Alcohol-Related Brain Damage
University of South Wales
Beth yw Niwed i'r Ymennydd sy'n Gysylltiedig ag Alcohol?
Mae Niwed i'r Ymennydd sy'n Gysylltiedig ag Alcohol (ARBD) yn derm a ddefnyddir i ddisgrifio clwstwr o gyflyrau lle mae newidiadau strwythurol i'r ymennydd o ganlyniad i ddefnydd cronig, gormodol o alcohol dros sawl blwyddyn a'r diffyg maeth sy’n gysylltiedig â yfed gormod o alcohol.
Mae ARBD yn cael ei chyfeirio at fel ‘term ymbarél’ yn aml, yn yr ystyr ei fod yn ymdrin â nifer o gyflyrau cysylltiedig sy’n cynnwys Enseffalopathi Wernicke, Syndrom Korsakoff, Syndrom Amnesig Alcohol, Dementia sy’n Gysylltiedig ag Alcohol yn ogystal â nifer o gyflyrau eraill. Un peth hollbwysig i gofio am ARBD yw nad yw’n gyflwr sy’n gwaethygu’n gynyddol os yw unigolyn gyda ARBD yn cael ei chanfod yn gynnar. Mae ARBD yn gyflwr a gellir ei drin, gwella, ac mewn sawl achos ei wrthdroi’n gyfan gwbl.
Gall ARBD hefyd gwmpasu cyflyrau sydd ddim yn cysylltu’n uniongyrchol ag alcohol, er enghraifft anaf trawmatig i'r ymennydd sy'n deillio o ddamwain tra'i fod yn feddw. Mae termau eraill a ddefnyddir i ddisgrifio ARBD yn cynnwys nam neu anaf ymennydd sy’n gysylltiedig ag alcohol (Alcohol-Related Brain Injury; ARBI), nam niwrowybyddol sy’n gysylltiedig ag alcohol (Alcohol-Related Neurocognitive Impairment), ac ‘ymennydd gwlyb’ (‘wet brain’).
Beth sy'n achosi ARBD?
Mae alcohol yn achosi niwed i'r ymennydd mewn nifer o ffyrdd gwahanol. Mae rhagolwg rhywun sydd a ARBD yn aml yn dibynnu ar faint o ddifrod sydd wedi cael ei achosi a beth yw’r rheswm tu ôl i’r difrod. Rhan fwyaf o’r amser, diffygion maethol sy’n achosi ARBD, sy’n digwydd o ganlyniad i ddefnyddio alcohol yn ormodol dros gyfnod hir o amser. Diffyg yw hwn yn bennaf mewn Thiamin (Fitamin B1), sy’n chwarae rôl allweddol mewn sicrhau bod y neueseuon cemegol yn yr ymennydd yn cael eu hanfon yn gywir.
The causes of ARBD include the direct neurotoxic effect that alcohol has on the brain as alcohol is a toxin in itself. Liver failure can also further damage to the brain by a build-up of these toxins which are usually broken down by the liver. The experience of alcohol withdrawal can also cause ARBD as can cerebrovascular disorders that affect the blood vessels and stop the blood supply to the brain. Traumatic brain injuries are also a form of ARBD if they happen as an indirect result of alcohol. Because these causes may not lead to immediate effects and it takes a long time for symptoms to develop, some people may not accept that alcohol is responsible for their problems. Because they’re been drinking a lot of alcohol for a number of years, they may look for other reasons to explain their impairments.
Alcohol is a neurotoxic chemical and chronic use can cause damage to brain cells and lead to a reduction in both white and grey brain matter. One of the components that are damaged as a result of chronic alcohol exposure is the fatty, insulating structure called myelin. Myelin helps protect the axon of the neuron and aids in the transmission of the electrical signals throughout the brain. Thiamine (Vitamin B1) is crucial to the protection of myelin, however, a poor diet and a reduction in the absorption of this key nutrient may occur with alcohol abuse. This results in damage to the myelin and, consequently, the axon of the neuron is left exposed and the electrical signals are not transmitted as effectively.
Subtypes of ARBD
There are a number of subtypes of ARBD which were initially believed to be different conditions, however, as suggested by Jacques and Stevenson (2000) ARBD is best viewed as a spectrum of conditions that range in severity and overlap with one another. The most notable type of ARBD is Wernicke-Korsakoff syndrome (WKS) which was originally viewed as two separate conditions characterized by severe difficulties with memory and the inability to learn new information.
Korsakoff’s syndrome (KS) and Wernicke’s Encephalopathy (WE) are now viewed as two expressions of the same disorder, however, some people may receive a single diagnosis of Korsakoff’s syndrome which is viewed as a more severe disorder and the outcomes are less positive. Some subtypes of ARBD are:
Alcohol-Related Dementia is characterised by a general decline in cognitive functioning as a result of long-term alcohol abuse. Impairments are frequently seen in memory and processing and may include forgetfulness and confusion.
A condition that is characterized by substantial memory impairments as a result of excessive alcohol consumption and a severe deficiency of thiamine. Difficulties with forming new memories and confabulations (false memories).
This is a neurological condition (impacting the nervous system) and is an acute condition which also results from a severe thiamine deficiency. This condition includes weakness of the eye muscles, problems with balance, coordination, speech and confusion.
This condition is due to nerve tissue damage that can result in reduced mobility, numbness and unusual sensations in the limbs such as tingling and burning sensations.
This condition usually involves short-term memory loss, difficulty concentrating, and confabulations.
What counts as excessive alcohol use?
There are a number of people who might be drinking too much alcohol without realizing how much they are actually drinking. It might also be hard to notice when alcohol use becomes a problem and how much alcohol is too much. There isn’t a single clear-cut definition of alcohol misuse and perceptions of what alcohol misuse means or how much alcohol is too much.
Perceptions are likely to vary from person to person as well as there is no clear boundary on too much. There are however guidelines on how much alcohol counts as a risk for ARBD. An individual is considered ‘at risk’ of developing ARBD if they consume 35 units a week or more over a period of 5 years. A number of people within our societies drink alcohol, and research suggests that there are ‘safe’ levels of drinking that do not put us at risk of developing certain conditions.
Current guidelines in the UK recommend consuming no more than 14 units a week for males and females. This is roughly equal to 6 pints of beer or 6 medium glasses of wine spread evenly across the week. You should also have a couple of alcohol-free days in between the days that you do drink alcohol.
The Role of Thiamine
Thiamine (Vitamin B1) is a crucial nutrient that is required by the body for cell development and functioning. People who heavily misuse alcohol are at a substantial risk of developing a thiamine deficiency which may be responsible for or contribute to damage to the brain.
Thiamine plays a crucial role in cell functions and is an essential nutrient, especially for the brain, and a deficiency in this key nutrient can lead to serious damage to the brain. Thiamine deficiency is often a problem for people who drink very heavily.
The body cannot produce thiamine by itself, so it must be absorbed from food. People who consume large amounts of alcohol are at risk of thiamine deficiency as they may be eating a poor diet and replacing meals with alcohol, and their gut may be inflamed and less able to absorb nutrients. Foods containing thiamine include meat (especially pork), nuts, vegetables, bread, and breakfast cereals (especially those with oats), but people with ARBD (or at risk of it) may be prescribed extra dosed of thiamine.
Who is at risk of ARBD?
Traditionally, we have expected to find people with ARBD amongst populations who very obviously consume large quantities of alcohol for long periods of time, such as street drinkers. However, people from all social classes and all walks of life may develop ARBD if they are drinking at hazardous levels. Those who experience challenging life events may be more likely to drink large amounts of alcohol.
Many cases of ARBD have been described in individuals who have been in long-term employment with families, and we now know that stereotypes of street drinkers may not be accurate representations of those who have ARBD or who are at risk of developing ARBD. Some more specific factors that might put someone at risk of developing ARBD are:
