Black people more likely to develop dementia

Two recent studies have suggested that Black people are more likely to develop dementia.

However, the picture is a complex one, showing an interplay between genetic factors, underlying health conditions themselves linked to both genetics and lifestyle factors, and almost certainly, health inequality.

Health inequality: the unjust and avoidable differences in people’s health across the population and between specific population groups

The first piece of research - Incidence, age at diagnosis and survival with dementia across ethnic groups in England: A longitudinal study using electronic health records - looked at 20 years' worth of GP medical records and found that:

• Dementia incidence was higher in Black people
• South Asian and Black people with dementia had a younger age of death than White participants

Incidence: refers to the number of individuals who develop a specific disease or experience a specific health-related event during a particular time period (such as a month or year).

The second piece of research - Risk factors, ethnicity and dementia: A UK Biobank prospective cohort study of White, South Asian and Black participants - followed nearly 300,000 people who took part in the UK Biobank study for up to 14 years and found that Black participants were more likely to develop dementia than White participants, with South Asian participants having a similar risk to White participants.

This research looked at the following modifiable risk factors and the genetics for each of three ethic groups, White people, Black people, South Asian people:

• education
• hearing loss
• hypertension
• obesity
• excess alcohol consumption
• physical inactivity
• smoking
• high total cholesterol
• depression
• diabetes
• social isolation
• air pollution

Findings

They found no evidence to support the hypothesis that ethnicity modifies the association between any of the specified risk factors and dementia. So how can the difference in dementia incidence be explained?

They believe that whilst the South Asian population had a higher burden of some of the modifiable risk factors above e.g. hypertension and diabetes (than the White population), they were far less likely to carry the Apolipoprotein E allele (than the White population). So potentially, the reduced genetic risk, cancels out the modifiable risk factors.

Whilst Black populations had both a higher burden of some of the modifiable risk factors above e.g. hypertension and obesity (than the White population), and were more likely to carry the Apolipoprotein E allele (than the White population). Thus, they have twice the burden.

Apolipoprotein E allele: also known as APOE4, this is the most significant genetic risk factor for dementia. Read more here

Health inequality?

In the BBC report on this - Black people more likely to develop dementia, large study finds - Dr Naaheed Mukadam, study author and senior research fellow in psychiatry at UCL, said what lies behind a higher risk of dementia in black people was a "complex picture".
"It could be driven by genetics or the way their risks are managed," she said.
"The difference means we need greater awareness in that population that dementia is a concern - and more proactive management of risk factors like hypertension, and more health checks."

Given that we know that multiple barriers to accessing care exist, such as knowledge and awareness, as well as social-cultural barriers, such as certain subjects being taboo or people feeling unwelcome or discriminated against, this factor is incredibly important.