Mounting suspicions of links between coronary artery disease (CAD) and Alzheimer's have been confirmed by a new study that uncovered a significant relationship between the neurodegenerative condition, fats in the blood, and seven characteristics of heart disease.
Further investigation identified genetic links between the traits, highlighting potential targets for further investigation into the origins of both pathologies.
The research team, from Edith Cowan University (ECU) in Australia, dug into large genetic datasets to look for shared genes or gene variations that might increase the risk of Alzheimer's, CAD, and concentrations of triglycerides and lipoproteins – fats that have been implicated in the development of both Alzheimer's and heart disease.
Observational evidence of links between Alzheimer's disease and CAD has suggested the two conditions might share a deeper cause. By including lipids in this latest investigation, the team hoped to get a more detailed picture of how heart health and brain health are related.
"There is considerable evidence from observational and other studies to support a connection between these conditions," says lead author Artika Kirby, a bioinformatician from ECU.
"However, the intricate biological mechanisms of Alzheimer's disease are poorly understood, and its relationship with lipids and CAD traits remains unresolved."
The results from the statistical analysis suggest certain shared genes play a role in Alzheimer's, heart disease traits such as angina and heart attacks, and increasing serum concentrations of lipids, including cholesterol and triglycerides.
However, the data doesn't support a causal link – that the genetic factors behind Alzheimer's disease are also causing heart disease or vice versa. What is shown is that these shared genes could be raising the risk of both of these disease types.
It means that we now have several new biological pathways that can be investigated when it comes to understanding the root causes of both Alzheimer's disease and heart disease – adding to what we know about issues such as inflammation in the body, which is associated with both Alzheimer's and CAD.
"Our study employed a genetic approach to investigate the intricate relationships of these comorbid conditions, providing new insights into their shared biological underpinnings of these conditions," says Kirby.
It's expected that around 139 million people will have Alzheimer's worldwide by 2050. By identifying critical genetic factors, including the increased risk that comes with having two copies of the APOE4 gene, researchers hope to improve on current diagnostic methods. Identifying additional triggers for Alzheimer's – and heart disease – may indicate ways of preventing onset for both condictions.
"I am optimistic that our findings open new avenues of research that have the potential to enhance the lives of millions, worldwide," says Kirby.
The research has been published in the International Journal of Molecular Sciences.