Thousands of adults with autism find themselves isolated and ignored, one of the largest studies into people with the condition has suggested.
Autism campaigners have called on the Scottish Government to act
The National Autistic Society Scotland said more than half of an estimated 50,000 autistic adults and their families do not get the support needed.
It claimed the government does not know exactly how many people have autism, making it impossible to plan services.
The charity spoke to 175 adults with the condition and their families.
The I Exist report said thousands of adults with autism faced a "miserable daily reality" which left them feeling isolated and ignored, unable to access the required support, and often completely dependent on their "overburdened" families.
'Bullied or harassed'
One adult with autism told researchers: "My family often have to fight for me to get the support and life that I need. This is a constant struggle."
The report found that 54% of those questioned said they did not receive enough support to meet their needs, with 52% of adults with autism not having had an assessment of their needs since the age of 18.
The report also found that more than half of autistic adults had suffered from depression and had been bullied or harassed since the age of 18. Only one in eight adults with autism was in employment.
Overall, only 56% of adults with autism in Scotland were currently receiving any services, despite there being a clear and ongoing need for more support, the report stated.
Carol Evans, national director of NAS Scotland, called on the Scottish Government, local authorities and local health agencies to accurately record the number of adults in Scotland with autism.
She also said all health professionals should receive training in how to deal with adults with autism.
Ms Evans added: "For too long adults with autism have found themselves isolated and ignored. They struggle to access support and are often hugely dependent on their families.
"It does not have to be like this. 'I Exist' is the message from adults with autism in Scotland who want their needs understood and the barriers to support removed.
"The right help at the right time can have a profound effect - we are calling on the Scottish Government to think, act, and transform lives."
Minister for Public Health Shona Robison said the Scottish Government had funded a number of local and national projects aimed at improving services and support for people with autism spectrum disorders.
She said these included two one-stop shops where adults are able to access information, advice and take part in discussion groups, and that most of those accessing the services received no support in the past.
Ms Robison added: "We are currently developing guidance for commissioners of health and social care services for people with autism spectrum disorder, which will address the need for appropriate and responsive services for people with autism."
Autism is a lifelong developmental disability which occurs in varying degrees of severity. An estimated 50,000 people have the condition in Scotland.
The condition is characterised by difficulties in forming social relationships, problems with verbal and non-verbal communication and the development of narrow obsessional interests.