Adult siblings of individuals with Down syndrome versus with autism: findings from a large-scale US survey

Background As adults with Down syndrome live increasingly longer lives, their adult siblings will most likely assume caregiving responsibilities. Yet little is known about either the sibling relationship or the general functioning of these adult siblings. Using a national, web‐based survey, this study compared adult siblings of individuals with Down syndrome to siblings of individuals with autism in terms of a potential ‘Down syndrome advantage’ and changes across age of the brother/sister with disabilities. Methods Two groups were examined, siblings of persons with Down syndrome (n = 284) and with autism (n = 176). The Adult Sibling Questionnaire measured the number and length of contacts between siblings and their brothers/sisters with disabilities; the warmth, closeness and positiveness of the sibling relationship; and the sibling's overall levels of perceived health, depression and rewards of being a sibling. Results Compared with siblings of brothers/sisters with autism, siblings of brothers/sisters with Down syndrome showed closer, warmer sibling relationships, along with slightly better health, lower levels of depressive symptoms and more contacts. Across age groups of the brother/sister with disabilities, both groups showed lessened contacts, with less close sibling relationships occurring when brothers/sisters with disabilities were aged 30–44 years and 45 years and older (in Down syndrome) and 45 years and older (in autism). Within both groups, closer sibling relationships were associated with more frequent and lengthy contacts, brothers/sisters with disabilities who were better at maintaining friendships and had lower levels of behavioural/emotional problems, and siblings who felt themselves more rewarded by being a sibling to a brother/sister with disabilities. Conclusions In line with earlier work on families of children with disabilities, this study shows an advantage for siblings of adults with Down syndrome, in terms of both sibling relationships and of slightly better health and lessened depressive symptoms. Both joint contacts and close sibling relationships do, however, differ when the brother/sister with disabilities is older. As the first generation of probable caregivers, siblings of persons with Down syndrome who are in their forties, fifties and sixties require increased research attention.