Study Reveals 90% of Autistic Adults Over 40 Remain Undiagnosed

Research from King’s College London has uncovered that approximately 90% of autistic adults aged 40 and above remain undiagnosed, highlighting a significant oversight in the recognition of autism in older generations. This startling finding reveals the complexities surrounding autism diagnoses and underscores the urgent need for improved support and resources for this demographic.

Historically, autism diagnoses have surged, particularly among younger individuals. From 1998 to 2018, the United Kingdom saw a remarkable 787% increase in autism spectrum disorder (ASD) diagnoses. While this spike is often attributed to greater awareness and more accurate diagnostic criteria, the study emphasizes that many older adults have been left out of this narrative. According to the research, around 89% of autistic adults aged 40 to 59 and an alarming 97% of those over 60 do not possess a formal diagnosis.

Dr. Gavin Stewart, lead author of the study, stated, “These very high underdiagnosis estimates suggest that many autistic adults will have never been recognized as being autistic, and will have not been offered the right support.” This lack of recognition can lead to a range of health challenges, including a fourfold increased risk of early dementia and a sixfold higher risk of suicidal thoughts. The life expectancy of autistic individuals is notably lower, with UK data indicating an average of 75 years compared to 81 years for their non-autistic counterparts.

The implications of these findings extend beyond mental health. Older autistic adults face heightened risks for serious medical conditions, including cardiovascular disease, gastrointestinal disorders, and age-related diseases such as Parkinson’s and arthritis. The study highlights that many autistic individuals over 40 report feeling socially isolated—20% compared to just 4% of their non-autistic peers.

Despite the increase in autism diagnoses among younger populations, older adults often remain invisible within healthcare statistics. A contributing factor is the historical definition of autism, which primarily focused on children and often overlooked adults. For much of the 20th century, autism was narrowly defined, limiting the understanding of the spectrum. As diagnostic criteria have evolved since the 1980s, the focus has shifted to a more holistic view, yet significant gaps remain, particularly regarding older individuals.

In the United States, similar trends have emerged. Research indicates that the prevalence of ASD diagnoses among young adults and certain demographic groups has grown substantially from 2011 to 2022. Nevertheless, the older population has not received adequate attention. A study found that 35.1% of autistic adults aged 64 and older were diagnosed with dementia, compared to 10% of the general population over 65.

As researchers continue to explore the connections between autism and cognitive decline, they emphasize the importance of addressing the unique challenges faced by older autistic adults. The research indicates that these individuals often encounter barriers when seeking healthcare and support, with diagnostic processes still predominantly centered on children.

This study serves as a clarion call for a more inclusive approach to autism research and policy. “Understanding the needs of autistic people as they age is a pressing global public health concern,” remarked Francesca Happé, Professor of Cognitive Neuroscience at KCL. She stressed the importance of developing tailored healthcare and social support systems to improve the lives of aging autistic individuals.

The findings of this significant research are published in the Annual Review of Developmental Psychology, aiming to shed light on the often-overlooked experiences of autistic individuals in midlife and beyond, and to advocate for necessary societal changes. The need for a comprehensive understanding of autism across the lifespan is critical to ensuring that all individuals can achieve optimal health and quality of life as they age.