Couch potatoes may have smaller brains later in life: study

Poor physical fitness in middle age may be linked to a smaller brain size 20 years later, researchers, including those of Indian-origin, have warned.
For the study, researchers from Boston University School of Medicine in US made 1,583 people with an average age of 40 years and without dementia or heart disease take a treadmill test.
They took another one two decades later, along with Magnetic resonance imaging (MRI) brain scans. Researchers also analysed the results when they excluded participants who developed heart disease or started taking beta blockers to control blood pressure or heart problems. This group had 1,094 people.

The participants had an average estimated exercise capacity of 39 mL/kg/min, which is also known as peak VO2, or the maximum amount of oxygen the body is capable of using in one minute.
Exercise capacity was estimated using the length of time participants were able to exercise on the treadmill before their heart rate reached a certain level.
For every eight units lower a person performed on the treadmill test, their brain volume two decades later was smaller, equivalent to two years of accelerated brain ageing, according to researchers, including Sudha Seshadri and Ramachandran S Vasan from Boston University.

When the people with heart disease or those taking beta blockers were excluded, every eight units of lower physical performance was associated with reductions of brain volume equal to one year of accelerated brain ageing.

The study found that people whose blood pressure and heart rate went up at a higher rate during exercise also were more likely to have smaller brain volumes two decades later.
People with poor physical fitness often have higher blood pressure and heart rate responses to low levels of exercise compared to people with better fitness, researchers said.
"We found a direct correlation in our study between poor fitness and brain volume decades later, which indicates accelerated brain ageing," said Nicole Spartano from Boston University.
"While not yet studied on a large scale, these results suggest that fitness in middle age may be particularly important for the many millions of people around the world who already have evidence of heart disease," Spartano said.

The findings were published in the journal Neurology.