Alcohol and dementia – Many people are not aware that alcohol consumption can be a potential risk factor for dementia. How can alcohol influence our risk for dementia? Is this a risk we need to be aware of when consuming alcohol?
Let’s find out.
Alcohol
Alcohol is the most common accepted societal drug. Most of us consume it as beer or wine, with studies having shown that in economically developed countries up to 80% of men and 60% of women drink alcohol throughout their lives. But despite its wide acceptance, alcohol remains a drug, which leads in up to 20% of people to an alcohol-use disorder and in the worst cases to alcohol dependence. On top of that, alcohol is also one of the highest contributors to fatal and non-fatal accidents worldwide. Despite its wide acceptance, it is a good reminder that alcohol is in fact a drug and can have significant health implications.
However, not everything is bad about alcohol, as it can be an excellent ‘social glue’ by making people more relaxed and hence being more convivial. This relaxation has, in fact, a physiological reason with alcohol being not only a muscle relaxant – just thinking of all the tipsy people stumbling about – but also affects certain chemicals in our brain which are important for our inhibition. Alcohol reduces the function of those chemicals and we become therefore less inhibited or more impulsive when we drink alcohol – many embarrassing stories can be told based on this lack of inhibition. The final aspect is that alcohol affects directly our memory, with memory loss a common symptom after a night of heavy drinking. In particular, alcohol seems to affect the laying down of memories, creating the infamous black-outs after one too many drinks.
Now, you might think that this sounds much more like young people going out partying and you are right, the majority of ‘heavy’ drinking is done in our early adulthood with binge drinking being common at that age. However, we often underestimate how much drinking can be also part of our middle-age life or even in older age. Instead of more public drinking during our younger age, think going out with friends for partying, most of the alcohol consumption happens in middle-age or older life happens in private, either as a couple sharing a bottle of wine or even alone drinking. This ‘private’ aspect of alcohol consumption in later life, makes it much harder to notice for people from the outside when an alcohol use disorder is developing, as most of the consumption is hidden. I still remember my great-grandfather, who insisted until to a very late age, to pull up the weights for his cherished grandfather clock twice a day. Only after his death, did we discover that he had a bottle of cognac hidden in the bottom of the grandfather clock, allowing him a quick sip when ‘checking the clock’. Talking about private drinking!
The other aspect about alcohol is that it is quite easy to ‘slip’ into a routine of drinking quite significant amounts of alcohol without even realising that one is doing so. For example, one has a first glass after work or picking up the kids to ‘take the edge off the day’. This is followed by another glass during dinner preparation with another glass or two in front of the TV. This might sound not much but we should consider that each standard glass of beer or wine is ~2 alcohol units (Alcohol units are a way to calculate how much alcohol one consumes per glass. It is calculated by multiplying the alcohol percentage of the drink by the volume consumed and divide it by 1000). Coming back to our example, if we would consume 3-4 glasses each night this would result in us consuming ~6-8 alcohol units per night. This might not sound much, but current public health guidelines in the UK state that men and women should not consume more than 14 units per week on a regular basis. According to our example, we would hit this limit within 2 days and many people would not consider this significant alcohol consumption but according to public health guidelines it is. The reason is that research has shown that health consequences significantly deteriorate beyond 14 units of alcohol per week. The research evidence is strong that drinking beyond 14 units of alcohol per week increases our risk for a whole host of serious diseases, such as cardiovascular disease, diabetes, cancer and even dementia.
So, how does alcohol affect our brain health and increase our risk for dementia?
Alcohol and brain health
Alcohol affects our brain on several levels. It affects the functioning of several neurotransmitters in our brain, which in turn can affect our behaviour and memory. Alcohol also impacts our cardiovascular health, which we know is important for our brain. Both factors not only impact our brain health but also are known to increase our risk for dementia. However, one factor that is particularly relevant for our brain health is that that alcohol also has a direct effect on our nerve cells by literally killing them, or to put it in scientific terms, alcohol is neurotoxic.
We all had the feeling after a hard night out that we must have lost some brain cells but that is not only a feeling but reality. Alcohol is known to be highly neurotoxicity, which means that it kills nerve cells when they are exposed to it. You might remember from my previous articles that the blood brain barrier is a key protective mechanism for the brain to protect itself from poisons or toxins. Does that blood brain barrier protect us from alcohol?
This is a key question, as research has shown that ethanol (the key molecule of alcohol) can easily cross the blood brain barrier. This means that an even small amount of alcohol enters the brain and can potentially wreak havoc. This is when neurotoxicity comes into play, as nerve cells die when being exposed to certain concentrations of alcohol. It means that we literally lose nerve cells when drinking (too much) alcohol. Our brain can compensate for some lost nerve cells and we can generate some limited new nerve cells, however, we can see that if we are drinking excessively and for a long time then our risk of losing nerve cells increases significantly. Importantly, the brain regions most affected by alcohol consumption are the regions responsible for our memory and decision-making. In people, with severe alcohol disorder, we can see therefore changes in decision-making behaviour, such as being more erratic or impulsive, as well as memory problems. In the worst cases, this can lead to a Wernicke-Korsakoff syndrome. In a Wernicke-Korsakoff syndrome, named after two clinicians from the 19th century who described the first cases, people who have long-term excessive alcohol consumption develop a sudden memory loss. These people have difficulties in laying down memories as the memory regions in their brain stop working. The sudden memory loss in Wernicke-Korsakoff syndrome is an effect of a long-term alcohol use disorder, which results in vitamin B1 deficiency leading to memories not being laid down anymore.
Still, even without developing a Wernicke-Korsakoff syndrome, people with alcohol use disorders have significantly lower memory than people of the same age. It should come, therefore, maybe not as a surprise that people with alcohol use disorders also have an increased risk for dementia, indeed their risk is up 3-4 times higher than the rest of the population. But clearly, alcohol use disorder and particularly Wernicke-Korsakoff syndrome are the extreme ends of alcohol consumption and the majority of people will not fall within that spectrum.
How about more ‘standard’ alcohol consumption? Can it also increase our risk for dementia?
Alcohol and dementia
This has been an ongoing discussion for many years and is actually quite difficult to establish since there are few long-term studies that have investigated the impact of alcohol use on ageing in a healthy population. Fortunately, a recent study investigated this issue in such a cohort. The results were quite intriguing since they showed that there was no increased risk for dementia in people drinking between 1 and 14 units per week through their middle-age and early older age. However, there was an up to 4-times higher risk of dementia for people drinking more than 14 units per week. This increased risk for dementia was linear with the amount of alcohol consumed, in other words, the more alcohol consumed during middle age or early old age the higher risk for dementia. This makes sense if we consider the neurotoxic effect of alcohol, basically the more of a toxin you consume the great the risk for dementia. Since alcohol affects our memory system already, we might weaken this part already for any development of dementia in the future.
So, does this mean it might be best not to drink any alcohol at all and become abstinent?
Not quite. This is, in fact, quite a controversial topic as several research studies over the years, including the one above show that people who abstinent from alcohol have actually a slightly increased risk for dementia. How can that be? Shouldn’t the risk be the lowest for not drinking any alcohol at all?
Indeed, a very good question that is still controversially discussed in the alcohol research community. It clearly makes sense that less alcohol should be good for us, however, alcohol can have some beneficial effects on our brain. For example, it can reduce the ‘stickiness’ or viscosity of blood, which can help to avoid blood clots, and it also can increase the healthy cholesterol (so-called HDL cholesterol) in our blood. Both these factors are known to decrease our risk for dementia, and particularly vascular dementia, so it is feasible that some lower amounts of alcohol can be good for us. However, and it is a big ‘however’, there is a caveat as most studies cannot distinguish between people who have been their whole life abstinent from those who became abstinent, because maybe they had an alcohol use disorder. The latter group, in particular, might still have an increased risk for developing dementia in the future because they had an alcohol use disorder in the first place and hence their risk for dementia is increased, even though they are now abstinent. In the end, the jury is still out as to whether alcohol abstinence really increases our risk for dementia.
Where does this leave us?
Summary
Overall, there is good evidence that if we adhere to public health recommendations for weekly alcohol consumption, such as in the UK to consume <14 alcohol units per week, there is no increased risk for dementia in the future. I think this should be reassuring news, as we can still enjoy a glass or two without increasing our risk for dementia. But I hope the article also highlights how potentially dangerous alcohol is for our health in general. This is often forgotten as alcohol is so widely accepted across societies but we should remind ourselves, that with any drug, the dosage is a key factor to remain within healthy parameters. If we exceed those parameters, such as public health recommendations we can increase our risk for dementia by up to 4 times over our lifetime. Simply said, the more alcohol we consume the higher our risk for dementia (and potentially other health conditions) will be. Finally, whether alcohol abstinence increases our risk for dementia or not is still controversially discussed.
Time to raise a (small) glass (within our weekly 14 units) to that!
Links
- https://www.nhs.uk/live-well/alcohol-support/calculating-alcohol-units/
- https://www.cdc.gov/alcohol/faqs.htm
- https://www.who.int/health-topics/alcohol#tab=tab_1
