Like all teenagers, individuals with Down syndrome undergo hormonal changes during adolescence. Therefore, teenagers with Down syndrome should be educated about their sexual drives. Males with Down syndrome generally have a reduced sperm count and rarely father children. Females with Down syndrome have regular menstrual periods and are capable of becoming pregnant and carrying a baby to term, however, they typically have significantly reduced rates of fertility.

People with Down syndrome are living fuller, richer lives than ever before as family members and contributors to their community. Many people with Down syndrome form meaningful relationships and eventually marry. Many adults with Down syndrome develop the skills they need to hold jobs and to live semi-independently. The life expectancy for people with Down syndrome has also increased substantially. In 1929, the average life span of a person with Down syndrome was nine years. Today, it is common for a person with Down syndrome to live to age fifty and beyond.

Premature aging is a characteristic of adults with Down syndrome. In addition, many people with Down syndrome experience dementia (memory loss and impaired judgment similar to that occurring in Alzheimer disease patients). This condition often occurs when the person is younger than forty years old. Family members and caretakers of an adult with Down syndrome must be prepared to intervene if the individual begins to lose the skills required for independent living.