The National Autistic Society Scotland says that there are thousands of people with autism who are aged over 50 whose condition is often misunderstood by health professionals.
People with the condition met Mark McDonald MSP at the Scottish Parliament yesterday and urged him to raise their plight with the Scottish Government.
Ministers are due to roll out their Autism Strategy for Scotland, which will provide £13.4 million in funding to support people with the condition.
However, question marks exist over the form effective support will take in the long-term for those with autism.
Robert MacBean, policy and campaigns officer for The National Autistic Society Scotland said: "Too many older adults with autism are missing out on diagnosis entirely and too many are still waiting for their needs to be assessed."
Around 58,000 people are estimated to have autism in Scotland.