Myocardial infarction leads to speedier decline in cognition, brain health

Myocardial infarction (MI) is associated with a speedier decline in memory and related issues in the years after an MI event, with Black adults having a slower decline than whites. Heart-healthy measures to help prevent MI may be more important for long-term brain health than previously thought, according to a study in JAMA Neurology. In fact, the paper stated “the decline in global cognition after incident MI was equivalent to six to 13 years of cognitive aging, representing an important public health problem.” It’s important to understand vascular contributions to brain health and cognitive decline so approaches for interventions can be developed to help slow or prevent dementia. The heart and brain health are connected. The researchers explain that it's possible an MI event could exacerbate preexisting cerebrovascular disease, such as white matter disease from hypertension. Or, an MI event could trigger a process of vascular dementia via the effects of systemic inflammation. While MI is already associated with incident dementia and cognitive decline, the degree of changes in cognition, race and sex differences, and long-term post-MI patterns have not been well elucidated. To address these issues, the researchers conducted a pooled analysis of six large, U.S., population-based studies, active in time periods from 1971 to 2019—and which included both MI cases and periodic measures of cognition and blood pressure. The Atherosclerosis Risk in Communities Study, the Coronary Artery Risk Development in Young Adults Study, the Cardiovascular Health Study, the Framingham Offspring Study, the Multi-Ethnic Study of Atherosclerosis and the Northern Manhattan Study were all included. Data for people who had a history of MI, dementia or stroke at baseline or before the first cognitive assessment, or where information was incomplete were excluded from the analyses. The primary outcome was change in global cognition, while secondary outcomes were changes in memory and executive function. Statistical methods were used to harmonize the different measures used in the various studies so comparisons could be made. The study included 30,465 adults with a mean age of 64 years, and 56% female. Of these, 1,033 had one or more MI event (137 had two events), and 29,432 did not have an MI event. Median follow-up was 6.4 years. Of those who had at least one MI event, 131 (13%) were Black, 37 (4%) were Hispanic or other, and 865 (83.7%) were white. Of those with no MI event, 8,649 (23%) were Black, 2,399 (8%) Hispanic or other, and 20,184 (68.6%) were white. Data for three cognitive assessments were analyzed from before and after incident MI. These were for global cognition, executive function and memory. For all three levels of cognition, “We did not find a significant acute decrease in cognition at the time of the MI after accounting for individuals’ pre-MI and post-MI cognitive changes over time,” the study noted. “However, we found that incident MI was associated with accelerated cognitive decline over the years after MI.” Some differences stood out for different cohorts. “Compared with pre-MI cognitive trajectories, there was a significantly faster post-MI, long-term decline in global cognition among white individuals. In contrast, there was no change among Black individuals,” the study said—but not for executive function or memory. In general, women who had MI had a slightly slower acceleration of cognitive decline over time than men post-MI, but they had more of an acceleration of decline in executive function. At the same time, “There was no difference by sex in the association between incident MI and memory.” The study helps show “that a decrease in cognition after incident MI was not sudden but happened more slowly over the years,” the authors stated. Overall, the findings “demonstrated an association independent of clinical stroke and AF and not explained by a second MI event.” An editorial in the same journal by Dr. Eric Smith from the University of Calgary and colleagues stated the study showed, as expected, that people with or without MI had a small age-related annual decline in cognition and that this age-related change is apparent in most neuropsychological tests. “However, after MI, the annual rate of decline accelerated, being steeper than in the same individual before their MI and steeper than in individuals who never had an MI. Interestingly, the long-term slope of the decline changed after MI despite no immediate stepwise drop.” The editorial further noted the increased rate of annual decline could not be explained by stroke or new atrial fibrillation. But even with a study of this scale, there can still be limitations. “What these epidemiological studies do not tell us is the reason for the post-MI acceleration in cognitive decline. Understanding the mechanisms for the post-MI decline may offer keys to identifying patients at risk and managing them to prevent decline,” the editorial said. “It would be helpful to know details of the MI that, understandably, were not collected as part of the epidemiological study. This includes whether the MI was associated with ST segment elevation, the vascular territory involved, the distribution of wall motion abnormalities, the overall ejection fraction, and any complicating arrythmia.”

Myocardial infarction leads to speedier decline in cognition, brain health

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