Brain Shrinkage
Previous studies have demonstrated that the brains of alcoholics are smaller, lighter and "shrunken" when compared to nonalcoholic brains.The outer layer of brain, also called the cerebral cortex or gray matter, controls most complex mental activities.The cortex is filled with nerve cells, also called neurons, that connect by single long fibres to different cortical regions and other neurons deep inside the brain and spinal cord. These nerve fibres make up white matter, which comprises the 'hard wiring' of the brain.Most of the fibres are insulated by a material called 'myelin' that is similar to the plastic coating around electrical wires. Nerve cells also have shorter and more numerous fibres or processes called dendrites with many fine branching processes – similar to the root system of a tree – that allow them to 'talk' with neighbouring neurons, often as many as five to 10,000 at a time.Alcohol appears to be particularly damaging to the "white matter" or "hard wiring" of the brain, and can also cause shrinkage or retraction of neuronal dendrites; however, the damage appears to be at least partially reversible with abstinence.
Damaging Effects On The Brain
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Difficulty walking, blurred vision, slurred speech, slowed reaction times, impaired memory: Clearly, alcohol affects the brain. Some of these impairments are detectable after only one or two drinks and quickly resolve when drinking stops. On the other hand, a person who drinks heavily over a long period of time may have brain deficits that persist well after he or she achieves sobriety. Exactly how alcohol affects the brain and the likelihood of reversing the impact of heavy drinking on the brain remain hot topics in alcohol research today.
We do know that heavy drinking may have extensive and far–reaching effects on the brain, ranging from simple “slips” in memory to permanent and debilitating conditions that require lifetime custodial care. And even moderate drinking leads to short–term impairment, as shown by extensive research on the impact of drinking on driving.
A number of factors influence how and to what extent alcohol affects the brain including
We do know that heavy drinking may have extensive and far–reaching effects on the brain, ranging from simple “slips” in memory to permanent and debilitating conditions that require lifetime custodial care. And even moderate drinking leads to short–term impairment, as shown by extensive research on the impact of drinking on driving.
A number of factors influence how and to what extent alcohol affects the brain including
- how much and how often a person drinks;
- the age at which he or she first began drinking, and how long he or she has been drinking;
- the person’s age, level of education, gender, genetic background, and family history of alcoholism;
- whether he or she is at risk as a result of prenatal alcohol exposure; and
- his or her general health status.
Blackouts and Memory Lapses
Alcohol can produce detectable impairments in memory after only a few drinks and, as the amount of alcohol increases, so does the degree of impairment. Large quantities of alcohol, especially when consumed quickly and on an empty stomach, can produce a blackout, or an interval of time for which the intoxicated person cannot recall key details of events, or even entire events.
Blackouts are much more common among social drinkers than previously assumed and should be viewed as a potential consequence of acute intoxication regardless of age or whether the drinker is clinically dependent on alcohol.772 colleges undergraduates about their experiences with blackouts and asked, “Have you ever awoken after a night of drinking not able to remember things that you did or places that you went?” Of the students who had ever consumed alcohol, 51 percent reported blacking out at some point in their lives, and 40 percent reported experiencing a blackout in the year before the survey. Of those who reported drinking in the 2 weeks before the survey, 9.4 percent said they blacked out during that time. The students reported learning later that they had participated in a wide range of potentially dangerous events they could not remember, including vandalism, unprotected sex, and driving.
Equal numbers of men and women reported experiencing blackouts, despite the fact that the men drank significantly more often and more heavily than the women. This outcome suggests that regardless of the amount of alcohol consumption, females—a group infrequently studied in the literature on blackouts—are at greater risk than males for experiencing blackouts. A woman’s tendency to black out more easily probably results from differences in how men and women metabolize alcohol. Females also may be more susceptible than males to milder forms of alcohol–induced memory impairments, even when men and women consume comparable amounts of alcohol.
Blackouts are much more common among social drinkers than previously assumed and should be viewed as a potential consequence of acute intoxication regardless of age or whether the drinker is clinically dependent on alcohol.772 colleges undergraduates about their experiences with blackouts and asked, “Have you ever awoken after a night of drinking not able to remember things that you did or places that you went?” Of the students who had ever consumed alcohol, 51 percent reported blacking out at some point in their lives, and 40 percent reported experiencing a blackout in the year before the survey. Of those who reported drinking in the 2 weeks before the survey, 9.4 percent said they blacked out during that time. The students reported learning later that they had participated in a wide range of potentially dangerous events they could not remember, including vandalism, unprotected sex, and driving.
Equal numbers of men and women reported experiencing blackouts, despite the fact that the men drank significantly more often and more heavily than the women. This outcome suggests that regardless of the amount of alcohol consumption, females—a group infrequently studied in the literature on blackouts—are at greater risk than males for experiencing blackouts. A woman’s tendency to black out more easily probably results from differences in how men and women metabolize alcohol. Females also may be more susceptible than males to milder forms of alcohol–induced memory impairments, even when men and women consume comparable amounts of alcohol.
Wernicke-Korsakoff Syndrome
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Schematic drawing of the human brain, showing regions vulnerable to alcoholism-related abnormalities.
Up to 80 percent of alcoholics, however, have a deficiency in thiamine, and some of these people will go on to develop serious brain disorders such as Wernicke–Korsakoff syndrome (WKS). WKS is a disease that consists of two separate syndromes, a short–lived and severe condition called Wernicke’s encephalopathy and a long–lasting and debilitating condition known as Korsakoff’s psychosis.
The symptoms of Wernicke’s encephalopathy include mental confusion, paralysis of the nerves that move the eyes (i.e., oculomotor disturbances), and difficulty with muscle coordination. For example, patients with Wernicke’s encephalopathy may be too confused to find their way out of a room or may not even be able to walk. Many Wernicke’s encephalopathy patients, however, do not exhibit all three of these signs and symptoms, and clinicians working with alcoholics must be aware that this disorder may be present even if the patient shows only one or two of them. In fact, studies performed after death indicate that many cases of thiamine deficiency–related encephalopathy may not be diagnosed in life because not all the “classic” signs and symptoms were present or recognized.
Approximately 80 to 90 percent of alcoholics with Wernicke’s encephalopathy also develop Korsakoff’s psychosis, a chronic and debilitating syndrome characterized by persistent learning and memory problems. Patients with Korsakoff’s psychosis are forgetful and quickly frustrated and have difficulty with walking and coordination. Although these patients have problems remembering old information (i.e., retrograde amnesia), it is their difficulty in “laying down” new information (i.e., anterograde amnesia) that is the most striking. For example, these patients can discuss in detail an event in their lives, but an hour later might not remember ever having the conversation.
TREATMENT:The cerebellum, an area of the brain responsible for coordinating movement and perhaps even some forms of learning, appears to be particularly sensitive to the effects of thiamine deficiency and is the region most frequently damaged in association with chronic alcohol consumption. Administering thiamine helps to improve brain function, especially in patients in the early stages of WKS. When damage to the brain is more severe, the course of care shifts from treatment to providing support to the patient and his or her family. Custodial care may be necessary for the 25 percent of patients who have permanent brain damage and significant loss of cognitive skills.Scientists believe that a genetic variation could be one explanation for why only some alcoholics with thiamine deficiency go on to develop severe conditions such as WKS, but additional studies are necessary to clarify how genetic variants might cause some people to be more vulnerable to WKS than others.[5]
The symptoms of Wernicke’s encephalopathy include mental confusion, paralysis of the nerves that move the eyes (i.e., oculomotor disturbances), and difficulty with muscle coordination. For example, patients with Wernicke’s encephalopathy may be too confused to find their way out of a room or may not even be able to walk. Many Wernicke’s encephalopathy patients, however, do not exhibit all three of these signs and symptoms, and clinicians working with alcoholics must be aware that this disorder may be present even if the patient shows only one or two of them. In fact, studies performed after death indicate that many cases of thiamine deficiency–related encephalopathy may not be diagnosed in life because not all the “classic” signs and symptoms were present or recognized.
Approximately 80 to 90 percent of alcoholics with Wernicke’s encephalopathy also develop Korsakoff’s psychosis, a chronic and debilitating syndrome characterized by persistent learning and memory problems. Patients with Korsakoff’s psychosis are forgetful and quickly frustrated and have difficulty with walking and coordination. Although these patients have problems remembering old information (i.e., retrograde amnesia), it is their difficulty in “laying down” new information (i.e., anterograde amnesia) that is the most striking. For example, these patients can discuss in detail an event in their lives, but an hour later might not remember ever having the conversation.
TREATMENT:The cerebellum, an area of the brain responsible for coordinating movement and perhaps even some forms of learning, appears to be particularly sensitive to the effects of thiamine deficiency and is the region most frequently damaged in association with chronic alcohol consumption. Administering thiamine helps to improve brain function, especially in patients in the early stages of WKS. When damage to the brain is more severe, the course of care shifts from treatment to providing support to the patient and his or her family. Custodial care may be necessary for the 25 percent of patients who have permanent brain damage and significant loss of cognitive skills.Scientists believe that a genetic variation could be one explanation for why only some alcoholics with thiamine deficiency go on to develop severe conditions such as WKS, but additional studies are necessary to clarify how genetic variants might cause some people to be more vulnerable to WKS than others.[5]
Alchohol and The Developing Brain
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Drinking during pregnancy can lead to a range of physical, learning, and behavioral effects in the developing brain, the most serious of which is a collection of symptoms known as fetal alcohol syndrome (FAS). Children with FAS may have distinct facial features (see illustration). FAS infants also are markedly smaller than average. Their brains may have less volume (i.e., microencephaly). And they may have fewer numbers of brain cells (i.e., neurons) or fewer neurons that are able to function correctly, leading to long–term problems in learning and behavior. [5]