African Caribbeans Develop Dementia More Often, Earlier

Fran Lowry

June 08, 2011

June 8, 2011 — Dementia is more common, and develops sooner in older African Caribbean people compared with white people, according to new research published online June 9 in the British Journal of Psychiatry.

"These are people who came to the UK in the 1950s and 1960s and are now aging and reaching their 70s and 80s. There may be quite a large number of Caribbean people who may be developing dementia fairly soon, and the medical profession needs to be aware of this and be prepared to look for it and refer people to specialists, even if they are a bit younger," lead researcher Simon Adelman, PhD, from University College London, United Kingdom, told Medscape Medical News.

Dr. Adelman said he and others had noticed a high degree of dementia among the African Caribbean population living in London. This prompted him and his team to do a larger study to determine the prevalence of dementia in older people of African Caribbean descent, compared with their white, United Kingdom–born peers.

The investigators studied 436 people older than 60 years living in the north London borough of Haringey. Of these, 218 had migrated to the United Kingdom from a Caribbean island or Guyana. The remaining 218 participants were white and had been born in the United Kingdom.

No Similar Increase in Black Africans

All participants were screened for cognitive impairment. Those who screened positive underwent further testing, via a standardized diagnostic interview, to see if they met the full diagnostic criteria for dementia.

Dr. Simon Adelman

After correcting for age and socioeconomic status, the researchers found that the prevalence of dementia was significantly higher in the African Caribbean group — 9.6% (21 of 218) — than in the white group — 6.9% (15 of 218) — (odds ratio, 3.1; 95% confidence interval, 1.3-7.3; P = .012).

In addition, people of African Caribbean descent with dementia were nearly 8 years younger than those in the white group. Their mean age was 79.1 years, compared with 86.9 years for whites.

Of the 36 dementia cases, 25 (69%) were Alzheimer's disease, and 10 (28%) were vascular dementia. Of the 10 people with vascular dementia, 9 were from the African Caribbean population.

"My study wasn't big enough to prove anything one way or the other, but we know that high blood pressure is a risk factor for all types of dementia, and this population has a very high prevalence of high blood pressure that is often untreated or poorly treated, and we think this might be a contributory factor," Dr. Adelman said in an interview.

The same is true for African Americans, who have an increased prevalence of dementia compared with their white counterparts, he said. However, black Africans do not have a similar increase in dementia.

"There could be a genetic component interacting with diet and high blood pressure and other vascular risk factors, such as diabetes, which increase the risk of heart disease and dementia," he said.

Lifestyle Changes Warranted

Richard Isaacson, MD, from the University of Miami Miller School of Medicine in Florida, said the study confirms past research but in a different and very specific population.

"It's an excellent study. As to why they have more dementia, that's the million dollar question," Dr. Isaacson told Medscape Medical News.

"It seems to me that African Caribbean individuals may have a higher likelihood of vascular risk factors," he said, echoing Dr. Adelman. "Things like high blood pressure, high cholesterol, diabetes. These medical conditions will increase the likelihood of developing Alzheimer's disease sooner and more severely."

Dr. Adelman, a neurologist who treats Alzheimer's patients, said the study underscores the importance of making lifestyle changes, including taking plenty of exercise and eating the right food, early in life.

"I have a family history of Alzheimer's disease, and I take a very aggressive approach to treating and possibly preventing Alzheimer's or delaying the onset of Alzheimer's," he said.

"I put my patients on a comprehensive diet plan, with low carbohydrates, increased antioxidents, and lean meats, especially fish, because eating foods that have a high glycemic index can cause the pancreas to secrete more insulin and that can cause inflammation of the brain," he said.

He believes that longitudinal research is needed, but in the meantime, it would be prudent for people who are part of at-risk populations to make healthy lifestyle changes, the sooner the better.

Dr. Adelman and Dr. Isaacson have disclosed no relevant financial relationships.

Br J Psychiatry. Published online June 9, 2011.

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