now drive at dusk, you
will have great difficulty seeing the little boy running after his ball, or your
fellow drinking buddy, staggering by the roadside.
Fourth effect: the falling-down phase
At about the alcohol level of 0,15
g/100ml the cerebellum becomes affected and keeping your balance could become
difficult.
With a bit of luck, your friends would by this time have lain you on the
ground somewhere safe.
Fifth effect: the down-and-out phase
We hope you are lying down in a safe
place, because at this stage the wave is crashing at 0,25 g/100ml over your
diencephalon and the mesencephalon (midbrain).
You become tired and very unsteady ?you are now probably out for the count.
You start shaking and you vomit. Maybe your reflexes will not be so badly
suppressed that you cannot protect your airways, otherwise you could inhale your
own vomit and die. Your consciousness is now suppressed, and you may be
comatose.
Sixth effect: in the valley of the shadow of death
Should the alcohol wave
wash further, driven by a blood alcohol level of 0,35 tot 0,40 g/100ml, and it
reaches your brain stem, including the medulla oblongata, you have
life-threatening problems. The centres controlling your breathing and your blood
circulation are suppressed, and you are busy dying.
The chronic drinker
These effects refer to the social drinker. Chronic
abuse of alcohol will increase someone's tolerance, and would therefore cause
these effects to become visible only when a chronic drinker has reached much
higher levels of alcohol in the blood than those mentioned above.
Usually the person would appear to be less under the influence at a specific
blood alcohol concentration (BAC), when the BAC is busy dropping, than when it
is busy increasing. This is called the Mellanby effect, and is the result of the
development of acute tolerance in the brain with regards to alcohol.