Memory and Thinking Tests Could Predict Alzheimer's Disease 18 Years Ahead of Onset

Is it possible to predict a person’s future risk of developing Alzheimer’s disease? Yes, says a new study published in Neurology, and the prediction can be made even 18 years before it can be properly diagnosed.

A research team from Rush University Medical Center in Chicago conducted a study on 2,125 European-American and African-American individuals in Chicago aged 65 years or above. None of the seniors had clinical Alzheimer's disease when they were selected for the research.

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The individuals enrolled for the study were given tests every three years that examined their episodic memory, executive function and global cognition. Episodic memory refers to memory of certain events experienced by the person. Executive function refers to the ability to plan and carry out tasks. Cognition refers to the ability of obtaining information and understanding it.

About 21% of the participants - about 17% of European-Americans and 23% of the African-Americans - developed Alzheimer's disease during the study.

The study found that individuals who got the lowest scores in tests of episodic memory, executive function, and global cognition over an 18-year-long period were almost 10 times more likely to develop Alzheimer's disease than those with higher scores.

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Kumar B Rajan, an Indian origin scientist with Rush University Medical Center in Chicago explains that the changes in some brain function that precede symptoms of the mental disease begin decades before.

“While we cannot currently detect such changes in individuals at risk, we were able to observe them among a group of individuals who eventually developed dementia due to Alzheimer’s,” says Kumar.

The exact reason for the apparent link between low test scores and the onset of Alzheimer's disease is not known. Further studies on larger groups of patients will probably explain why these individuals are susceptible to Alzheimer’s disease.

"A general current concept is that in development of Alzheimer's disease, certain physical and biological changes precede memory and thinking impairment. If this is so, then these underlying processes may have a very long duration. Efforts to successfully prevent the disease may well require a better understanding of these processes near middle age," says Rajan.

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References:

1. Kumar B Ranjan et al. Cognitive impairment 18 years before clinical diagnosis of Alzheimer disease dementia. doi: http://dx.doi.org/10.1212/WNL.0000000000001774 Neurology 10.1212/WNL.0000000000001774

2. http://www.neurology.org/content/early/2015/06/24/WNL.0000000000001774

3. https://en.wikipedia.org/wiki/Alzheimer%27s_disease

4. http://www.alz.org/alzheimers_disease_what_is_alzheimers.asp

Source-Medindia