https://www.medpagetoday.com/cardiology/dementia/69142?
Effect on par with 15 to 20 years of aging, researchers say
Reduced cardiac output was associated with accelerated brain aging in terms of blood flow to memory processing areas, an observational study showed.Lower cardiac index on echocardiography -- adjusted for mild cognitive impairment (MCI), age, education, carriage of the Alzheimer's APOE ε4 gene, and other factors -- correlated to significantly lower left and right temporal lobe blood flow measured on MRI, Angela Jefferson, PhD, of Vanderbilt University Medical Center in Nashville, and colleagues reported online in Neurology.
In the left temporal lobe, there was 2.4 mL less flow per 100 g of tissue/minute for every one unit decrease in cardiac index. In the right temporal lobe, each unit lower cardiac index was associated with 2.5 mL less of blood per 100 g of tissue/minute. These apparent effects were equivalent to the decrease expected over 15 to 20 years of aging.
Other areas of the brain and hypercapnia-induced cerebrovascular reactivity didn't show significant associations.
The Vanderbilt Memory & Aging Project study included 314 people (average age 73) without heart failure, stroke, or dementia at baseline, although 39% had MCI.
A secondary analysis for interaction between cardiac index and cognitive diagnosis, showed the associations held only among cognitively normal participants, not those with MCI. But the findings were independent of prevalent cardiovascular disease.
"Our results suggest mechanisms that regulate blood flow may become more vulnerable as a person ages, even before cognitive impairment sets in," Jefferson said in a press release. "This important observation warrants further study. It is also possible the temporal lobes, where Alzheimer's disease first begins, may be especially vulnerable due to a less extensive network of sources of blood flow. If we can better understand how this process works, we could potentially develop prevention methods or treatments."
The researchers cautioned that with cross-sectional methodology, the results could not determine causality. Also, the largely white, well-educated and healthy population studied might limit generalizability.
"Longitudinal studies are needed to understand the temporal nature of associations reported here," Jefferson's group wrote, adding, "Further investigation into mechanisms linking cardiac index and regional cerebral blood flow is warranted to identify primary prevention targets or therapeutic interventions."
The study was
supported by the National Institute on Aging, National Institute of
Neurological Disorders and Stroke, Alzheimer's Association, American
Heart Association, Vanderbilt Clinical Translational Science Award, and
the Vanderbilt Memory & Alzheimer's Center.
Jefferson and co-authors disclosed no relevant relationships with industry.
Jefferson and co-authors disclosed no relevant relationships with industry.
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