Balance marks cognitive changes in old age because it reflects global brain atrophy and cerebro-arterial blood-flow

In healthy old age biomarkers such as Balance robustly correlate with measures of mental abilities such as scores on tests of intelligence, reaction times and memory. A plausible explanation is that balance reflects general physiological fitness and so also neurophysiological integrity, but direct evidence is lacking. Brain scans measured age-associated loss of brain volume and cerebro-arterial blood flow (CBf) in 69 volunteers aged from 62 to 81 years who also took the Tinetti Balance test battery, 3 tests of fluid intelligence, 3 tests of decision speed and a memory test. Balance, but not atrophy or CBf, predicted intelligence test scores. Balance, atrophy, and CBf all independently predicted speed and memory scores but, after variance in atrophy and CBf had been considered, predictions from Balance were no longer significant. It appears that in these tests Balance marks cognitive performance in old age because it reflects gross age-related neurophysiological changes.