Men More Vulnerable to Alzheimer’s Disease, Says New Study

Tuesday, January 31, 2012

 

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New research points to surprising links between mild cognitive impairment and gender.

Men are more affected than women by a condition linked to Alzheimer's disease, according to new research at the Mayo Clinic. Researchers involved in the Mayo Clinic Study of Aging have discovered that mild cognitive impairment (MCI) affects men as well as those who only have a high school education more than women and those who have completed some higher education.

MCI: between normal forgetfulness and dementia

People with MCI are at the stage between suffering the normal forgetfulness associated with aging and developing dementia, such as that caused by Alzheimer's disease. More than 6 percent of Americans age 70 to 89 develop MCI every year.

The study, "The Incidence of MCI Differs by Subtype and is Higher in Men," which was published in the Jan. 25, 2012, issue of Neurology, the medical journal of the American Academy of Neurology, reports that 296 of the 1,450 study participants developed MCI, an incidence rate of 6.4 percent per year overall. Among men, the incidence rate was 7.2 percent, compared with 5.7 percent per year for women.

"While incidence rates for MCI have been reported previously, ours is one of the few studies designed specifically to measure the incidence of MCI and its subtypes using published criteria," said lead author Rosebud O. Roberts, M.B., Ch.B., of the Mayo Clinic Division of Epidemiology. "The statistically significant difference between incidence rates among men and women represents an important finding for those evaluating patients for MCI."

RI Hospital expert: Brian Ott, MD

GoLocalProv spoke with Brian Ott, M.D., director of The Alzheimer's Disease & Memory Disorders Center at Rhode Island Hospital, about the implications of the Mayo research for Rhode Islanders.

How many Rhode Islanders suffer from MCI... and what are the outcomes over time?

We have no data on the prevalence of MCI in Rhode Island. The prevalence of MCI among people age 70-89 in the Mayo Clinic series was 16%.  Based on an estimate of about 100,000 people in Rhode Island in this age range, one could project that we probably have at least 16,000 people in our state with MCI. MCI is generally regarded as a transitional state from normal aging to Alzheimer's disease for most people, with conversion rates to dementia varying but generally around 15% each year.  The Alzheimer's Association estimates that we have about 24,000 people with Alzheimer's disease in Rhode Island.

What are the main takeaways from this study? Are men really at a higher risk for cognitive impairment than women?

I think there are two main takeaway messages from this study.

Men may be more vulnerable than women to factors that can lead to cognitive impairment as they age, particularly those with low educational attainment.  If so, we need to learn more about such factors, since they may be reversible with appropriate treatment.  In this study, about 1/3 of the participants changed from impaired to normal, but the factors associated with this change are not described other than for being less impaired when they were diagnosed as having MCI.

MCI is generally regarded as a transitional stage on the way to development of Alzheimer's dementia, and women are more likely than men to develop Alzheimer's.  Therefore one would have expected that the incidence of MCI would have been higher in women, as was previously shown in a similar study from Germany.   It is difficult to explain why male gender being a risk for MCI may not translate to increased risk for Alzheimer's disease or dementia in general.  Further research is therefore needed to understand how men may be more resistant than women to development of dementia even though they are experiencing  mild decline in their cognitive abilities.


What about the secondary finding regarding education level in the study? What is your take on that?

Education has been shown in many studies to be a "protective" factor against development of dementia. The most popular explanation for this finding is that higher education creates more "cognitive reserve," i.e. one develops many more nerve cell connections with education that make the brain more resistant to the disease processes of degeneration.  You can think of the brain as being a massive vault of hard wired electrical connections.  The more connections you have made through education and the more complex and redundant those connections are, the more work it would take for a disease to break down enough connections to cause symptoms such as inability to form new memories.  So education may not prevent the disease, but it may delay the onset of symptoms of the disease though this mechanism.

What services are there in RI for people with MCI?

Diagnostic services and opportunities for participation in research are offered at the memory clinics at Rhode Island Hospital and Butler Hospital.  Educational information and support services are offered by the Rhode Island Alzheimer's Association Chapter.

We are currently participating in a multicenter national study called the Alzheimer's Disease Neuroimaging Initiative.  In this 5-year study we are using advanced brain imaging techniques, like PET scans that can show amyloid deposits in the brain many years before any symptoms of memory loss occur, as well as sensitive memory tests and other biological markers of early Alzheimer's disease to detect the very earliest signs of the disease in people with MCI as well as older people with no memory problems at all.  Interested people can call Michele Astphan or Santina Horowitz at the Rhode Island Hospital Alzheimer's Disease & Memory Disorders Center.  Information can also be obtained online here.

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