Cognitive and Behavioural Associations of Visual and Hearing Impairments Across the Lifespan in People With Down Syndrome, a Scoping Review.

Background: Hearing and visual impairments are common in individuals with Down syndrome (DS), yet it remains unclear whether sensory impairments are associated with cognitive and behavioural functioning such as language, memory and socialisation. This literature review examines those associations.

Methods: A scoping review of four databases was conducted to examine associations between sensory impairments and cognitive or behavioural outcomes in individuals with DS. Study evidence was assessed based on design, sample size, assessment modalities and statistical significance.

Results: Of 1471 studies screened, 38 met inclusion criteria. Hearing impairments were associated with delays in language and motor development during infancy, lower overall cognitive ability and social communication difficulties in childhood and reduced adaptive functioning and intellectual decline in adulthood. Visual impairments were linked to learning difficulties in childhood and to declines in adaptive behaviour, visual-motor integration and cognitive performance in adulthood. Subdomains of cognitive functioning such as memory, reasoning or processing speed were not reported for adults.

Conclusion: Uncorrected hearing and visual impairments in individuals with DS are associated with a range of cognitive and behavioural outcomes across the lifespan. The strongest associations were observed between hearing impairments and language delays in infancy and childhood, and between visual impairments and adaptive behaviour challenges in childhood and adulthood. Sensory impairments were associated with challenges in similar domains-particularly language, adaptive functioning and learning-across the lifespan. This suggests a potential continuity of these associations over time and that long-standing uncorrected impairments may be associated with reduced cognitive reserve and increased vulnerability to decline-highlighting the need for early identification and intervention.