Down syndrome in adults: a 27-year follow-up of adaptive skills.

In 1988, we assessed the adaptive skills of 45 adults with Down syndrome (DS) (21 women and 24 men, age 20-58) with the Portage scale. Since then, we have followed them and also screened for signs of clinical dementia with the Present Psychiatric State - Learning Disabilities assessment. The mean adaptive age (AA) of the study group decreased with increasing age; the age of 35 being the turning point in the clinical course of DS. The mean AA was 4.4 years between ages 20 and 34, 3.4 years between ages 35 and 49, and 2.4 years between ages 50 and 66. Inter-individual variation was, however, large. Between ages 20 and 25, the AA of the study subjects ranged from 2.3 to 6 years; and after the age of 50, from 0.3 to 4.8 years. By the end of the study, all subjects showed signs of clinical dementia. These appeared most frequently as reduced self-care skills, loss of energy, forgetfulness, and impaired understanding. We found no connection between apolipoprotein E genotype and the clinical course of DS. We recommend follow-up of adaptive skills and screening for dementia signs in adults with DS.