The connection between blood flow from your heart to your brain has been proven to be even more critical for your memory function as you age than scientists once knew.
Keeping a healthy mind as we age is crucial because if you are aging, so is your brain. Even a healthy adult can lose 5% of their brain volume per decade after age 40, with that loss increasing exponentially after age 70. And with this cognitive decline can come difficulty making and retrieving memories.
But another factor is playing a crucial role in memory.
Data from a longitudinal study focused on the “vascular health and brain aging” of participants in the Vanderbilt Memory & Aging Project  shows that the quality of blood flow to the brain in advanced age plays a critical role in the brain’s temporal lobes, also known as the memory “hub.”
So what does this mean for your memory and brain health as you age?
MILD COGNITIVE IMPAIRMENT (MCI) AND ALZHEIMER’S/DEMENTIA OUTLOOKThe purpose of the study led by researchers at Vanderbilt University, published in the journal Neurology, was to investigate the link between cardiac index, or the blood flow pumped from the heart and cerebral blood flow, or blood flow to the brain.
Of the 314 participants in the study, the average age was 73 years old, with 59% being male, and 39% having been diagnosed with mild cognitive impairment (MCI).
Memory or thinking problems can occur in some older adults, a condition that is referred to as MCI. There is no single cause of MCI but the risk for developing the condition increases with age. Conditions such as diabetes, depression, and stroke may increase a person’s risk for MCI.
Symptoms of MCI may include:
- Losing things often
- Forgetting to go to events or appointments
- Having more trouble finding words than one’s peers
- Some movement difficulties and problems with the sense of smell.
Not everyone with MCI will go on to develop dementia. Many times, the symptoms of MCI stay the same or even improve.
But findings from the Vanderbilt Memory & Aging project study, tie lower cardiac index in older adults to reduced cerebral blood flow in the brain’s key memory region. 
CARDIAC BLOOD FLOW PLAYS A KEY ROLE IN MEMORY FUNCTION
Study co-author, Dr. Angela Jefferson, and her team became interested in the link between cardiac index measurements and cerebral blood flow after some of their previous research revealed a correlation with cognitive impairment diseases such as Alzheimer’s. 
“Our prior research findings,” said Dr. Jefferson (to Medical News Today), “have shown reductions in cardiac function are related to abnormal brain changes in older adults, including cognitive impairment, Alzheimer’s disease, and dementia.”
The team used echocardiograms to measure the participant’s cardiac index and MRI to assess cerebral blood flow.
From these tests, the team was able to determine that low cardiac index is tied to reduced cerebral blood flow. This being especially true for the temporal lobes which play a key role in memory creation and storage.
Finding show that in the left temporal lobe, blood flow was reduced by 2.4 milliliters, on average, for 100 grams of tissue per minute, for each unit decrease in cardiac index. In the right temporal lobe, there was an average reduction of 2.5 milliliters of blood for 100 grams of tissue per minute.
For consistent results, the scientists adjusted for confounding variables within their participant pool such as the MCI diagnosis, age, education level, and the presence of the APOE ε4 gene associated with and increased risk of developing Alzheimer’s disease. 
“The primary finding,” Dr. Jefferson said, “was that lower cardiac index related to lower cerebral blood flow in the temporal lobes, the brain’s memory center and the area where Alzheimer’s disease first develops in the brain.”
“The magnitude of these associations corresponded to 15 to 20 years of advanced aging.”
THE IMPORTANCE OF CARDIOVASCULAR HEALTH AS YOU AGE
While the study has some limitations, including the fact that the results do not clearly explain causality, it is possible that reduced cerebral blood flow may be the cause and not the effect.
And the population sample of participants in the study featured mostly white, healthy, and well-educated adults. Results may differ for other sample groups.
But Dr. Jefferson wants to emphasize the importance of looking after cardiovascular health due to its potential wide-ranging effects on overall health, especially later in life. “It is increasingly well-recognized that there is an important connection between heart health and brain health.”
Managing blood pressure, metabolic health, health weight, and regular physical activity are all effective things older adults can do to maintain good heart health, “which may have very important implications for preserving good brain health,” Dr. Jefferson recommended.
“We believe this study offers an initial step in identifying mechanisms linking heart health and brain health.”
“Once confirmed, we hope these mechanisms will offer new prevention or treatment strategies for conditions characterized by cognitive impairment, such as Alzheimer’s disease and dementia.”
Dr. Jefferson says the next step will be to continue to track the participants cardiovascular health and cognitive abilities in hopes to gain a better understanding of the mechanisms that connect heart and brain health and their impact on cognition later in life.
“Following these older adults over time,” Dr. Jefferson said, “offers important future opportunities to investigate mechanisms linking cardiovascular integrity with abnormal brain changes in older adults, including memory loss and cognitive impairment.”