In a good news for the elderly people, researchers have found that aerobic exercise boosts blood flow to two key regions of the brain associated with memory.
The study, published in the Journal of Alzheimer's Disease, showed that this blood flow can help even older people with memory issues improve cognition.
These findings have major implications for future Alzheimer's disease research. "Perhaps we can one day develop a drug or procedure that safely targets blood flow into these brain regions," said study researcher Binu Thomas from the University of Texas Southwestern in the US.
The study documented changes in long-term memory and cerebral blood flow in 30 participants, each of them 60 or older with memory problems.
Half of them underwent 12 months of aerobic exercise training; the rest did only stretching. The exercise group showed 47 per cent improvement in some memory scores after one year compared to minimal changes in the stretch group.
Brain imaging of the exercise group, taken while they were at rest at the beginning and end of the study, showed increased blood flow into the anterior cingulate cortex and the hippocampus -- neural regions that play important roles in memory function.
Other studies have documented benefits for cognitively normal adults on an exercise programme, including previous research from Thomas that showed ageing athletes have better blood flow into the cortex than sedentary older adults.
The new research is significant because it plots improvement over a longer period in adults at high risk to develop Alzheimer's disease.
"We've shown that even when your memory starts to fade, you can still do something about it by adding aerobic exercise to your lifestyle," Thomas said.
Recent research has helped scientists gain a greater understanding of the molecular genesis of the Alzheimer's disease, including a 2018 discovery from UT Southwestern's Peter O'Donnell Jr Brain Institute that is guiding efforts to detect the condition before symptoms arise.