Autism not linked with increased age-related cognitive decline

(Press-News.org) There is no difference over time in the spatial working memory of older people who have autistic traits and those who are neurotypical, finds a new study led by UCL researchers.

The new research, published in The Gerontologist, is the first study to explore age-related rate of decline in spatial working memory in older people who may be autistic.

Spatial working memory helps people to remember and use information about where things are and how they are arranged. It is typically used for tasks that involve navigating spaces or organising objects.

As people get older, spatial working memory can sometimes become less effective, which is an example of cognitive decline.

This decline can be a part of normal aging, but it can also be more pronounced in conditions like Alzheimer's disease.

Spatial working memory can also be affected in autistic people - especially when it comes to tasks that involve remembering and organising visual information. Consequently, there has previously been debate over whether autism may lead to increased risk of cognitive decline and, by extension, future dementia.

For the new study, the research team used data from 10,060 people over the age of 50 in the UK who had been assessed as having autistic traits - such as difficulty with social communication and interaction, and restricted or repetitive behaviours or interests - from the PROTECT study.

They found that 1.5% of the cohort had high levels of autistic traits and may be autistic, which is comparable to prevalence estimates of autism in the general population.

The team analysed this data using a method called growth mixture modelling to see how participants’ spatial working memory changed over a seven-year period.

The findings of the study showed that most people, whether they had high levels of autistic traits or not, maintained their cognitive ability over time. This suggested that autistic people were not more likely to experience cognitive decline in this domain.   

Corresponding author, Professor Joshua Stott (UCL Psychology & Language Sciences) said: “Autism is a neurodevelopmental condition associated with differences in social communication and repetitive patterns of sensory motor behaviours.

“It is known that autistic people often also have cognitive differences relative to non-autistic people. In light of this and a current global World Health Organisation-led focus on prevention of cognitive decline and dementia, there has been considerable interest whether having a neurodevelopmental condition like autism can affect your risk of age-related cognitive decline, and potentially dementia.

“Our work provides no support for any difference between autistic people and neurotypical people in terms of increased risk of age related cognitive decline While there are limitations and more studies are needed, looking directly at other aspects of cognitive decline and dementia risk in community rather than healthcare records samples, this research provides useful evidence that can hopefully help to reassure autistic people about this concerning issue.”

Previous research has indicated that there may be higher dementia rates in older adults with autism.

However, these studies, which look at healthcare records, are hindered by the very low diagnostic rate of autism in older people (around one in nine adults over the age of 50 are diagnosed in the UK) meaning that they only look at a very particular and small subsample of autistic people, who probably have more healthcare difficulties and consequently are at greater risk of dementia than autistic people in general.

Meanwhile, other studies that support the theory that autism has no extra effect on cognitive decline have previously only looked at whether autistic people differ in cognition from non-autistic (neurotypical) people at a single time point – rather than tracking changes over time.

Senior author Dr Gavin Stewart, British Academy Postdoctoral Research Fellow at the Institute of Psychiatry, Psychology & Neuroscience at King’s College London, said: “Understanding how ageing intersects with autism is an important yet understudied topic. Getting older often comes with a range of changes, including in health and cognition. As autistic people can be at greater risk of certain health problems and have cognitive differences to non-autistic people, we need to know whether autistic people will have different patterns of ageing than their non-autistic peers.

“This study provides some reassuring evidence that some aspects of cognition change similarly in autistic and non-autistic populations.”

Future studies should test people for a longer time and include a wider age range to understand memory changes better. These findings also need to be replicated in samples who meet diagnostic criteria for autism.

This work was supported by the Dunhill Medical Trust, the National Institute for Health and Care Research (NIHR), Economic and Social Research Council (ERC), Alzheimer’s Research UK, and the British Academy.

Study limitations

The study only included people who could use a computer and the internet, so it might not represent all older adults in the UK.

Meanwhile, the test for autistic traits mainly looked at social and communication issues, not other autism-related behaviours, which might affect the results.

And most participants were white, so the findings might not apply to people from other ethnic backgrounds.

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