The relationship between symptoms of autism spectrum disorder and visual impairment among adults with intellectual disability

Abstract

The higher prevalence of autism reported in blind children has been commonly attributed to the confounding effects of an underlying intellectual disability. The aim of this study was to explore the relationship between symptoms of autism and blindness in adults with intellectual disability. We hypothesized that blindness can increase the probability of the autism phenotype, independent of known risk factors, that is, severity of intellectual disability and gender. A general population case register (population size of 0.7 million) was used to conduct two studies. The first study was on 3,138 adults with intellectual disability, using a validated autism risk indicator to study adults with visual impairment. This identified 386 adults with partial and complete visual impairment, both of which were associated with presence of high number of autistic traits (P < 0.001). The second study was only on those with congenital blindness using a standardized assessment tool, the Pervasive Developmental Disorder-Mental Retardation Scale. Those with hearing impairment or unilateral, partial, and acquired visual impairment were excluded. Control groups were randomly selected from those with normal hearing and vision. Prevalence of the autism phenotype was higher among those with congenital blindness (n = 46/60; 76.7%) than their controls (n = 36/67; 53.7%) and this association was statistically significant (adjusted odds ratio = 3.03; 95% confidence interval: 1.34-6.89; P = 0.008). Our results support the hypothesis that a congenital blindness independently affects psychosocial development and increases the probability of the autism phenotype. Early identification of autism could facilitate appropriate psychosocial interventions and educational opportunities to improve quality of life of people with blindness.Lay Summary: Although autism has been commonly reported in those with blindness, it is generally attributed to an accompanying intellectual disability. Current study, however, revealed that congenital blindness is independently associated with symptoms of autism. In spite of its high prevalence, autism can be overlooked in those with intellectual disability and blindness. Improving diagnosis in this population should, therefore, be advocated through raising awareness of this association to facilitate early access to services.

Prevalence of mental health conditions, sensory impairments and physical disability in people with co-occurring intellectual disabilities and autism compared with other people: a cross-sectional total population study in Scotland

“…12 This was in contrast with the larger study reporting more autistic symptoms in adults with intellectual disabilities and visual impairments than in adults with intellectual disabilities but without visual impairments. 16 Adults with autism have been reported to have more blindness or partial sight loss, and deafness or partial hearing loss than other people (12.1% and 17.5%), 6 as have children with autism (3.5% and 2.9%), 7 and people (children and adults combined) with intellectual disabilities compared with other people (13.1% and 12.4%), 3 using the same data from Scotland's Census 2011 as in this current paper. This current study found the comparable rates for people with co-occurring intellectual disabilities and autism for blindness or partial sight loss, and deafness or partial hearing loss was 21.7% and 19.3% for adults, and 16.6% and 10.3% for children.…”

“…12 An intellectual disabilities register study reported that 95 of the 368 (25.8%) adults with intellectual disabilities who had visual impairment also had markers for autism, compared with 422 of 2674 (16%) of those who had normal vision and that 46 of the 60 (76.7%) of the adults with intellectual disabilities and congenital blindness also had markers for autism compared with only 36 of the 67 (53.7%) with normal vision. 16 We have not identified other papers on sensory impairments or any on physical disabilities in people with co-occurring intellectual disabilities and autism. However, previous large whole population studies that analysed data from the Scotland's Census 2011 have reported that of people with intellectual disabilities, 12.4% reported blindness/sight loss, 13.1% reported deafness/hearing loss and 32.6% reported physical disability.…”

Comorbidity and health services' usage in children with autism spectrum disorder: a nested case–control study

“…In our study, we found a higher prevalence of visual and auditory impairments in children with ASD. Indeed, the associations of both these sensory impairments with ASD were also observed in other studies (Doshi-Velez et al ., 2014; Engelchin-Nissan and Shmueli, 2015; Kiani et al ., 2019). Yet, controversy still exists in the literature regarding the prevalence of hearing impairments in individuals with ASD (Beers et al ., 2014).…”

The inter-relationships between cerebral visual impairment, autism and intellectual disability

“…Learning difficulties due to failure to cater for CVI can thus resemble a primary intellectual deficit (Boot et al, 2012;Flanagan et al, 2003). Several signs can closely resemble a range of neurodevelopmental disorders such as ASD or Attention Deficit Hyperactivity Disorder (ADHD) (Fazzi et al, 2019;Jure et al, 2016;Kiani et al, 2019;Koller, 2012;Mukaddes et al, 2007).…”