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Mayo study finds controversial precursor to Alzheimer’s disease is more common in men

Men may be more likely to develop a pre-Alzheimer’s condition known as mild cognitive impairment (MCI), a Mayo Clinic study has found.

It’s not clear yet, however, what clinical value this finding will have. For MCI is a controversial diagnosis, and not all neurologists are convinced it should be used with patients.

A surprising finding

The Mayo study involved 2,050 men and women between the ages of 70 to 89 who live in Minnesota’s Olmstead County. The participants were interviewed about their memory and their medical history. They were also given several tests to evaluate their memory and other cognitive (thinking) skills. None had previously been diagnosed with dementia.

The study found that 1,969 of the participants (1,001 men and 967 women) were without dementia. Of those 329 (192 men and 137 women) — some 16 percent — had MCI, which the Mayo Clinic defines as “an intermediate stage between the expected cognitive decline of normal aging and the more pronounced decline of dementia.” (For Mayo’s full description of MCI, go here.)

The rate of MCI in the men, therefore, was 1.5 times greater than in the women.

“We were somewhat surprised by that,” Dr. Ronald Petersen, a neurologist and director of the Mayo Clinic Alzheimer’s Disease Research Center, told me last week. “There are generally more women than men with Alzheimer’s, partly because women live longer than men. One would think that if MCI was the prodromal [early] phase of the disease, you’d see the same gender distribution pattern.”

It may be, he said, that women move along the continuum from MCI to Alzheimer’s more quickly than men.

Petersen said the next step is to continue following the study’s participants to see which ones develop Alzheimer’s, and at what rate. “Most of [those with MCI] probably will,” said Petersen, “but not all of them. While MCI is, in general, a footprint for Alzheimer’s disease, it’s not an absolute one.”

Some people with MCI go on to see their memory and other cognitive problems improve, he added.

An example of medicalization?

The fact that MCI may or may not predict Alzheimer’s cast doubts upon its clinical validity, say skeptics of the condition. One of those skeptics is Dr. Peter J. Whitehouse, a neurologist and founder of the Memory and Cognition Center at Case Western Reserve University. Whitehouse sees MCI as yet another example of the medicalization of the normal aging process.

“It is an example of labeling what is a continuum of brain aging that we all go through,” he said in a phone interview.

MCI is so ill defined, he said, that an Australian researcher recently identified 48 different definitions of it currently in use.

Because no one can say with any certainty which people with MCI (under any definition) will go on to develop Alzheimer’s and which ones won’t, there is no benefit of using it in clinical practice, Whitehouse added.

He said he worries about proposals to have people undergo PET, MRI, genetic and other tests for early signs of dementia when the results may be meaningless in terms of quantifying an individual’s risk of later developing Alzheimer’s and when no cure exists.

Such testing could run as much as $10,000 per person, “and at the end of the day you have nothing important to say to them,” he said.

“If [the MCI] label is going to help you prepare, then I think it’s weak,” he added. “Alzheimer’s is so common that, frankly, we should all prepare.”

The Mayo Clinic study appears in the Sept. 7 edition of the St. Paul-based journal Neurology.

Comments (1)

  1. Submitted by Bob DeMarco on 09/12/2010 - 08:41 am.

    The Alzheimers Reading Room has clear, concise, usable news, research, insight and advice for the entire Alzheimers community.

    The website focuses on those suffering from Alzheimers disease and Dementia, Alzheimers caregivers, and the art of Alzheimers caregiving.

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