Faster cognitive decline seen after incident coronary events
Accelerated cognitive decline is significantly associated with incident coronary heart disease (CHD) after, but not before or immediately following, ischaemic events, suggests a recent study.
“Attention should be drawn to the long-term cognitive deterioration related to CHD,” researchers said. “Careful monitoring of cognitive function is warranted in CHD patients in the years following the event.”
During a median follow-up of 12 years, incident CHD correlated with faster cognitive decline. Prior to CHD diagnosis, the annual cognitive decline rate among patients was comparable to that of those who remained free of CHD throughout follow-up. [J Am Coll Cardiol 2019;73:3041-3050]
Individuals with CHD did not experience short-term cognitive decline after the event. After multivariable adjustment, global cognition, verbal memory and temporal orientation scores declined significantly faster in the years following CHD diagnosis than they did before the event. Results were consistent in sensitivity analyses.
“Based on repeated cognitive measurements over a long follow-up period, this study revealed a reliable and robust trajectory of cognitive decline, and thus examined the influence of the CHD event over the years before and after the event,” researchers said.
Several mechanisms have been proposed to explain how incident CHD may cause cognitive decline in the long-term. One is by causing cerebral hypoxia and silent brain lesions. In a postmortem study, CHD correlated with cerebral microinfarcts, thereby contributing to cognitive impairment. [Nat Rev Cardiol 2015;12:267-277; Curr Alzheimer Res 2012;9:687-696]
Shared vascular risk factors also link CHD to cognitive decline. Previous systematic reviews found that long-term exposure to such factors starting in early life might contribute to cognitive decline over the life-course through various biological pathways, including oxidative stress, immune responses and endothelial dysfunction. [JAMA 2018;320:657-664; Alzheimers Dement 2015;11:710-717; Lancet Neurol 2006;5:87-96; Stroke 2011;42:2672-2713; Nat Rev Cardiol 2015;12:267-277]
Imaging studies have also shown that vascular risk factors might contribute to the development of neurodegenerative lesions in the brain. [Neurobiol Aging 2012;33:1979-1987; Neurology 2014;83:40-47]
“Although we controlled for several vascular risk factors in the statistical analysis, it is still possible that other risk factors may cause ongoing vascular brain injury, such as microinfarcts and cerebral small vessel disease, thus contributing to cognitive decline and even dementia later in life,” researchers said. [Lancet Neurol 2010;9:689-701; Stroke 2012;43:2526-2534; Lancet 2017;390:2673-2734]
The current study included 7,888 participants (mean age, 62.1 years) with no history of stroke or incident stroke during follow-up from the English Longitudinal Study of Ageing. Cognitive assessment was conducted among participants at baseline (wave 1, 2002 to 2003) and at least one other time point (from wave 2, 2004 to 2005) to wave 8 (2016 to 2017). Incident CHD was identified as a diagnosis of myocardial infarction and/or angina during follow-up.
“Future studies are warranted to determine the precise mechanisms linking incident CHD to cognitive decline,” researchers said.