Risk of Dementia Linked to Metabolic Syndrome

Summary
There has been conflicting evidence regarding the link between metabolic syndrome and age-related dementia or memory loss. Metabolic syndrome involves symptoms of obesity, diabetes, high blood cholesterol and high blood pressure. It is known that this condition increases the risk of heart disease. However, the link between this condition and dementia is not clearly defined. A study was conducted in France to understand this association better. The results showed that those with metabolic syndrome are at a higher risk of developing dementia but not at a higher risk of developing Alzheimer’s disease.

Introduction
Dementia is the most severe form of pathological brain aging, defined by developing both memory disorders and deficiency in at least one other cognitive function. It is noted that 18 percent of elderly people over the age of 75 years have dementia. Of these, 50 to 60 percent of cases are of Alzheimer’s disease and 40 to 50 percent are of vascular dementia (dementia caused due to reduced blood flow to the brain). Metabolic syndrome is associated with an escalated danger of heart disease. Detection of metabolic syndrome and its early management help to prevent heart disease. However, if it is established that this condition is associated with dementia as well, similar preventive approaches could be devised. This study sought to explore a link between metabolic syndrome and dementia.

Methodology
•    The study involved a total of 7,087 people aged over 65 years. The population was followed over four years.
•    The participants were subjected to a three-stage test by neuropsychologists and neurologists for the presence of dementia and Alzheimer’s disease.
•    Parameters for metabolic syndrome like blood sugar, blood cholesterol, waist circumference, weight, blood pressure etc. were recorded.
•    Several interviews were conducted to record other factors like age, gender, educational qualification etc.

Results
•    Results from analysis showed that 15.8 percent of the participants had metabolic syndrome. Further, metabolic syndrome amplified the threat of vascular dementia specifically, whereas it had no effect on Alzheimer’s disease or on general dementia during the four years of observation.
•    Of all the parameters of lipid profile or cholesterol, a high triglyceride level was associated with high incidence of vascular dementia.
•    Higher waist girth corresponded to lower risk of Alzheimer’s disease.
•    Of all the factors, presence of diabetes was significantly linked to dementia.

Next steps/shortcomings
The authors agree that since all of the “oldest elderly” participants with metabolic syndrome did not survive for assessment of cognitive decline; there may be some differences in actual results from those obtained. Also, they agree that “subjects with metabolic syndrome are more likely to die from cardiovascular disease before developing dementia”. Further studies that explore the various reasons for death in people with metabolic syndrome are warranted.

Conclusion
An elderly person with high triglyceride levels and/or diabetes is at a higher risk of developing vascular dementia. The results of this study highlight the necessity for prompt detection and management of high triglyceride levels and diabetes in the elderly, to push back the beginning of “clinical dementia.” This study, however, should be interpreted with caution. The authors suggest that “metabolic syndrome as a whole does not seem to have any added value regarding dementia risk in this population.” Thus further studies that measure the exact level of association between specific parameters like triglycerides and diabetes with dementia may explain the link with dementia more clearly.

For More Information:
Metabolic Syndrome and Risk for Incident Alzheimer’s Disease or Vascular Dementia
Publication Journal: Diabetes Care, January 2009
By Christelle Raffaitin, MD; Christophe Tzourio, PhD; University Hospital of Bordeaux, Pessac, France; Bordeaux University, Bordeaux, France and Institut National de la Santé et de la Recherche Medicalé (INSERM), Bordeaux, France and INSERM, Paris, France

*FYI Living Lab Reports Are Summaries of the Original Research.
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