Chicago, United States — Scientists had been saying Alzheimer’s begins in a patient at least two decades before it is detected by doctors. Now the degenerative disease can be predicted 18 years before it gets detected with technology used so far. Instead of physical tests, it is possible to detect it with simple tests on errors on memory and thinking tests, they say.
“The changes in thinking and memory that precede obvious symptoms of Alzheimer’s disease begin decades before,” said study author Kumar B Rajan, an Indian-origin scientist with Rush University Medical Centre in Chicago.
“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,” Kumar said.
For those diagnosed 13 to 18 years after the test, each unit lower in the test score corresponded to an 85% higher risk of the disease.
He added that while scientists can’t now detect such changes in individuals at risk, they were able to observe them among a group of individuals who eventually developed dementia due to Alzheimer’s.
The study involved more than 2,000 black and white people from Chicago. The participants were an average age of 73. They took mental skills tests every three years over a almost two-decade span, and it turns out that those who scored low on the tests had a greater chance of being diagnosed with Alzheimer’s.
During the study period, 23 percent of the black people and 17 percent of the white people developed Alzheimer’s. As an Alzheimer’s Association board member, I have seen the toll Alzheimer’s disease takes on so many Michigan families, and understand that without research, there can be no prevention, no new treatments and no cure. These odds increased as the scores dropped below average, the researchers found.
According to the Alzheimer’s Association, Alzheimer’s disease is the sixth biggest reason of death in America.
For the study, 2,125 European-American and African-American people from Chicago with an average age of 73 without Alzheimer’s disease were given tests of memory and thinking skills every three years for 18 years.
Twenty-three per cent of African-Americans and 17 per cent of European-Americans developed Alzheimer’s disease during the study.
Those who scored lower overall on the memory and thinking tests had an increased risk of developing the disease.
During the first year of the study, people with lower test scores were about 10 times more likely to be diagnosed with Alzheimer’s disease than people with higher scores, with the odds increasing by 10 for every standard deviation that the score was lower than the average.
Based on tests completed 13 to 18 years before the final assessments took place, one unit lower in performance of the standardised cognitive test score was associated with an 85 per cent greater risk (relative risk of 1.85) of future dementia.
“A general current concept is that in development of Alzheimer’s disease, certain physical and biologic changes precede memory and thinking impairment. If this is so, then these underlying processes may have a very long duration,” Kumar said.
“Efforts to successfully prevent the disease may well require a better understanding of these processes near middle age,” Kumar said.
Approximately 24 million people worldwide have dementia of which the majority (~60%) is due to Alzheimer’s.
Clinical signs of Alzheimer’s disease are characterized by progressive cognitive deterioration, together with declining activities of daily living and by neuropsychiatric symptoms or behavioral changes.
The most striking early symptom is memory loss (amnesia), usually manifest as minor forgetfulness that becomes steadily denser with illness progression, with relative preservation of older memories.
It is the most common type of dementia.
Plaques which contain misfolded peptides called amyloid beta (Aβ) are formed in the brain many years before the clinical signs of Alzheimer’s are observed.
Together, these plaques and neurofibrillary tangles form the pathological hallmarks of the disease.
These features can only be discovered at autopsy and help to confirm the clinical diagnosis.
Medications can help reduce the symptoms of the disease, but they cannot change the course of the underlying pathology.
The ultimate cause of Alzheimer’s is unknown.
Genetic factors are clearly indicated as evidenced by dominant mutations in three different genes have been identified that account for the small number of cases of familial, early-onset AD.
For the more common form of late onset AD (LOAD), ApoE is the only clearly established susceptibility gene.
All four genes can contain mutations or variants that confer increased risk for AD, but account for only 30% of the genetic picture of AD.
These four genes have in common the fact that mutations in each lead to the excessive accumulation in the brain of Aβ, the main component of the senile plaques that litter the brains of AD patients.