The most common risk factors for dementia appear to have a more pronounced effect in black and Asian people, a study suggests, prompting calls for greater efforts to tackle health inequalities.
The number of adults living with dementia worldwide is on course to nearly triple to 153 million by 2050. Experts say the disease presents a major and rapidly growing threat to future health and social care systems in every community, country and continent.
Researchers have long known that some of the biggest risk factors for dementia, such as high blood pressure and diabetes, are more common in ethnic minorities.
New research suggests that not only are some risk factors more common in ethnic minorities, they also have a greater impact on their risk of developing the disease compared with white people.
The study, published in the journal Plos One, did not establish why. But researchers said it appeared the impact of risk factors such as diabetes and obesity were “magnified” among some ethnic groups.
A team led by Naaheed Mukadam, of University College London, studied the relationship between risk factors and dementia using health data for 865,674 adults in England between 1997 and 2018.
The research team found 12.6% of the cohort developed dementia. About 16% were white, 8.6% were south Asian, 12.1% were black and 9.7% were from other minority ethnic groups.
They assessed risk factors associated with dementia among the patients, including obesity, diabetes, sleep disorders, high blood pressure and dyslipidemia – an imbalance of lipids that can cause heart disease.
High blood pressure was associated with a higher risk of dementia in black people compared with white people, while south Asian people there was a higher risk associated with sleep disorders, diabetes, low HDL cholesterol and high blood pressure.
Compared with white patients, high blood pressure had 1.57 times more impact on dementia risk in south Asian people and 1.18 times more impact in black people, the researchers said.
The team said their research could explain “previous findings of greater susceptibility, earlier age of dementia onset and shorter survival after dementia diagnosis in minority ethnic groups”.
The authors added: “We found that not only are some risk factors for dementia more common in minority ethnic groups but that the impact of some of these risk factors is even greater than in the white population. So we need tailored dementia prevention, taking into account ethnicity and risk-factor profile to ensure dementia prevention is equitable.”
David Thomas, the head of policy at Alzheimer’s Research UK, said: “It’s a shocking truth that people from ethnic minorities face an increased risk of a number of health conditions, and this impacts their ability to live a healthy life. Recent research has shown that dementia is no exception – people from south Asian and black communities appear to be more likely to die from dementia, and at a younger age too.
“These latest findings suggest one reason why: the impact of risk factors like high blood pressure in increasing an individual’s risk of dementia appears greater in both south Asian and black communities.
“It will be important to understand why this effect is greater, as doing so would open up an enormous opportunity to reduce the personal and societal impact of this heart-breaking condition. But this is not just a public health problem, it is a political problem too. We need a national cross-government prevention strategy that tackles health inequalities.”
Meanwhile, the findings of a second study, also conducted by UCL, suggest that people with early Alzheimer’s disease, the most common cause of dementia, have difficulty turning when walking.
The small study, involving about 100 people and published in Current Biology, found those with early Alzheimer’s consistently overestimated their turns and had a greater variability in their sense of direction.
Sian Gregory, of the Alzheimer’s Society, said problems with navigation were thought to be some of the earliest noticeable changes of the disease, so the research provided “valuable insight”.
