Risk of dementia is higher for blacks than whites, British study finds

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A survey of data from 295,000 people in the UK pointed to a higher risk of developing dementia in black people than in white or Asian people.

The associated risk for neurodegenerative disease in individuals over age 55 was 34% to 43% higher in blacks compared to whites. The same risk was not found for other ethnicities evaluated, such as Asians.

The results were published in this Wednesday’s edition (12) of the scientific journal PLoS One. The research was carried out by scientists from the Division of Psychiatry at University College London and the Camden and Islington Fund of the British National Health Service.

To assess the risk associated with developing dementia, the scientists analyzed data from 294,162 participants aged 40 to 69 whose information was entered in the so-called UK biobank from 2006 to 2010. This information included ethnicity, education, age, gender, physical activity, previous health conditions (diabetes, hypertension, obesity, hearing loss, etc.), consumption of alcohol, cigarettes and exposure to air pollution.

Scientists also collected blood samples from participants to trace the presence of already known biomarkers for dementia that may be associated with a higher or lower risk of developing the disease. Weight and body mass index were also noted individually.

For risk assessment, the researchers selected only individuals aged 55 years or older at the time of entry into the study, as in younger people the risk is low. Age, gender, and sociodemographic factors were adjusted for all participants.

In the analyzed period, 5,972 patients developed dementia (2.03%), being 5,789 white, 79 Asian and 91 black. The so-called hazard ratio (HR) in participants who self-reported as black was 1.43 (95% confidence interval), while in participants who self-reported as Asian it was 1.09 (with 95% confidence interval). The control group for the study was self-declared white, as this was the population in which the HR was equal to 1.

When adjusting the data for all risk factors, including education, genetic predisposition, and previous health conditions, the risk in the black population was still higher than in the self-reported white population, with an HR equal to 1.34 (95% confidence interval).

The research also found a strong correlation between education and risk of developing dementia, with the lowest risk the higher the education of the analyzed group, and also the highest risk for people with higher rates of obesity, diabetes, hearing loss or hypertension.

However, in the white population, what most influenced the risk of developing dementia was smoking (HR=1.23, compared to 1.03 in blacks and 0.9 in Asians). The analysis did not find moderate to high consumption of alcohol (equivalent to equal to or less than 21 drinks per week) as a risk factor for dementia in blacks, but the fact that this consumption was higher in the white population may have influenced this result.

For Naaheed Mukadam, a psychiatrist and researcher at University College London and the first author of the study, this result is in agreement with research carried out in other countries, which showed that lifestyle habits such as cigarette and alcohol consumption are more associated with the risk of dementia in people. of white ethnicities, while chronic diseases are more associated with black populations and those with greater social vulnerability.

“The black population in our study had very low rates of smoking and excessive alcohol consumption. On the other hand, rates of diabetes, obesity, and hypertension were higher in this group compared to the white population. Even adjusting for these factors, blacks still had a higher risk for dementia, which indicates that this high risk is not explained only by the high incidence of these factors”, he explains.

According to Mukadam, another factor that may influence this risk for blacks is the high frequency of a gene considered as a marker of dementia, which appeared more in the black population studied than in whites.

“We don’t know why this allele is more common in this specific group of the black population compared to Asians and whites. If the frequency of this same gene is distributed differently in other black populations, or even in the general population, we are going to need more studies. to find out,” he says.

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