Consequences of Intoxication on Brain Structure & Function

Structural damage to the brain resulting from chronic alcohol abuse can be observed in different ways:Results of autopsy show that patients with a history of chronic alcohol abuse have smaller, less massive, and more shrunken brains than nonalcoholic adults of the same age and gender.¹

• The findings of brain imaging techniques, such as CT scans  consistently show an association between heavy drinking and physical brain damage, even in the absence of chronic liver disease or dementia.

• Brain shrinking is especially extensive in the cortex of the frontal lobe² - the location of higher cognitive faculties.

• The vulnerability to this frontal lobe shrinkage increases with age.³  After 40 some of the changes my be irreversible [see below]. 

• Repeated imaging of a group of alcoholics who continued drinking over  a 5-year period showed progressive brain shrinkage that significantly exceeded normal age-related shrinkage.  Moreover, the rate of shrinkage correlated with the amount of alcohol consumed.

The relationship between alcohol consumption and deterioration in brain structure and function is not simple.  Measures such as average quantity consumed, or even total quantity consumed over a year, do not predict the ultimate extent of brain damage.

The best predictor of alcohol related impairment is: maximum quantity consumed at one time, along with the frequency of drinking that quantity. In addition to the toxic effects of frequent high levels of alcohol intake, alcohol related diseases and head injuries (due to falls, fights, motor vehicle accidents, etc.) also contribute. 

Although changes in brain structure may be gradual, performance deficits appear abruptly.  The individual often appears more capable than is actually the case, because existing verbal abilities are among the few faculties that are relatively unimpaired by chronic alcohol abuse.

The Pattern of Recovery

Despite the grim realities described above, the situation is not hopeless: With abstinence there is functional and structural recovery!  Predictably cognitive functions and motor coordination improve, at least partially, within 3 or 4 weeks of abstinence; cerebral atrophy reverses after the first few months of sobriety.⁵

• Indications of structural pathology often disappear completely with long-term abstinence.⁶ 

• Hyper-excitability of the central nervous system persists during the first several months of sobriety and then normalizes.⁷

• Frontal lobe blood flow continues to increase with abstinence, returning to approximately normal levels within 4 years.⁸ 

• In general, skills that require novel, complex, and rapid information processing take longest to recover.  New verbal learning is among the first to recover.  Visual-spatial abilities, abstraction, problem solving, and short-term memory, are the slowest to recover.  There may be persistent impairment in these domains, particularly among older alcoholics [over 40].   However, even this population may show considerable recovery with prolonged abstinence.9

• Withdrawal symptoms are themselves dangerous.

  • About 15% of alcoholics experience seizures during withdrawals, and the likelihood of having such seizures, as well as their severity, increases with the number of past withdrawal episodes.  The seizures are correlated with shrinkage of both frontal lobes, but it is not known whether the seizures are a cause or an effect of the structural changes.¹⁰ Next page >>

Footnotes:

1. Rosenbloom, M. etal. Alcohol Health Research World., 19, 266-272, 1995

2. Pfefferbaum, A. etal. Alcohol Clinical and Experimental Research, 21, 521-529, 1997

3. Ibid.

4. Pfefferbaum, A. etal. Archives of General Psychiatry. 56, 905-912, 1998

5. Oscar-Berman, A. Alcohol Health Research World., 21, 65-75, 1997

6. Neuropsychology of Alcoholism - Parsons etal. 1987

7. Ibid.

8. Gansier D. etal.  Journal of studies of Alcohol, 61, 32-37. 2000

9. Neuropsychology of Alcoholism - Parsons etal. 1987

10. Sullivan, E. etal. Alcohol Clinical and Experimental Research, 20,   348-354, 1996