Heavy alcohol use, like Alzheimer's, is associated with dementia. Because alcohol's impact on cognitive function is similar to that observed with Alzheimer's, some have suggested that alcoholism may either be a risk factor for developing Alzheimer's or may accelerate its course. To date, researchers have not found clear evidence of this.
Background
According to the National Institute on Alcohol Abuse and Alcoholism (NIAAA), people who drink heavily over long periods show serious and persistent changes in cognitive function. The nature and extent of these brain deficits vary with personal characteristics and the pattern of alcohol use.
Alzheimer's, according to the Alzheimer's Association, is the leading cause of dementia in the U.S. It is characterized by a progressive loss of memory and other cognitive changes. Because a loss in cognitive functioning is common to both, and because some of the same neurochemical pathways are affected, some believe alcoholism is associated with Alzheimer's.
Brain Atrophy and Cognition
Alcoholism and Alzheimer's are characterized by changes in cognitive function, brain disorders and brain chemistry. The impact of heavy alcohol consumption on the brain and cognitive functioning is evident both in the intermediate and long term. Brain tissue shrinks or atrophies, and gross comparisons of the brains of alcoholics with those of persons with Alzheimer's show remarkable similarities.
Closer examinations, however, suggests these similarities may be superficial. Research cited by the NIAAA indicates neural damage associated with heavy alcohol use differs from that of Alzheimer's. Not only did the brains of heavy drinkers not show significant brain cell destruction compared to controls, but brain atrophy decreased with abstinence. In contrast, Alzheimer's has a characteristic neural pathology characterized by plaques, microscopic protein and neuron deposits between the neurons; tangles, clumps of a protein inside the neurons; a loss of neuronal connections and brain tissue inflammation.
In addition, although both alcoholics and persons with Alzheimer's show cognitive impairments, those with alcohol-related cognitive impairments differ in that many individuals show at least some improvement in brain structure and functioning within a year of abstinence. In contrast, Alzheimer's is progressive and irreversible.
Brain Chemistry
The closest link between alcohol and Alzheimer's is, perhaps, at the level of brain chemistry. Both adversely affect the brain's cholinergic system that, among other functions, is associated with memory. Perhaps, heavy alcohol use acts as a trigger for Alzheimer's, aggravates Alzheimer's cognitive impairments or accelerates its progress. The evidence, however, is unclear.
Research Challenges
Studying the impact of heavy alcohol use and Alzheimer's is difficult. Reasons include diagnosing either condition is imprecise; there are no direct measures of the neurochemical impacts on brain function; and the changes in the brain related to heavy alcohol use is likely both direct and indirect.
Heavy alcohol users also tend to have poor nutrition, a higher incidence of stroke and a higher incidence of tobacco use, which itself is a risk factor for cognitive functioning.
Moderate Alcohol Consumption
Underscoring the complexity of alcohol's impact, several studies show light-to-moderate alcohol use may be beneficial in reducing the risk of Alzheimer's, perhaps by lowering the risk of vascular disease.
References
- NIAAA: Alcohol Use and the Risk of Developing Alzheimer's Disease: Suzanne L. Tyas, Ph.D.: 2001.
- NIAAA: Alcohol's Damaging Effects on the Brain: October 2004.
- "Age and Aging": Alcohol, Dementia and Cognitive Decline In the Elderly: A Systematic Review: Ruth Peters et al.: 2008.
- "The Lancet": Alcohol Consumption and Risk of Dementia: The Rotterdam Study: Annemieke Ruitenberg et al.: January 2002.
- "Age and Aging": Alcohol for the Older Person---Friend or Foe?: Edmond Chu: 2008.
