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Metabolic syndrome linked to dementia

Friday, November 12, 2004

JAMA 2004; 292: 237-2242

Metabolic syndrome accelerates cognitive decline in the elderly, claim clinicians in this week's issue of the Journal of the American Medical Association.

The metabolic syndrome – a clustering of at least three disorders including abdominal obesity, hypertriglyceridemia, reduced high-density lipoprotein cholesterol levels, hypertension, and hyperglycemia – has been linked to cardiovascular disease in several studies.

Previous research has also established a link between cardiovascular disease and dementia. However, data linking the metabolic syndrome and cognition are sparse.

In an attempt to find out if a link exists between the two conditions, Kristine Yaffe (University of California, San Francisco) and colleagues measured cognitive decline and the presence of the metabolic syndrome in 2632 volunteers with an average age of 74 years.

The authors write that, by the end of the 5-year study, those with metabolic syndrome were 20% more likely than those without the disorder to have cognitive impairment. This impairment was defined as a drop of at least five points on a standard cognitive test.

Interestingly, Yaffe and team found that 30% of patients who had the metabolic syndrome as well as high levels of inflammation suffered cognitive decline, compared with only 20% of volunteers who were free from both the metabolic syndrome and high inflammation.

Importantly, those with the metabolic syndrome and low levels of inflammation also had a 20% chance of cognitive impairment, implicating inflammation as a promoter of cognitive decline.

Speculating on the most likely mechanism behind the association, the scientists suggest: "The metabolic syndrome contributes to accelerated atherosclerosis that is associated with an inflammatory response and, in turn, either the atherosclerosis or inflammation or both, contribute to cognitive decline."

They add: "Future studies will need to address whether preventing the metabolic syndrome or lowering inflammation prevents cognitive impairment in elderly individuals."