Understanding the Experiences of Late Diagnosed Autism and Post-Diagnostic Assessment for Older Autistic Adults

Section one: The Lived Experiences of Autistic People Undiagnosed Until Later in Life: A Systematic Review and Meta-Synthesis
Objectives: This review aims to systematically review, critically appraise and thematically synthesise the data from existing qualitative literature which explores the lived experiences of those who received a late diagnosis of autism. Defined in this review as those diagnosed at twenty-five years old or above. This is with the goal of improving the understanding of the lived experiences of those diagnosed late and to consider what can be done to improve early identification of autism.
Design and Method: Four electronic data bases were searched and 16 studies conducted between 2016-2026 were identified, with 151 participants across the studies. Each study was critically appraised using the relevant Critical Appraisal Skills Programme checklist. Data was extracted and analysed using thematic synthesis.
Results: Three themes were developed: being different, autism difficulties being missed and impact of the late diagnosis. Within these were ten subthemes.
Conclusions: Overall, the findings highlighted the difficult journeys that participants have been on to finally receive an autism diagnosis. The diagnosis was a profound moment of validation which also brought up emotions such as anger and grief at missed support.

Section two: Exploring the Validity, Acceptability and Usability of the International Classification of Functioning, Disability and Health (ICF) Core Sets Assessment Tool for Older Autistic People: A Mixed Method Study
Objectives: Autism is a lifelong neurodevelopmental condition which has a significant impact on day-to-day experiences. It is becoming widely accepted that daily functioning is not appropriately assessed in the current autism diagnostic pathways. In response to this, the ICF Core Sets for Autism assessment tool has been developed to better explore functioning. This research aimed to explore the acceptability, usability and validity of this assessment tool with older autistic people.
Design and Method: This research employed a mixed method design. Fourteen autistic adults over the age of 50 took part. Through engaging in a cognitive interview while completing the assessment tool, validity was explored. Reflexive thematic analysis (RTA) was used to analyse cognitive interview data. Next, measures of acceptability and usability were completed. Descriptive statistics were used to explore the two measures.
Results: The assessment tool was found to be acceptable and usable for older autistic people. Five themes were developed: issues with ambiguity, an assumption of ‘normal/appropriate’, cultural differences, how do I boil that down into a number? and the real me vs. my masked self.
Conclusions: It was concluded that the assessment tool was acceptable and usable for older autistic people. With regards to validity, issues were highlighted in that there were issues with ambiguity, some described that the tool was unable to capture the nuances around the variability of functioning, and some felt that it was unable to account for cultural differences.