Research study published in the Journal Psychology and Aging had found that less volume of white matter in the frontal lobe of the brain in some old age people is the cause of decline in brain activity. The researchers have found that the decline in brain activity in the old people is not age related but due to not using the white matter (frontal lobe) of the brain.
Study found that old people mostly use the left side of the brain which contains the Grey matter and not using the front lobe region of the brain which contains the white matter. Grey matter of the brain contains neurons and the white matter helps in connecting the left and right lobes of the brain for good functioning of the brain. Using effectively the white matter (front lobe) of the brain helps in good brain activity and an old brain can think and work as a teenager brain.
The study was conducted in 40 people between the age group of 19 to 87 and the brain functioning was determined by MRI (Magnetic Resonance Imaging) testing. Dr. Stan Colcombe, Scientist, University of Illinois "Old age people use less volume of the frontal region of the brain and concentrated more on the left side of the brain which is the cause of less brain activity".