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A recent study investigated whether adults with congenital heart disease have an increased risk of developing dementia.
Congenital heart disease is a heart abnormality or defect present at birth. Occurring in approximately six to ten per 1000 births, congenital heart disease is the most common malformation in newborns. Due to recent medical advances, however, the survival of children with congenital heart disease has greatly increased. Therefore, attention is now being paid to common morbidities (co-occurring disease) acquired by adults with congenital heart disease.
A known adverse outcome associated in children born with congenital heart disease is neurodevelopment deficits during childhood and early adulthood. However, there is limited research into the long-term neurological outcomes. As life expectancy in the general population increases the prevalence of dementia, one of the most important late-life neurological diseases, also increases. It is the fifth most common cause of death in Denmark and sixth in the United States.
What are the Risks Associated with Congenital Heart Disease?
Risk factors associated with dementia are significantly increased in people with congenital heart disease, including genetic disorders such as Down Syndrome. Cardiovascular diseases such as stroke, high blood pressure, heart failure and diabetes, along with some adults having poor exercise tolerance are also risk factors for developing dementia. Therefore, researchers have hypothesised that the risk of developing dementia is increased in adults with congenital heart disease when compared to the general population.
Researchers in Denmark conducted a nationwide population-based cohort study to investigate this hypothesis. The study included 10,632 adults with congenital heart disease and for each of these, ten individuals from the general population were randomly selected, matched on sex and year of birth. The individuals included in the study were followed from 30 years of age or the date they were first registered with congenital heart disease (whichever was the latter). Follow-up on these individuals continued until whichever event came first, either an individual was diagnosed with dementia, death, emigration, or the end of the study period (December 31st, 2012). The results were recently published in Circulation.
Congenital Heart Defects Increase Risk of Dementia
While the incidence rates increased with age in both cohorts, the rate at which the incidence raised for the congenital heart disease cohort was much greater. Compared with the matched general population, the risk of developing all-cause dementia in adults with congenital heart disease was increased by approximately 60% and the risk of developing early onset dementia (where an individual is under the age of 65) was much higher also than late-onset dementia. The relative risk of dementia was elevated for all levels of congenital heart disease complexity, including whether or not an individual had cyanotic lesions, chromosomal abnormalities, acquired morbidities such as diabetes or cardiovascular diseases.
The limitations of the study included surveillance bias, where an overestimation of the risk of dementia in the congenital heart disease cohort may have occurred as this population may have had more frequent contact with medical providers compared to the general population. Furthermore, the researchers note it is important to take into consideration the birth period (1980-1982) of the individuals included in the study, as this represents an era where medical and surgical interventions for congenital heart disease was much more limited compared to today. Therefore, these results cannot necessarily be directly generalised for children diagnosed today with congenital heart disease.
In conclusion, the results show that adults with congenital heart disease are a vulnerable population with an increased risk of developing dementia, particularly early-onset. This highlights the importance of further research needed into understanding the long-term risks of adverse neurological outcomes in adults with congenital heart disease. As most forms of dementia do not have any disease-modifying therapies available, identifying the influence of risk factors on congenital heart disease as targets for future research which could potentially help delay dementia onset is also crucial.
Written by Lacey Hizartzidis, PhD
Reference: Bagge C N, Henderson V W, Laursen H B, Adelborg K, Olsen M and Madsen N M. Risk of Dementia in Adults With Congenital Heart Disease: Population-Based Cohort Study. Circulation. 2018; CIRCULATIONAHA.117.029686. doi.org/10.1161/CIRCULATIONAHA.117.029686.