Heart efficiency relates to brain aging

A new study in the August 2 2010 Journal of the American Heart Association shows what runners have known all along…our brains are bigger! OK, in all seriousness, this is an important study with long term implications. We know that as we age, the size of our brains decreases – just as muscles atrophy, so does the brain. More severe brain atrophy occurs in those with dementia, such as Alzheimer’s disease. By using MRI’s, this study found that decreased cardiac index (the amount of blood that pumps from the heart in relation to a person’s body size) was associated with reduced brain volume. In other words, reduced brain size was associated with the heart pumping less blood.

This was a large study – 1,504 participants in a decades-long study who did not have a history of cardiac disease, stroke, transient ischemic attack or dementia. The researchers noted, “We observed cardiac index is related to structural changes in the brain but not cognitive changes,” Also, “The structural changes may be early evidence that something is wrong.”

The exact cause between heart function and brain volume is still not well understood, the researchers said. “There are several theories for why reduced cardiac index might affect brain health. For instance, a lower volume of blood pumping from the heart might reduce blood flow to the brain, providing less oxygen and fewer nutrients needed for brain cells. It is too early to dole out health advice based on this one finding but it does suggest that heart and brain health go hand in hand.”

The crux of the study is this – while this is an observational study, (i.e. no cause and effect established yet) we know that exercise increases the cardiac index. If cardiac index is associated with reduced brain aging, it makes sense that exercise reduces brain aging. In fact we already know that.

Other related studies:

· This study looked at 1740 people aged 65 or over, all of whom began the study with good cognitive function. After six years, 158 people in the group had developed dementia (107 of the 158 had Alzheimer’s). But those who had exercised at least three times a week were on average 38% less likely to have developed dementia than those exercising less than three times a week.

· This 21 year study of more than 1,400 adults, those who exercised during middle age were 52% less likely to develop dementia and 62% less likely of developing Alzheimer’s than non-exercisers.