Adult siblings of individuals with Down syndrome versus with autism: findings from a large-scale US survey.
Adult siblings of people with Down syndrome feel closer and healthier than autism siblings, but both groups drift apart once the disabled sibling hits mid-life.
01Research in Context
What this study did
Plant et al. (2007) asked 1,036 adult brothers and sisters to fill out a mail survey. Half had a sibling with Down syndrome. Half had a sibling with autism.
The survey asked how close they felt, how often they visited, and how they rated their own health and mood.
What they found
Down-syndrome siblings reported warmer, less tense relationships. They also said they felt a little healthier and less depressed.
Contact and warmth dropped in both groups once the disabled sibling passed age 45.
How this fits with other research
Cohn et al. (2007) used the same 2007 data set and found the same pattern: autism siblings felt less close and more pessimistic.
Rossetti et al. (2020) later interviewed both siblings together. They showed the Down-syndrome pairs gave and received more everyday help.
Dudley et al. (2019) looked at teens instead of adults. Autism siblings aged 11–18 already reported higher stress, so the gap starts early.
Alon (2025) found one reason: siblings who see life as predictable and meaningful (high “sense of coherence”) stay more positive, especially in autism families.
Why it matters
When you meet a family, ask how the sibling is doing. If the client has autism, the brother or sister may need extra support now, not later. Build small, planned visits or video calls into the behavior plan so the tie stays strong as both siblings age.
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02At a glance
03Original abstract
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.
Journal of intellectual disability research : JIDR, 2007 · doi:10.1111/j.1365-2788.2007.00994.x