Ethnicity and the effect of potentially modifiable risk factors on dementia

By Dr. Sushama R. Chaphalkar, PhD.Reviewed by Lily Ramsey, LLMOct 12 2023

In a recent study published in the PLOS ONE Journal, researchers investigated how the effects of potentially modifiable risk factors on dementia vary among people of South Asian, Black, and White ethnicities.

They found that in White people, the impact of obesity, high-density lipoprotein (HDL) levels, hypertension, diabetes, and sleep disorders on dementia is lower than in South Asian people. Further, the impact of hypertension on dementia was found to be greater in the Black people than in the White.

Study: South Asian, Black and White ethnicity and the effect of potentially modifiable risk factors for dementia: A study in English electronic health records. Image Credit: Orawan Pattarawimonchai/Shutterstock.com

Background

Dementia affects about 50 million people worldwide, estimated to increase rapidly as the global population ages. Several risk factors are known to be associated with an increased risk of dementia, including obesity, hypertension, and diabetes.

Modifiable risk factors are particularly of interest to researchers as they could, in theory, help reduce the prevalence of dementia by 40%.

Studies have shown an association between modifiable risk factors of various conditions and the ethnicity of individuals. However, most previous studies investigating the potential association between ethnicity and the risk factors of dementia have been conducted in the European population.

Therefore, the present study aimed to compare the impact of potentially modifiable risk factors on dementia risk in South Asian, Black, and White populations using electronic health records.

About the study

An anonymized dataset of electronic health records obtained from the Clinical Practice Research Datalink (CPRD) was used in the study, along with a research resource named CALIBER, linking primary care records with hospital episode statistics (HES) and mortality statistics.

The study included adults aged 65 years and above with no prior diagnosis of dementia. The researchers identified potentially modifiable risk factors for dementia, including hypertension, obesity, hearing loss, diabetes, smoking, excessive alcohol consumption, dyslipidemia, low HDL, high LDL, sleep disorders, and traumatic brain injury.

Further, they assessed their impact on dementia risk in different ethnic groups. Hazard ratios (HRs) for dementia were estimated in the study using Cox proportional hazards models, adjusting for baseline age, sex, and index of multiple deprivation (IMD), and accounting for clustering by primary care practice.

Results and discussion

Out of 1,189,090 participants included in the study, 830,541 were White, 13,082 were South Asian, 9,166 were Black, and 13,860 were of other ethnicities. The complete case analysis was performed on data involving 865,674 people and 8,479,973 person-years of follow-up. About 12.6% of the whole population developed dementia.

The findings suggest that compared to White people, those with South Asian ethnicity have statistically significant interaction terms for hypertension (HR 1.57, p<0.0001), low HDL (HR 1.21, p = 0.049), obesity (HR 1.19, p = 0.04), sleep disorders (HR 1.18, p = 0.002), and diabetes (HR 1.22, p = 0.001).

Further, as per the study, Black people with hypertension had an increased risk of dementia (HR 1.18, p = 0.029) compared to White people. Interestingly, a decreased risk of dementia was observed in Black people with higher low-density lipoprotein (LDL) (HR 0.81, p = 0.005) compared to White people.

Diabetes was also associated with an increased risk of dementia in all ethnic groups, especially South Asians (HR 1.89). Smoking and alcohol consumption were associated with a lower risk of dementia in White individuals but not in South Asian or Black individuals.

The study also found that South Asian and Black individuals had higher levels of cardiovascular risk factors, particularly diabetes, compared to White individuals. The findings suggest that hypertension and diabetes are important risk factors for dementia in all ethnic groups, with the highest risk observed in South Asian individuals.

The study's strengths include its large sample size, broadly representing the general population, where individuals could be followed until death. The results highlight the utility of electronic health records as a valuable data source that can be employed to study modifiable risk factors and develop targeted interventions to prevent or delay the onset of dementia.

However, as a limitation, the study does not include information on other reported risk factors for dementia, such as individual-level education, social isolation, air pollution, and physical activity.

Conclusion

The findings of this study provide important insights into the impact of potentially modifiable risk factors on dementia risk in South Asian, Black, and White individuals and highlight the need for targeted interventions to address these risk factors.

These results can potentially aid the development of public health policy and clinical practice to reduce the risk of dementia in different ethnic groups.