First off, thank you to everyone who has read my blog thus far. Nearly 400 people have viewed it since its inception as few weeks ago, with nearly 80 people viewing last week’s post alone. I truly appreciate the support.
This week’s question comes from Jeremy, who asked, “While camping out in Big Bear, the site coordinator warned us to be careful while drinking because ‘at this altitude, one drink is equal to three.’ Does alcohol have a stronger effect at higher altitudes? If so, what is the mechanism of action?” I chose this topic as a continuation of last week’s talk on neurobiology to broaden our knowledge of brain chemistry and the wider effects outside substances can have.
I too have heard that alcohol and altitude don’t play nice together. However, I have only heard this anecdotally and have never heard the reason. My best guess is that alcohol enhances the effects of mild hypoxia (low oxygen levels in the blood) by its usual mind-altering means. Let’s explore this topic a bit and see if we can get to a firmer answer.
But, before we get into the mix of alcohol and altitude, I want to start with a discussion of how alcohol affects the body. For the purposes of this article, let’s focus on alcohol’s ability to influence behavior; put another way, alcohol’s effect on the brain.
Alcohol’s behavior altering qualities stem largely from affecting neurotransmitters. Four major neurotransmitters come into play here. First is glutamate, which is an excitatory neurotransmitter involved in a variety of functions in the brain but primarily in long term potentiation, which is the adaptation of a neuron to a repeated stimulus over time and is thought to be the basis of memory. The second, gamma-aminobutyric acid, or GABA, is the main inhibitory neurotransmitter in the brain and is responsible for keeping nerve signals under control. Third is acetylcholine, which is responsible for muscle control, attention span, decision making, sensory information transmission, and dilation of various things, among other functions. And finally, serotonin, which you may recognize from last week’s post, which regulates pain signals, hunger, and a variety of other functions (see last week’s post here for more details).
As you can see, the relationship between alcohol and the brain is incredibly complex already, involving most of the major neurotransmitters present in the body. Generally, alcohol is considered a depressant, meaning that it reduces neurological function more and more with increasing dose. Little has been done to better understand the complex interactions involved with multiple neurotransmitters all changing at once in response to alcohol, which represents a hole in the literature. However, literature does exist on alcohol’s effects on individual neurotransmitters.
- Glutamate: Gonzales and Jaworski published an article in the 1997 edition of Alcohol Health and Research World that alcohol directly impairs the activity of the NMDA receptor, which is a key glutamate receptor. This impairment reduced the excitatory effects of glutamate, which is in line with alcohol’s depressant qualities. This is thought to impair memory and cognitive function. It also can inhibit the release of other neurotransmitters, namely acetylcholine.
- GABA: Brailowsky and Garcia published a review article in the June 1998 issue of Archives of Medical Research, that alcohol directly releases GABA and inhibits its re-uptake (similar to the SSRIs with serotonin in last week’s post). This enhances GABA’s inhibitory effect, which can yield muscle relaxation, anti-anxiety, and sedative effects.
- Acetylcholine: Kalant and Grose published in the December 1967 edition of The Journal of Pharmacology that alcohol inhibits the release of acetylcholine in the brain. This can caused decreased decision-making ability, as well as physical signs such as pupil dilation and lack of coordination. Aistrup, et al., conjectured in an article published in September 1998 in the journal Molecular Pharmacology that acetylcholine inhibition may affect release of other neurotransmitters, including the reward neurotransmitter dopamine.
- Serotonin: Lovinger published in the same Alcohol Health and Research World issue that alcohol causes an increase in brain serotonin levels, however it is unknown whether it causes more to be released or if it acts in a similar method to an SSRI. Regardless, even the short term serotonin spike involved in acute alcohol consumption (ie. a particular night out, not chronic drinking) can cause decreased body temperature, increased social interaction, improved mood, increased appetite, and altered sleep patterns.
Now that we have a good handle on the general effects of alcohol on the brain, let’s get back to the question. Roeggla, et al., published an article in the 1995 edition of the Annals of Internal Medicine a study involving alcohol’s impact on hypoxia adaptation at different altitudes. The study concluded that alcohol impaired the body’s ability to adapt to mild hypoxia present at high altitude (3000m, or roughly 9800ft), potentiating the effects. Fowles and Loeb published an article in the July 1992 edition of the Southern Economic Journal advocating for stricter drunk driving laws in higher altitude states due to the statistical effect of alcohol and altitude on traffic fatalities. In short, alcohol certainly does appear to have a greater negative effect on people at high altitude.
To answer the question as to why, the literature does not seem to support a direct answer. Gibson, et. al, published in the June 1981 edition of The American Journal of Medicine that mild hypoxia can have an impact on neurotransmitter activity in the brain, most notably reduction of acetylcholine. Wood, et. al, published in the October 2006 issue of Journal of Neurochemistry that hypoxia can also lead to an increase in GABA. As noted above, alcohol already decreases acetylcholine and increases GABA; the additional mild hypoxia may further contribute to its effects in this manner but I found nothing conclusive to this end.
In short, if you’re going up into the mountains and plan on drinking, be extra cautious and don’t drive. Alcohol and altitude really do not mix.
Thanks for sending in your question, Jeremy. As always, if you’re interested in submitting a question, please use the “Submit Your Question” tab at the top of the page.
Till next time folks,