1. Diagnosis of Older Generations: Autism spectrum disorder (ASD) was only formally recognized in the Diagnostic and Statistical Manual of Mental Disorders (DSM) in 1980, with significant changes and expansions in diagnostic criteria over the years. Prior to that, many individuals may have been misdiagnosed with other conditions, such as intellectual disability, schizophrenia, or simply labeled as “eccentric.” As awareness and understanding of autism have increased, many older adults may be undiagnosed or misdiagnosed, which explains why we don’t see as many diagnosed elderly individuals. Furthermore, diagnostic services for adults are still lacking, and many older adults may not seek a diagnosis later in life.

2. Gender Disparity: The difference in diagnosis rates between males and females is a recognized phenomenon. However, research suggests that autism may present differently in females, often leading to underdiagnosis or misdiagnosis. Girls may develop better coping mechanisms or mask their symptoms, which can result in them not being diagnosed until later in life, if at all. The historical data on mental disorders does not necessarily reflect the nuanced understanding of autism and its presentation across genders that we have today.

3. Debilitating Nature of Autism: Autism exists on a spectrum, meaning there are varying degrees of severity. Some individuals may have mild symptoms that were previously overlooked or attributed to other behavioral or developmental issues. As awareness has grown, the criteria for diagnosing autism have broadened to include a wider range of symptoms and severities, which accounts for the increase in diagnoses. The perception that autism is always “extremely debilitating” is a misunderstanding of the spectrum nature of the disorder.

4.Historical Reclassification: Several disorders have been reclassified as our understanding of autism has evolved. For example, conditions like Asperger’s syndrome and pervasive developmental disorder-not otherwise specified (PDD-NOS) were merged into the autism spectrum disorder category in the DSM-5. This reclassification has contributed to the increase in diagnosed cases.

Your "proof" lacks support from an extensive body of scientific research. The increase in autism diagnoses is better explained by changes in diagnostic criteria, increased awareness, and better diagnostic tools rather than any new or emerging cause.