Obesity, Diabetes And Heart Risk Linked To Alzheimer's, Dementia, Cognitive Decline

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Main Category: Obesity / Weight Loss / Fitness
Also Included In: Diabetes;  Cardiovascular / Cardiology;  Alzheimer's / Dementia
Article Date: 10 Mar 2009 - 12:00 PST

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Four studies published in a leading journal this week suggest that metabolic disorders such as obesity and diabetes may share risk factors that affect the development of Alzheimer's disease, other forms of dementia and cognitive decline.

The studies are published in the March issue of Archives of Neurology, a JAMA/Archives journal and find that:

1. The more components of metabolic syndrome a woman has, the more likely she is to develop cognitive impairment
   Dr Kristine Yaffe of the University of California, San Francisco, and the San Francisco Veterans' Affairs Medical Center, and colleagues recruited nearly 5,000 women of average age 66 with no cognitive impairment and followed them for four years. Of the 10 per cent who had metabolic syndrome, 7 per cent developed cognitive impairment compared with 4 per cent who did not have metabolic syndrome. The risk of developing cognitive impairment went up for each additional metabolic syndrome component present. (Click here for more info).


2. A man who is obese in old age is more likely to have worse cognitive function
   Dr Alka M Kanaya of the University of California-San Francisco, and colleagues studied over 3,000 elderly people enrolled in the Health ABC Study. They assessed their overall body fat (adiposity) from their their body mass index, waist size, saggital diameter (from highest point of abdomen to the back), total fat, subcutaneous fat (under the skin) and visceral fat (between internal organs). Men with higher levels of body fat performed worse in cognitive function tests taken at the beginning of the study and after three, five and eight years. But no such link was found in the women.(Click here for more info).


3. Being obese in middle age, or underweight in old age puts a person at greater risk of dementia
   Dr Annette L Fitzpatrick of the University of Washington, Seattle, and colleagues followed 2,700 adults of average age 75 without dementia who reported their weight in midlife (age 50) and had their height and weight measured in late life (age 65 and over). The average follow up was 5.4 years. They found that those people who were obese in midlife (body mass index, BMI, over 30) were more likely to develop dementia than those of normal weight. However, in late life the picture was quite different. Being obese in late life appeared to protect against dementia, while being underweight (BMI under 20) put a person at increased risk, and being overweight had no effect. (Click here for more info).


4. A person with Alzheimer's disease who has a history of diabetes and higher levels of total and "bad" (LDL) cholesterol is more likely to have a faster rate of cognitive decline
   Dr Elizabeth P Helzner and colleagues at the Columbia University Medical Center, New York, studied 156 patients who were diagnosed with Alzheimer's at average age 83 and followed them for an average of 3.5 years. Over this time, those with higher LDL ("bad" cholesterol) and total cholesterol before diagnosis showed a faster decline on tests of cognitive function compared to those whose cholesterol was normal. This was the same for those who had a history of diabetes compared to those who did not. (Click here for more info).

Metabolic syndrome is a group of risk factors that predisposes a person to heart disease, diabetes, and other conditions. The risk factors include: obesity, mild glucose abnormalities, high blood pressure, and adverse changes in blood fats.

Metabolic syndrome affects about one in five people and older people more. Some studies suggest 1 in 4 people in the US have the condition.

In an accompanying review titled " Insulin Resistance May Links Metabolic and Cognitive Disorders", Dr Suzanne Craft of Veterans Administration Puget Sound Health Care System and University of Washington School of Medicine in Seattle, suggested that insulin resistance, which is when the tissues in the body stop being sensitive to the hormone that controls glucose levels, may be behind dementia and metabolic disorders like diabetes and obesity.

Craft wrote:

"Considerable progress has been made in establishing relationships among metabolic disorders and late-life dementing illnesses."

"A number of challenges must be addressed as we move forward to determine the key mechanisms underlying these associations," she concluded, while emphasizing the need to have clear definitions of both metabolic and neurological conditions.

"Future research aimed at identifying mechanisms that underlie comorbid associations will not only provide important insights into the causes and interdependencies of late-life dementias, but will also inspire novel strategies for treating and preventing these disorders," wrote Craft.

Sources: JAMA/Archives.

Written by: Catharine Paddock, PhD
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

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