Of all the holidays in the year, St. Patrick's Day is the only one associated with drinking copious quantities of green beer.
While I can't speak to the "green" component - I have always presumed it is food colouring - we can talk about the effects of the alcohol component and what it does in the brain.
I should premise this by pointing out that "alcohol" to a chemist means something a little different than to the general public.
For chemists, there are lots and lots of alcohols such as sugars and DNA.
To a chemist, alcohols are organic compounds that contain a hydroxyl or -OH group.
Methanol is the simplest of all the alcohols. It is composed of a single carbon atom attached to three hydrogen atoms and a hydroxyl group.
It is also toxic and called "wood alcohol."
Methanol is a common by-product when making moonshine and methanol poisoning was a severe problem during prohibition.
Methanol can get you drunk, but it can also kill you.
Ethanol, on the other hand, is the alcohol that we like to consume. In fact, many animals from tiny shrews to fruit bats to moose frequently enjoy a little ethanol, although many do so unintentionally.
Ethanol is not much more complex than methanol, having just two carbon atoms with one carbon atom attached to an -OH group.
It is also poisonous, but at very much higher doses.
The toxicity depends upon factors such as gender, body mass, rate of consumption and tolerance. Typically, a blood alcohol factor of over 0.30 per cent can lead to alcohol poisoning and can be fatal. For a 55 kg woman, that is about eight drinks in an hour. For a 75 kg man, it is closer to 11 drinks.
At much lower doses (one to two drinks over a one-hour period) ethanol-containing beverages produce a pleasant sensation - a feeling of relaxation and mild euphoria.
Ethanol is what we conventionally call "alcohol" and is traditionally classified as a depressant.
This designation arises because at high doses, it slows down the central nervous system.
The classic symptoms of excessive consumption - slurred speech, diminished cognitive abilities and a lack of coordination - are all a consequence of ethanol's inhibitory interactions across a variety of areas in the brain.
However, even Aristotle noted 2,000 years ago that ethanol can drive one into a frenzy.
Intoxication can lead to boisterous behavior, talkativeness, aggression and other behaviors that are more typical of a stimulant than a depressant.
Over the past few decades, scientists have come to realize that ethanol affects brain chemistry in a much more profound way than most other drugs. It does so by altering the levels of a variety of neurotransmitters.
Principal amongst these is gamma aminobutyric acid or GABA which is an inhibitory neurotransmitter in the brain. Ethanol enhances the effectiveness of the GABA receptors.
It applies the brakes to the brain's functions and results in the sluggish movements and slurred speech.
Ethanol also affects the stimulant glutamate, which is the most common excitatory neurotransmitter in the brain.
Glutamate plays a role in muscle control, speech, and automatic body functions such as breathing and regulation of the heart rate.
Ethanol binds to the glutamate receptors and interferes with its ability to open normally.
This results in decreased function across all of these systems.
Further, recent research has indicated that the inhibition of glutamate receptors may also interfere with our ability to learn or make new memories.
These interactions result in many of the common symptoms of being drunk.
For example, while ethanol inhibits the formation of new memories, it does not affect the ability to recall stored memories. With a lack of inhibitions, this often leads to the rambling trips down memory lane common with intoxicated people even though they don't remember their ramblings later.
Ethanol also increases the amount of dopamine in the brain's reward centre.
This results in the mild euphoria that accompanies moderate drinking. Dopamine is tied to our sense of well-being and pleasure.
The actions of ethanol can be self-reinforcing as a consequence.
While consuming ethanol, the sensations can be quite pleasant. However, detoxification of ethanol is not without its consequences. Ethanol interferes with the antidiuretic hormone (ADH) in the kidneys. Most of the water in the kidneys is recycled but with ADH blocked this water is not reabsorbed. The result is mild dehydration which leads, in part, to dry mouth, nausea, and a throbbing headache.
The trick is to drink plenty of water. But it doesn't totally alleviate the symptoms as there are other compounds in beer, wine and hard liquor that can affect the body.
The only real way to avoid the side effects of a night on the town is to not drink alcohol in the first place.
But green beer? Cheers everyone!
