Additional difficulties - anxiety, autism, ADHD, OCD
Some children with Down syndrome (15%-20%) will have characteristics beyond the typical range of temperamental and personality characteristics seen in most children, such as significant anxiety, hyperactivity or obsessional behaviour. High levels of anxiety will influence children’s social behaviour and anxious children may wish to cling to routines and rituals to give themselves a sense of predictability in their lives, thereby reducing their anxiety levels. Anxious children will not be easy to manage and may have difficulty in relating to other adults and children. Hyperactive and impulsive behaviour can be linked to slow development, as can obsessional behaviours, making it difficult to determine whether these behaviours are actually clinically significant and deserve treatment, or are just part of developmental delay and will improve as development progresses.
There is no evidence to suggest that children with Down syndrome are protected from other disorders of childhood and therefore it can be expected that some children will have autistic spectrum disorders (ASD), obsessional compulsive disorders (OCD), or attention deficit hyperactivity disorder (ADHD). Any of these disorders will influence their social development and make them more difficult to manage, at home and at school.
Unfortunately, it is not always easy to separate out the effects of very slow language and cognitive development on social development from the effects of autistic, OCD or ADHD difficulties and this has recently been recognised by clinicians.[@charman_practitioner_2002] When making slow progress in play and in communication, they often develop behaviours such as lining up toys, twiddling with and fixating on objects, aimless over-activity and impulsivity, or withdrawal into their own world; symptoms also seen in ASD, OCD or ADHD. However, these behaviours on their own are not diagnostic of autism or ADHD but simply reflect the child’s current level of cognitive and communicative ability. These behaviours are also seen in children with brain damage, and in the 11% most delayed group of children with Down syndrome, many of whom are known to have additional brain damage due to illness, trauma or unknown causes.
Studies suggest that up to 30% or more of children with Down syndrome may reach the criteria for ADHD. However, many of the symptoms including hyperactivity, inattention and behaviour issues are common among children with Down syndrome. They may reflect intellectual delays and language delays and also sleep difficulties. However, they may be more severe in children with Down syndrome ADHD and more noticeable at school age when dealing with the challenges of the classroom. [ Esbensen Epstein et al 2022]
One recent study indicates that there is no difference in cognitive or developmental level between those with and without ADHD but that sleep disorders, disruptive behaviours, allergies and seizures are more common in children with DS+ADHD. [Esbensen, Vincent 2022]. The links with sleep disorders suggest that one focus for treatment should be to improve sleep as a child who is tired will be more likely to display ADHD type daytime behaviours [ McConnell et al 2020, Horne et al 2019Stores Stores et al 1998, 2014] Some children with an ADHD diagnosis respond to medication though prescribing patterns may vary between countries.
In a study [@evans_compulsive-like_2000] of obsessional compulsive behaviours in which the behaviours of children with Down syndrome were compared with the behaviours of typically developing children matched for mental age, the incidence and types of behaviours seen were the same in the two groups. This suggests that there was no abnormal increase in the children with Down syndrome in relation to their developmental levels. Ritualistic and obsessional type behaviours are seen in all children and reduce with age. However, the children with Down syndrome engaged in the behaviours more often than the comparison children, but both the number and frequency of the behaviours did fall in the older children.
Down syndrome and autism
The concern that a child with Down syndrome may also have autistic spectrum difficulties has become increasingly common but studies suggest that there is a real risk of overdiagnosis. The diagnosis of autism requires a child to have impairments in 1. social communication and 2. restricted and repetitive behaviours. REF ICD? DSM? Those with more severe impairments may be diagnosed as autistic, and those with less severe impairments as having autistic spectrum disorder (ASD).
Diagnosis is challenging: A review of research studies indicates that some 16% of children with Down syndrome may also have autistic spectrum disorder, with estimates from different studies varying between 7% and over 30%. [Richards, C., Jones, C., Groves, L., Moss, J. & Oliver, C. (2015)]. These differing estimates may reflect the fact that a number of studies indicate that the diagnosis is difficult to make when a child has Down syndrome. Many of the symptoms typically associated with autistic spectrum disorder, such as repetitive behaviours, are common among all children and young people with Down syndrome and as common in those with or without an ASD diagnosis. [Channell, M., Phillips, B.A., Loveall, S.J., Conners, F.A., Bussanich, P.m. & Klinger, L.G. (2015) Godfrey M, Hepburn S, Fidler DJ, Tapera T, Zhang F, Rosenberg CR, & Lee NR. (2019) Channell 2020 Hamner et al 2020]. In addition, one study shows that sensory processing difficulties and maladaptive behaviours are as common among children aged 2-10 years with a diagnosis of Down syndrome as those who had the dual diagnosis of Down syndrome and ASD. [Will EA, Daunhauer L, Fidler DJ, Lee NR, Rosenberg CR, & Hepburn SL. (2019)] These and other studies highlight the real risk of false positive diagnoses based on commonly used autism screeners across the age range from 2 years of age (Buckley, Bennett 2021, DiGuiseppi 2010). In particular, children with Down syndrome with vision or hearing impairments, born prematurely or with a number of additional health conditions are more likely to receive a false positive screen. DiGuiseppi 2010, Fidler Prince 2022.
Autistic profiles may have different causes: Autism is known to have a genetic component and run in families and this has also been shown for children with Down syndrome[Ghaziuddin 1997, Rasmussen et al 2001] . The earliest studies highlighting the genetic risk also reported that autism could be the result of neonatal illness leading to brain damage [e.g. Folstein, Rutter 1977]. A pattern of similar social communicative difficulties and behaviour symptoms can also arise when a child does not experience the same range of early experiences and social learning opportunities as a result of their disabilities. For example, children with significant vision impairments, including CVI (central visual impairment) are known to be at risk for ASD-like profiles as their experience of the social world is limited by reduced opportunities to move, explore and to see social cues. (Chokron 2020).
More cognitively delayed children: A number of studies indicate that many, but not all, children with a dual diagnosis of DS+ASD tend to be more cognitively delayed than most children with Down syndrome. [ Channell et al 2019, Hamner 2020, Fidler Prince 2022] It is not clear whether having ASD is leading to slower cognitive development or that children who start out more cognitively impaired are not able to develop the same social communication skills. Over time, more delayed children, with or without an ASD diagnosis may make slower progress in daily living skills and independence though they will usually steadily progress through to adult years. Life for these children and young people may be more difficult than for most with Down syndrome. They and their families will benefit from extra support from services. Families report benefitting from an autism diagnosis and access to ASD community.
Not typical autism: Whatever the underlying causes, it is also important to note that several studies have reported that children with a correct diagnosis of Down syndrome and ASD show less social communication impairment than other children without Down syndrome and only an ASD diagnosis. They are usually still more socially responsive and want to relate to others. [ Hamner et al 2020] Infants and toddlers with Down syndrome typically show relative strengths in early non- verbal communication skills and are keen to interact with those around them and experts suggest that it is important to recognise this in early intervention. Building on this strength may have a preventative effect and reduce later communication difficulties for those vulnerable to an ASD profile [Hamner et al 2020. Early intervention has been shown to reduce autistic symptoms in children at risk for ASD. Refs [Green et al 2017, 2018]
In summary, for all children with Down syndrome, a preventative approach is important. In addition to supporting all early communication skills, children need support to explore and to develop their play, which may be affected by both motor and cognitive delays. Children may get ‘stuck’ in repetitive play actions without a ‘play partner’ to scaffold their progress. While a diagnosis of ASD may be helpful in obtaining more specialist services, it is equally important to note the wide range of individual differences in the needs of more delayed children and to address the specific communication or behaviour needs of each child, with or without an autism or ASD diagnosis.
