Age-specific characteristics and annual changes of social maturity in adults with Down syndrome (DS) were retrospectively investigated. Forty-six individuals aged 15-58 years were enrolled. Social age (SA) in all domains and subdomains was assessed using the revised S-M social maturity test. Thirty-four cases were evaluated for SA changes over time at 1 year. The SA of adult DS tended to be lower in those under 20 and over 42 years of age. The SA of adults with DS was lowest in the Socialization domain, and this trend was generally common across all age groups. The annual decline of SA was more prominent in the DS-AD group than in the non-DS-AD group. Annual decline of SA in the communication domain had the same discriminative power as that in the whole domains in the discrimination of DS-AD from non-DS-AD. These results are expected to contribute to the development of clinical diagnostic methods for DS-AD in the future.
Keywords: Alzheimer’s disease; Down syndrome; acute regression; social maturity.