- Cardiovascular disease (CVD) affects around 550 million people worldwide, and its prevalence has doubled since 1990.
- CVD has been associated with cognitive impairment and dementia in older people.
- The incidence and mortality of CVD among young and middle-aged adults have been steady or increasing in recent years.
- New research has found that people with early CVD may be more likely to have memory and thinking problems and worse brain health in middle age.
Cardiovascular diseases (CVD) are a major cause of global mortality and disability. Although the CVD burden is declining in those aged over 50, current rates of CVD below this age have either remained steady or increased.
In high-income countries, lifestyle factors, such as obesity, lack of physical activity, and poor diet, are all increasing the incidence of CVD.
Studies have shown that cardiovascular risk factors may contribute to late-life cognitive decline and dementia but, until now, there has been little evidence that CVD might speed cognitive decline in middle age.
Now, new research, part of the Coronary Artery Risk Development in Young Adults (CARDIA) study, has found that premature CVD — at or below the age of 60 — may affect brain health and increase cognitive decline in midlife.
The research appears in Neurology, the journal of the American Academy of Neurology.
Long-term study
This prospective cohort study enrolled people aged between 18 and 30 years, and followed them for 30 years. Participants had follow-up examinations every 2–5 years during the study.
The participants were from four cities in the United States, just over half were female and just under half were Black.
Dr. Sandra Narayanan, board-certified vascular neurologist and neurointerventional surgeon at Pacific Stroke & Neurovascular Center at Pacific Neuroscience Institute in Santa Monica, CA, who was not involved in the study, commented for Medical News Today:
“The longitudinal, prospective study design over 30 years limits bias. The number and forms of cognitive assessments applied to this large cohort during this period also enabled a thorough evaluation of brain health in multiple domains such as executive functioning, processing speed, and verbal learning and memory.”
At the 30-year point, 3,146 participants, with a mean age of 55 years, underwent a range of cognitive assessments. In total, 147 (4.7%) had developed one or more premature CVD events, 126 of which were coronary heart disease or stroke. The mean age of the first CVD event was 48.4 years.
Those who had premature CVD were more likely to be male, older, Black, have had access to less education, have lower household income, and have more risk factors for CVD, such as poor diet and low levels of physical activity.
Wide-ranging cognitive assessments
Researchers tested participants in verbal fluency, global cognition, verbal memory, processing speed, and executive function.
They adjusted for demographics, education, literacy, household income, depressive symptoms, physical activity, diet, and APOE — a gene that is linked to an increased risk of dementia — when analyzing their findings.
In addition, they assessed 5-year cognitive decline in 2,722 people who underwent testing at both the 25- and 30-year points.
At the end of the study, 663 participants also underwent MRI brain scans to assess white matter hyperintensities (WMH), which are associated with cognitive impairment. The researchers also used diffusion tensor imaging to assess participants’ brain health.
Only a small proportion of those undergoing MRI scans had early CVD, as lead author Dr. Xiaqing Jiang, a postdoctoral scholar in the Department of Psychiatry and Behavioural Sciences at the University of California, San Francisco, told MNT.
“Among those with MRI, 16 participants had premature CVD. More people will develop premature CVD events as they age as most participants were still under 60,” she said.
Impaired cognition
People who had premature CVD performed worse on all cognitive tests, except verbal fluency. The association was strongest for processing speed and executive function.
However, in women, premature CVD was significantly associated with lower verbal fluency — an association that did not occur in men. Black men with premature CVD had a greater decrease in executive function than what occurred in others with premature CVD.
Those with early CVD were almost three times as likely to show accelerated cognitive decline. Researchers detected it in 13% of those with premature CVD, compared with 5% of those without premature CVD.
Dr. Giovanni Schifitto, professor of neurology at the University of Rochester Medical Center, not involved in this study, explained why early CVD might have these effects.
“Early CVD risk factors also affect cerebral perfusion (brain vessel disease) which can lead to neuronal dysfunction and death,” he told us.
“Cardiovascular disease is closely linked to [the] progression of cerebrovascular disease due to alteration of cerebral blood flow, increased cerebral inflammation and microvascular stress, shared vascular risk factors, and in many cases, shared pathophysiology,” explained Dr. Narayanan.
“Clinically silent white matter lesions, mild cognitive impairment, and overt vascular dementia are linked to increasing burden of these vascular risk factors,” she added.
Brain structure changes
The researchers also found a significant association between early CVD and changes in brain white matter. Changes in white matter often occur in dementia patients.
“In this biracial cohort of middle-aged adults, we found that having premature CVD was associated with worse cognitive performance on most domains, accelerated cognitive decline over 5 years, and worse white matter health, which was not entirely driven by stroke/ TIA [transient ischaemic attack] and even independent of cardiovascular risk factors.”
– Dr. Xiaqing Jiang
Protect the heart to protect the brain
This study highlights the importance of minimizing risk factors for CVD early in adulthood.
The Centers for Disease Control and Prevention (CDC) recommend increasing physical activity, following a healthy diet, not smoking, and maintaining a healthy weight to keep the heart healthy.
And, as Dr. Schifitto pointed out, “[t]here is emergent literature that CVD risk factors should be aggressively treated even at a young age to protect the brain.”
Dr. Jiang agreed, saying that “CVD prevention and intervention, including preventing cardiovascular and other risk factors, may start as early as young adulthood, which may be critical to prevent early divergences of cognitive function and brain health.”
“More research is needed to understand why premature CVD is independently associated with cognition and how these associations evolve over the life course as people get older,” she added.
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