Background: This descriptive single-case study reports upon a four-decade history of health care and support provided to one male with life-long intellectual disability and significant comorbidities. Methods: All available paper and electronic documentation from the past 40 years was reviewed, with relevant health and medication information collated and summarised. Results: The collated information notes radical movement in mental health diagnoses and significant emerging physical health issues. There are disparate and sometimes contradictory mental and physical health diagnoses from age 2 years and significant changes in treatment. Conclusions: This case outlines a number of important issues for medical and health care practitioners to consider when supporting individuals with intellectual disability. Clear differentiation between an existing intellectual disability, autism, and emerging mental health concerns has remained problematic over many decades. The lack of effective pain management, when contrasted against comprehensive medication regimes for health issues, is particularly concerning.