According to researchers at the Columbia University Medical Center in New York, high levels of education may help ward off Alzheimer’s disease, but they also speed up its progression once the disease has developed.
The findings are based on 312 New Yorkers aged 65 and older, who were diagnosed with Alzheimer’s disease and monitored for a period of over 5 years.
Alzheimer's disease, is one of the main causes of dementia in the elderly, and although it manifests itself later in people who are well educated, once it does appear it's progression is speedier.
Lead researcher Dr Nikolaos Scarmeas, monitored the progression of the illness in 312 people with a wide ability range from illiterates to highly educated patients.
All the patients underwent around four neurological assessments, each of which comprised a dozen separate tests of brain function and were then followed for a period of five years.
Overall mental agility declined every year among all the patients, but each additional year of education equated to an additional 0.3 per cent deterioration.
The level of this drop off was particularly evident in the speed of thought processes and memory.
The researchers also examined other factors, independent of age and mental ability at diagnosis, such as high blood pressure, depression, vascular disease and age, that could affect brain function and have an impact on the disease.
Scarmeas says one of the possible explanations for the finding is the theory of ‘cognitive reserve'.
This theory suggests that the brain’s ability to cope with Alzheimer’s disease varies from person to person, but the amount of nerve connections (neurons) and information hubs (synapses) are likely to be more numerous in people who are highly educated.
Alternatively, even if the quantity of neurons and synapses is no different, the synapses are likely to be more efficient and/or the alternative circuitry is likely to be operating in those who are highly educated.
The authors say they could find no other plausible explanation why people with higher brain skills and function seem more able to delay the onset of illness and its symptoms.
Analysts estimate as many as 12 million people worldwide suffer from Alzheimer's disease and predict that the number will balloon as the population ages.
There is at present no cure for this distressing progressive illness, where people lose their memory and mental ability, but drug treatments appear to slow the early progression of the disorder.
Scarmeas says people with a higher education or higher cognitive reserve have brains which develop the decreased mental agility of Alzheimer disease later, because it can “tolerate” changes for longer.
But the subsequent impact is likely to be greater than it would be in less educated brains, because of the higher levels of accumulated damage.
The research is published in the Journal of Neurology, Neurosurgery and Psychiatry.