Alcohol Metabolism 301: Brain Dysfunction and Disease
As intuitive as it may seem, many do not realize that the substances we put into our bodies (cheeseburgers, aspirin and, yes, Mai Tai’s) impact every single cell and organ system in the body. Either directly or indirectly, eating a sleeve of PEZ candies impacts the function of our blood, breath, muscles, nerves, bones, hormones and excretory organs. Alcohol and drugs are no exception. In fact, they may be the worst affront to physical, psychological and spiritual health when used in a manner that exceeds the body’s ability to safely metabolize and eliminate them. And, considering how we have already discussed how the body processes alcohol and the impact it has upon the liver when used irresponsibly, it is time for us to look at the effects that alcohol and alcoholism can have upon the neurological health and the brain.
Fair warning: we are going to go into a little depth today, but all the information provided will help reinforce the importance of our discussion and the consequences of substance abuse.
Alcohol and NTs
The more immediate, or what I am going to call “tangible”, effects that alcohol consumption has upon the brain are well known. Slurred speech, double vision and impaired judgment occur fairly quickly and are the result of alcohol’s impact upon both excitatory and inhibitory neurotransmitters (NTs) in the brain. Going back to our discussion on the chemical effect of dependency, NTs are chemicals that allow communication between nerve cells within the brain whose function can be “depressed” by alcohol, impairing speech, vision, coordination and impulsivity.
More specifically, alcohol suppresses the release of glutamate, an excitatory NT that normally increases brain activity and energy, while simultaneously amplifying the effects of GABA, an inhibitory NT that suppresses the production of energy. In tandem, the suppression of glutamate and the amplification of GABA slow the brain’s super-highway of signal transmission to alter our ability to walk, talk, see and exercise sound judgment.
Unfortunately, alcohol interacts with a few other neurotransmitters that have the ability to alter neurological “intangibles” like mood and behavior as well. Referring again to the post mentioned above:
- Alcohol alters dopamine production and amplifies its effect to encourage reward-motivated behavior that can increase impulsivity, impair decision-making ability and reinforce the consumption of alcohol or other habit-forming substances. The longer and heavier one drinks, dopamine production and receptivity is diminished, which encourages greater consumption to establish and maintain feelings of normalcy.
- Short- and long-term alcohol exposure interferes with the production and recognition of serotonin, which is well known for its ability to contribute to feelings of happiness and wellbeing, a.k.a. more depression and anxiety.
- The habitual consumption of alcohol leads to beta-endorphin deficiency, which alters self-esteem, capacity to handle pain and feelings of hope or despair about the future.
Worsening the impact excessive alcohol consumption can have upon the brain, unused neurotransmitters that are unable to connect with their designated receptors may begin to combine with the acetaldehyde (see below) that has leaked from the liver to form psychoactive substances known as tetrahydroisoquinolines, or THIQs, that bind with opiate receptors in the brain and halt the production of endorphins, which create feelings of wellbeing.
Liver Dysfunction and Brain Health
The damage upon the brain’s neurotransmitter network caused by even a single alcoholic episode is enough to warrant concern, but the damage can get significantly worse once the alcohol dependency begins to develop and the liver loses its ability to detoxify alcohol. As we touched upon in my post Alcohol Metabolism 201: Liver Disease, alcohol travels to the liver where it is metabolized into less toxic, water soluble substances that are more easily eliminated by the kidneys. However, when consumed in excess, the liver may lose its ability to efficiently and effectively detoxify alcohol, which may allow one of the intermediates of alcohol metabolism, acetaldehyde, to spill into the blood increasing the brain’s exposure to extremely damaging free radicals derived from oxygen (a.k.a. a reactive oxygen species or oxidants). This leakage of oxidants may result in behavioral changes, loss of memory, an inability to concentrate and a potentially fatal brain disorder known as hepatic encephalopathy, which, without getting to involved in the nitty-gritty of the disease, can result in severe anxiety, depression, cognitive deterioration and problems with coordination and balance.
For more on the specifics of alcohol metabolism and acetaldehyde, please refer to my post ‘Alcohol Metabolism 101: An Introduction’ that lays it out in a pretty straightforward manner.
Alcoholism, Malnutrition and Nutrient Deficiency
The direct effect that alcohol has upon the brain is amplified by the poor nutrition that often accompanies substance abuse. From a very high level, the chronic ingestion of alcohol interferes with gastrointestinal integrity and function. Gastritis, characterized by severe inflammation and erosion of the mucosal lining of the stomach, is often the result of heavy alcohol use and may result in abdominal pain, indigestion, bloating, nausea, and vomiting, not to mention a hindrance in the secretion of digestive enzymes that facilitate the absorption and utilization of food nutrients. As the condition progresses, an alcoholic may exacerbate the problem by forgoing the consumption of food in favor of greater alcohol consumption to relieve the stress and pain caused by ill health.
Drilling down into a few of the specifics of alcohol induced nutrient deficiency, alcohol inhibits fat absorption and, therefore, the absorption of fat-soluble vitamins like vitamins A, E and D, which are vital to eye and bone health. Further, vitamins A, C, D, E and K, in addition to the entire vitamin B complex, can become depleted by chronic alcohol consumption, which interferes with wound healing, cell maintenance and energy production. Minerals like calcium, magnesium, iron and zinc can also be depleted by the heavy use of alcohol, which can lead to calcium-related bone disease and zinc-related night blindness and skin lesions. These minerals are also important in liver and brain function, meaning that alcohol induced nutrient deficiencies can compound the damage to these vital organs directly attributable to alcoholism.
The impact of alcohol on brain health is three fold. It interferes with short- and long-term brain function and often encourages nutrient deficiencies that exacerbate the issue.
I think it goes without saying, but considering the physical and psychological consequences of alcoholic behavior and alcoholism, it’s easy to see why it is often referred to as such an insidious disease.
Image courtesy of Boston Children’s Hospital’s Pediatric Health Blog