There is a finely graded inverse association between age and cognitive performance, 3 4 5 but the age at which cognitive decline becomes evident at the population level remains the subject of debate.5 6 7 A recent review of the literature concluded that there was little evidence of cognitive decline before the age of 60.8 This point of view, however, is not universally accepted.5 6 Clinicopathological studies show good correlation between neuropathology and the severity of cognitive decline, 9 10 11 and
neurofibrillary tangles and amyloid plaques, the hallmarks of
pathology, are known to be present in the brains of young adults.12 13 Emerging consensus on the long gestation period of dementia14 15 also suggests that adults aged under 60 are likely to experience age related cognitive decline.