A new twin study has suggested that the same genes may be responsible for the risk of both cardiometabolic diseases, such as stroke and dementia.
Thus meaning that being affected by several cardio metabolic diseases such as stroke and heart disease, is linked to a greater increased risk of Alzheimer’s and dementia.
The authors of the study acknowledge the growing challenge in society that cardio metabolic diseases are causing.
They also note that with an ageing population, along with improved healthcare, individuals are able to live longer with cardio metabolic diseases and are more likely to get two or more of these conditions in their lifetime, which is also known as cardio metabolic multimorbidity.
An estimated 30 per cent of older adults are affected by metabolic multimorbidity, which leads to an increased mortality.
Study first author, Abigail Dove, says: “We know that type 2 diabetes, heart disease and stroke are well-established individual risk factors for dementia. As the population ages, more and more people are affected by several co-morbid cardiometabolic diseases, but few studies have dealt with the effect of this multimorbidity on dementia risk and whether genetic factors affect the relationship.”
The Twin Study
In this study, the researchers examined twins over the age of 60 who were registered in the Swedish Twin Registry between March 1998 and December 2002, more than 17,000 individuals were categorised based on whether they had one or more cardio metabolic diseases or whether they were free of those conditions.
All of the study’s participants were cognitively healthy at the beginning of the study.
The participants’ health status was monitored for up to 18 years, which allows the researchers to establish who eventually developed dementia and who did not.
Dove says: “We discovered that cardiometabolic multimorbidity is linked to a more than doubled risk of vascular dementia and a 50 per cent increased risk of Alzheimer’s disease.”
For each cardiometabolic disease an individual had, the risk of all types of dementia increased by 42 per cent. The corresponding figure for Alzheimer’s disease is 26 per cent and 64 per cent for vascular dementia.
Higher risk for early onset of disease
The study also discovered that the risk of developing dementia was higher if a person was diagnosed with cardio metabolic diseases in middle age compared to if those diseases developed in later life.
The study suggests that one explanation for this may be that if the disease debuts earlier in life, it can be a more aggressive form.
Dove says: “These findings underscore the need for special monitoring of individuals with cardiometabolic diseases to reduce their risk of developing dementia at an older age.”
Influence of genetic factors
The researchers done a closer examination of an estimated 400 specific pairs of twins from the study population that were “mismatched”, which is where the two twins in a pair differed from each other in terms of both the prevalence of cardio metabolic disease and the possible development of dementia.
Amongst these mismatched twins who share 50 per cent of their genes, the twin with cardio metabolic disease was more likely to also be the one who developed dementia.
However, amongst these pairs of identical twins who are genetic copies of each other, the risk of dementia was similar for both twins regardless of cardiometabolic status.
Dove concludes: “The results suggest that the same genetic factors may contribute to both cardiometabolic diseases and dementia.”
