African Caribbeans Develop Dementia More Often, Earlier

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.