Recently, the Indiana State Fair served its
first alcoholic beverage since 1946. With the popularity of local breweries and
wineries on the rise in Indiana – nearly a hundred of each in the Hoosier State
– a reversal of the near-70 year alcohol drought at the State Fair seemed
inevitable.
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The logo for the Beer and Wine Exhibit 2014 at the Indiana State Fair
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Meanwhile,
in Indiana and beyond, many scientists are buzzing about trying to understand
exactly what alcohol does to our brain. From time to time, researchers lace a
rodent’s drinking water with varying amounts of ethanol in order to observe how
this impacts their zig-zagging through mazes. Despite consuming alcohol for
millennia, we remain remarkably ill-informed regarding how alcohol affects the
nervous system. Why do we consume alcohol? How does it affect us neurologically
in the short-term, and why do we keep going back for more? The answers are
complex, but we are beginning to see them without beer goggles.
Going
back at least to 8,000 B.C., the pages of history are splashed with examples of alcohol
usage, the reasons ranging from medicinal (analgesic and antiseptic), religious (Communion wine), aesthetic (perfumes and cosmetics), preservative (safeguarding of food), industrial (fossil fuels), financial (barter) and recreational (drinking in times of
merriment and sorrow to alter one’s mood). The mighty powers behind
constructing the Pyramids of Giza rationed payments for their laborers in
measures of beer. The Middle Ages and well beyond saw numerous reports of
alcohol (primarily beer) being safer to drink than water - until the Germ Theory
of Disease helped make two parts of hydrogen and one part oxygen safe to imbibe.
The Royal Navy of the United Kingdom received a daily rum ration until the
1970s, when someone of importance finally became worried that operating heavy
machinery might be precarious while under the influence.
Many,
then, are the uses of alcohol, and diverse are instances of its enduring
consumption, inherent in legions of cultures for thousands of years. For all
the other ways in which the world has changed, in some ways the consumption of
alcohol seems little different today. As in ancient and medieval times, we
drink to please others and we drink to please ourselves.
While
the liver is the key organ that metabolizes alcohol, the majority of the
effects we feel after having thrown back a few (or a few too many, depending on
the occasion) are primarily neurological. It is important to understand that alcohol
is more than simply a depressant. Alcohol is a complex drug that causes
variable effects based on the amount ingested. It affects a variety of
neurological pathways and targets different structures in the brain, resulting
in a cocktail of symptoms not easily explained by a single molecular
alteration. After minutes of ingestion, alcohol enters the blood stream and
readily crosses the blood-brain barrier, typically a highly selective barrier
between the circulating blood and brain fluid, and acts on a number of
receptors both directly and indirectly. Even moderate alcohol consumption can
have adverse effects on sleep patterns and temperature regulation, which is controlled
by a small almond-shaped structure located just above the brainstem known as
the hypothalamus. While a nightcap may help you feel drowsy, larger quantities
of alcohol affect REM sleep, causing restlessness and wakefulness through the course
of the night.
Those
who have had too much are afflicted with cerebellar defects, such as difficulty
walking and impaired motor coordination. Alcohol can also do a number on the
cerebral cortex, which is responsible for judgment, cognition, planning, and social
interaction. Some reports suggest that alcohol can bind up to 100 independent
receptors in the brain, and the various locations of these processes in the
cranium determine the specific changes in behavior. Other symptoms associated
with drinking include changes in memory and emotion, slurred speech, and
blackouts. Small to moderate quantities of
alcohol have also been reported to decrease brain volume.
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Low and moderate
alcohol users show a decrease in adjusted brain volume based on magnetic
resonance imaging results in the Framingham Offspring Study cohort (Paul et al.
JAMA Neurology 2008)
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Alcohol also alters
the release of numerous neuro-transmitters and neuropeptides, which are chemical
messengers and protein-like molecules, respectively, involved in transmitting signals
in the brain. For example, alcohol decreases the release of glutamate, the key
excitatory neurotransmitter in the brain, while increasing the amount of GABA,
an inhibitory neurotransmitter, potentially resulting in a slowdown of brain
function. All these consequences seem negative, but there’s a catch: booze increases the production of dopamine in
the “reward center” of the brain. This creates a positive feedback loop, making
us want more and more of this elixir.
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| A number of different structures in the brain are affected by the consumption of alcohol. In particular, the ‘pleasure center’ is responsible for the effects of the dopamine reward pathway and the limbic system can lead to changes in memory and emotion |
Indeed,
there are a number of reasons why libations are such a central part of our
life. Here’s a small excerpt. First and foremost, we like it! This pleasure can
be explained neurologically by the
activation of the dopamine-reward pathway, socially
by the fact that it is an event that often brings people together (be it in
times of merriment or sorrow), and psychologically
by how it is a low risk/high reward activity and relieves stress, helping one
cope with emotional turmoil.
If viewed from an evolutionary perspective,
moderate alcohol consumption hardly affects fitness: Although the Porter in
Shakespeare’s Macbeth says that drink
“provokes the desire but takes away the performance,” science tells us that
alcohol can bolster both. So spirits, unlike the painful fear of heights, seem
no powerful threat to either survival or procreation. Additionally, the “drunken monkey”
hypothesis put forth by Dr. Robert Dudley suggests
that we drink because we associate alcohol with a nutritional reward, as our
anthropoid ancestors primarily subsisted on ripe fruits that contained low
levels of ethanol. Since moderate and chronic alcoholism are associated with a
number of vitamin deficiencies, such as folate, vitamin B12, vitamin A, and
calcium, I have difficulty believing that alcohol consumption is, in fact, an
evolutionary hangover, but this argument has been made from time to time.
However, as with most things in life, consuming alcohol in moderation can maximize
its positive effects while minimizing the risk associated with consumption.
So as
you weave your way to the Grand Hall to the Beer and Wine
exhibition at the State Fair, right after
having scarfed down your deep-fried Twinkie and a few shucks of corn, if you
down that beer (or three, the limit imposed at the State Fair this year), it
won’t be because you have to. You’ll swill that brew because you want to.
Contributed by: Aarti Chawla
Diamond I, & Messing RO (1994). Neurologic effects of alcoholism. The Western journal of medicine, 161 (3), 279-87 PMID: 7975567
Németh Z, Kuntsche E, Urbán R, Farkas J, & Demetrovics Z (2011). Why do festival goers drink? Assessment of drinking motives using the DMQ-R SF in a recreational setting. Drug and alcohol review, 30 (1), 40-6 PMID: 21219496
Paul CA, Au R, Fredman L, Massaro JM, Seshadri S, Decarli C, & Wolf PA (2008). Association of alcohol consumption with brain volume in the Framingham study. Archives of neurology, 65 (10), 1363-7 PMID: 18852353
