Posts Tagged ‘Positron emission tomography’

Early Testing For Alzheimer’s

March 20, 2013

Alzheimer’s disease often progresses slowly. In the early stages some level of mild cognitive impairment is experienced, but life proceeds as normal. Not everyone who experiences this mild cognitive impairment will progress into Alzheimer’s. They have a twelve percent chance of developing it each year. Some will never develop dementia or will develop it from causes other than Alzheimer’s disease.1

Substantial effort has gone into developing tests to identify those with mild cognitive impairment who will progress into Alzheimer’s. This is difficult as a definite diagnosis awaits finding the amyloid plaques and neurofibril tangles. Positron emission tomography (PET) scans have been done to search for amyloid plaques in the brain that may begin to appear before symptoms manifest themselves. Research has found that healthy people with these plaques in their brains are more likely to develop Alzheimer’s related dementia later in life. However, it should be remembered that although these plaques and tangles might be a necessary condition for Alzheimer’s, they are not a sufficient condition. They have been found in autopsies of people who never exhibited any symptoms. The notion is that they had a cognitive reserve that protected them from this damage.

Tests can employ PET scans and/or Magnetic Resonance Imaging (MRI) scans along with analyses of brain fluid. I have seen no data regarding the accuracy of these tests with respect to hits (correct diagnosis) versus false alarms (incorrectly diagnosing progression into Alzheimer’s). Moreover, none of the current tests can help determine whether a person with early signs will progress quickly to dementia or continue to live normally for years.2

MRI’s have been successful in treating a condition that is frequently been misdiagnosed as Alzheimer’s (See the healthymemory blog post, “A Treatable Condition Misdiagnosed as Alzheimer’s). The condition is Normal Pressure Hydrocephalus and occurs when the cerebrospinal fluid that surrounds the brain is not re-absorped. It is estimated that 5% of the people diagnosed with dementia have this condition. Unlike Alzheimer’s, this condition can be corrected.

It is somewhat ironic that early testing for Alzheimer’s can be beneficial for the diagnoses of conditions other than Alzheimer’s. Currently Alzheimer’s cannot be cured. Drugs can slow the progression of the disease, but one should consider, is this simply prolonging the agony of the sufferer? When there are opportunities for participating in a test of a new treatment, one can volunteer in the spirit of contributing to science and the development of a possible cure, but realizing that there will likely be adverse events and the likelihood of a personal cure is quite low.

There is some evidence that people can actually reduce their risk of dementia by quitting smoking, living a heart-healthy lifestyle, and treating any diabetes or hypertension that might be present. The healthymemory blog would add being both cognitively and physically active; to continue to grow cognitively, and to build and maintain social relationships. Most healthymemory blog posts address these topics. I would hope that they all make, at least, some small contribution to cognitive growth.

1Wolfe, S.M. (ed) (2013) Early Testing for Alzheimer’s. Public Citizen Health Letter, February, Vol 29, No. 2. 4-5.

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