To mark World Stroke Day, Professor Pankaj Sharma, OBE, Principal Clinical Teacher at Imperial College London’s Faculty of Medicine and Consultant Neurologist at Imperial College Healthcare NHS Trust, reflects on decades of research uncovering why British South Asian populations experience stroke earlier and more severely than their White British counterparts. Through the groundbreaking BRAINS biobank, his work is revealing crucial genetic and lifestyle insights to improve prevention and outcomes.
Stroke is the third biggest killer globally, second largest cause of dementia, and the most frequent reason for disability. It consumes around 5% of the entire NHS budget. Yet these statistics are not evenly spread across different populations.
British people of South Asian heritage tend to have a worse cardiovascular profile compared to White British individuals. This is likely related to multiple factors, including poorer diets, less exercise, and delayed access to healthcare services. People from South Asia arrived in the UK in large numbers in the 1960s and 1970s. Britain is now home to one of the largest diasporas of South Asian people from the Indian subcontinent and research suggests that this population interacts more frequently with NHS services compared to equivalent White British patients.
However, in order to understand the specific needs of people of South Asian heritage, comprehensive and detailed data are needed, particularly since most of our understanding about stroke and related cardiovascular disease is based on large prospective studies of (often middle-class) White individuals, typically from the United States. Realising the lack of quality data, I set out around 15 years ago to establish a biobank for stroke in South Asian people. It started slowly but rapidly expanded with recruitment taking place across England, India, Qatar and Sri Lanka. Its unique focus on ethnic minorities attracted multimillion dollar funding. The BioRepository of DNA in Stroke (BRAINS) has now become one of the largest such biobanks in the world.
Analysis from the BRAINS study has demonstrated that British South Asian people experience ischaemic (clot) stroke approximately nine years earlier than their White British counterparts. Moreover, South Asian people residing in India experience stroke nearly nineteen years earlier. We show that these stark differences are not simply related to greater comorbidity but to ethnicity itself. My group further showed that these differences are not isolated to stroke but extend also to ischaemic heart disease with South Asian patients showing a higher prevalence than White patients. These results have important public health implications, arguing for a more focused approach to education and treatment.
One of the major questions we wanted to answer from the outset was whether there are genetic differences contributing to the increased burden of stroke in people of South Asian heritage. Our earlier work suggested that different ancestral populations had greater/lesser genetic liability for cardiovascular disease such as heart disease and stroke. However, our conclusions were based on relatively small studies. With BRAINS we now have the opportunity to undertake one of the largest genome-wide studies of stroke in South Asian people. That work is ongoing, and the first results should be available in the next year.
Stroke is a devastating disease affecting not just the patient but also their carers, relatives and friends. Non-white populations are particularly affected, but our ongoing work is providing important insights into why this is the case. Insights we hope will lead to better outcomes and, importantly, fewer strokes in the future.