People living with two or more long-term health conditions are more likely to have poorer brain health, according to a new study by researchers at Oxford Population Health. The risk of poorer brain health was more pronounced in people with cardiometabolic health conditions such as high blood pressure, high cholesterol levels, and diabetes. The study is published in The Journal of Prevention of Alzheimer’s Disease.
One in three people worldwide are living with two or more long-term health conditions, known as multimorbidity. The risk of multimorbidity increases with age and is thought to affect more than half of the global population aged 60 years and over. There is growing evidence that multimorbidity may further increase the risk of poor brain health, based on neuroimaging and cognitive outcomes. However, many of these studies have not looked at specific combinations or ‘clusters’ of related conditions.
Dementia has a long preclinical phase, during which neurodegenerative and cognitive changes begin to occur well before a formal diagnosis. Understanding the relationship between clusters of related conditions and their effect on brain health and cognitive decline is therefore important for understanding how they might affect future risk of dementia.
In this study, the researchers investigated whether multimorbidity was associated with poorer brain health in 43,160 participants in UK Biobank. Each of the participants underwent an MRI brain scan, provided information about their health and lifestyles, had physical measurements and blood samples taken, and took cognitive function tests. People who had self-reported a pre-existing neurological condition were excluded from the study.
Key findings:
- 14,339 participants in the study had multimorbidity. Among the participants without multimorbidity, 16,344 did not have any long-term health conditions and 12,477 had one long-term health condition;
- Participants with multimorbidity were more likely to be older, female, have lower educational qualifications, and have a lower socio-economic status;
- Multimorbidity was associated with poorer brain health and having a higher number of conditions was linked to progressively worse brain health;
- Cardiometabolic conditions such as high blood pressure, high cholesterol levels, and diabetes were found to have the most impact on poor brain health;
- Mental health and respiratory conditions were not consistently associated with poorer brain health.
Dr Shehab Abid, DPhil candidate at Oxford Population Health, said ‘Multimorbidity is highly heterogeneous. Two individuals might both meet the criteria for multimorbidity, but be living with completely different health conditions. To explore this further, we used a data-driven latent class approach and identified five distinct disease clusters. Interestingly, we found that a cluster primarily driven by cardiometabolic conditions was consistently associated with poorer brain health across all outcomes. These results emphasise that the relationship between multimorbidity and poorer brain health is not simply due to the presence of multiple conditions or a random pattern of diseases but instead suggests that cardiometabolic conditions play a central role in driving the associations between multimorbidity and poorer brain health.’
Dr Thomas Littlejohns, Senior Epidemiologist at Oxford Population Health, added ‘These findings are consistent with our previous research, which has shown that living with multiple health problems, particularly cardiometabolic conditions, is related to an increased risk of dementia. Understanding the interplay between multiple, often diverse, health conditions might be important to maintain good brain health and reduce the likelihood of developing dementia