Memory brain areas particularly vulnerable to reduced blood flow

Posted on 8th November 2017

A new study from researchers in the US suggests that older people whose hearts pump less blood have reduced blood flow in areas of the brain that control memory. The study was published today in the online issue of Neurology, the medical journal of the American Academy of Neurology.

To support its many functions, the brain receives around 15% of our blood supply. Blood flow to the brain declines as people age and previous research has suggested that a reduction in the amount of blood reaching the brain may increase the risk of Alzheimer’s disease. This research aimed to investigate the impact of blood flow from the heart to the brain in older adults.

The study involved 314 members of the Vanderbilt Memory & Ageing Project, a large study investigating heart and brain health over time. Participants had an average age of 73 and had no history of heart failure, stroke or dementia. Almost 40% of these people had mild cognitive impairment, early memory and thinking problems not severe enough to be classified as dementia. During the study, participants received echocardiograms to record their cardiac index, a measure of how much blood the heart pumps relative to a person’s body size. The researchers also used MRI brain scans to measure blood flow in the participants’ brains.

The findings suggest that a lower cardiac index corresponds to lower blood flow in the temporal lobe of the brain but not other brain areas. The temporal lobe plays a role in memory as well as a number of other aspects of brain function, and is often the first part of the brain affected by damage in Alzheimer’s disease. The researchers calculated that a one unit decrease in cardiac index was linked to a reduction in blood flow to the temporal lobe equivalent to 15 years to 20 years of brain ageing.

Dr David Reynolds, Chief Scientific Officer at Alzheimer’s Research UK, said:

“We know that the brain needs a healthy supply of blood to support its many activities, so it follows that if the heart is not functioning well, there will be knock-on effects for the brain. What is interesting about this study is that regions of the brain responsible for memory and particularly involved in Alzheimer’s disease, may be more vulnerable to reduced blood flow than other parts of the brain.

“Participants in this study only took part in experiments at one point in time, so it just gives a snapshot into someone’s brain health. To better understand the link between heart function, brain health and the risk of dementia, future studies will need to follow larger groups of people over long periods of time.

“Although this study does not provide any new insights about dementia risk, it does add to the growing evidence that what is good for your heart is also good for your brain. It is never too late or too early to start taking steps to support better heart and brain health. Current research suggests that not smoking, keeping mentally and physically active, adopting a healthy diet, only drinking in moderation and controlling blood pressure and cholesterol can all help to limit our risk of dementia.”

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