Dementia is a disease that is not just linked to the overweight and obese people; but occurs in the skinny and underweight too.

In the May 2008 issue of Obesity Reviews, a study has been published that shows that people who are either obese or underweight are likely to face greater risks of dementia. Researchers in Johns Hopkins Bloomberg School of Public Health in Baltimore have instituted that obese people have an increased risk of 80 percent to the Alzheimer’s disease when compared to those with a normal weight.

The study has found that the underweight have 36 % greater chances of developing such cognitive disorders.

Researchers in the United States conducted an in-depth study giving a comprehensive review of 10 international studies published since 1995 which covered around 37,000 people, which included 2,534 people suffering various forms of dementia. In the beginning of the study, the people targeted were aged between 40 to 80 years, with a follow-up period which ranged from 3 to 36 years.

The review encloses studies from different places like the US, France, Finland, Sweden and Japan. The 7 studies which were published between the period of 2003 and 2007 with a follow-up period of 5 years included a refined meta-analysis.

Various types of dementia included had a definite reference to Alzheimer’s disease and to vascular dementia wherein some areas of the brain do not function as the blood vessels which are supplied to them get damaged because of high blood pressure or other heart disease.

Dr Youfa Wang, Associate Professor of International Health and Epidemiology at Johns Hopkins Bloomberg School of Public Health, Baltimore said, “Our meta-analysis showed that obesity increased the relative risk of dementia, for both sexes, by an average of 42 per cent when compared with normal weight. And being underweight increased the risk by 36 per cent.”

He added, “But when we looked specifically at Alzheimer’s Disease, the increased risk posed by obesity was 80 per cent. The increased risk for people with vascular dementia was 73 per cent.The risks were greater in studies where sufferers developed Alzheimer’s Disease or vascular dementia before the age of 60 or in studies with follow-up periods of more than 10 years. We also found that obesity was more likely to be a risk factor for women when it came to developing Alzheimer’s Disease and for men when it came to vascular dementia.”

The analysis has even showed that central obesity has an increased risk of vascular dementia but not Alzheimer’s disease. The extra fat around the midsection of the body is known as Central Obesity. Thus this kind of extra fat surrounding the belly (stomach) leads to high cholesterol and an increased risk in heart attack.

Alzheimer’s disease progresses slowly in the brain and is generally a cause of dementia in people aged 65 and older. Around 5 million people in United States are living with this condition, according to the Alzheimer’s Association.

Two-thirds of adults are overweight or obese, according to the National Institutes of Health.

To keep up with the current standard of living a healthier lifestyle, it is necessary to reduce obesity rates and to prevent the progression of Alzheimer’s disease.