Recently it has been reported that late-onset tremor, gait unsteadiness and dementia can be associated with brain atrophy in males of normal intelligence and the pre-mutation carrier state of the fragile X syndrome. We have shown, by means of a telephone survey, that this association is probably causal rather than coincidental. These findings have uncovered another testable cause of late-onset neurological symptoms in males, which also has serious genetic implications for their daughters who are at risk of having sons with full mutations causing mental handicap - the fragile X syndrome.