Six Weeks to 45 Years: A Longitudinal Study of a Population with Down Syndrome

Background A population sample of people with Down Syndrome, repeatedly studied since infancy, has now been followed up at the age of 45 years. The paper is intended to give an overview of their abilities, as represented by the results of psychological tests, over their life span to date. Methods As at all previous occasions from age 30 onwards, intelligence, language, academic abilities and memory were tested, and self-help skills assessed. Results Mean IQs, both non-verbal and verbal, changed little from age 21 to 45. Disregarding the scores of two women severely affected by dementia, the remainder of the cohort lost over the whole period an average of less than one point in non-verbal IQ and gained over five months in verbal age. Scores on memory tests by some of those not yet diagnosed with AD declined, in some cases significantly, suggesting that other members of the cohort too may be showing the early signs of the disease. Conclusions While most of the cohort show few indications of decline in ability, a number now are or may be affected by AD, and this may require closer monitoring in the future.