We have known about the risk factors of dementia for a while, such as high blood ­pressure, obesity, diabetes, low levels of good cholesterol and sleep disorders.

But ­surprising research led by ­ University ­College London has found that these factors are ­magnified ­depending on which ethnic group you belong to.

The stunning conclusion is that eliminating those ­modifiable risk factors could theoretically prevent around 40% of dementia cases.

UCL academics studied data from English primary care records from 1997 to 2018, covering 865,674 adults in diverse ethnic groups.

Overall, 12.6% of the study group developed dementia: 16% of white people, 8.6% of South Asian people, 12.1% of Black people and 9.7% of those from other ethnic groups.

Nearly all risk factors analysed in the study were associated with dementia, with the same risk factors often conferring a higher risk of dementia in Black and South Asian people, ­particularly for cardiovascular risk. High blood pressure carries a higher risk of dementia in Black people compared to white people, while raised blood pressure, obesity, diabetes, low HDL and sleep disorders confer a higher risk of dementia in South Asian people.

Compared to the effects in white people, hypertension has 1.57 times more impact on dementia risk in South Asian people and 1.18 times more impact in Black people.

Previous research led by this study’s lead author, Dr Naaheed Mukadam (UCL Psychiatry), found that dementia rates are 22% higher among Black people in the UK compared to white people, while Black and South Asian dementia patients die younger, and sooner after diagnosis.

An earlier study by Dr Mukadam found that close to one in two cases of dementia could be preventable in low- to ­middle-income countries.

The scientists recommend dementia prevention efforts should be targeted towards people from minority ethnic groups and focused on risk factors of particular importance.

Dr Mukadam said: “Dementia is a growing burden on our ageing population, and this study adds to findings that this is disproportionately affecting some ethnic minority communities.

“Not only are some risk factors for dementia more common among ethnic minority groups, but these factors also have greater impacts on dementia risk than among the white population.

“We need more prevention efforts tailored for ethnic minority ­communities to ensure dementia prevention is equitable, helping health professionals become culturally ­sensitive and able to inform their patients about dementia risk factors.” There’s absolutely no question that more emphasis on ethnic diversity is needed.