Child and Adolescent Mental Health Intellectual Disability (CAMHS-ID) teams have fewer than 10% of the number of staff required to provide the service, according to HSE figures provided to Fianna Fáil.
The figures, contained in a parliamentary reply to a question by party mental health spokesman James Browne, show that only 9% of necessary staff are employed.
The figures come from a HSE team tasked with mapping services across all community health organisations including the HSE and voluntary services, as part of its Vision for Change strategy, and give a glimpse to the current state of services.
The figures show that adult mental health intellectual disability services are at 32%, as per Vision for Change.
It says there is an agreement in principle for extra funding for mental health intellectual disability posts over the next two years, which will bring the figure for adults up to 38% as per Vision for Change, and CAMHS-ID to 24%.
It shows a service plan has been developed by each community health organisation, outlining how they plan to develop mental health intellectual disability services.
A resourcing strategy has been developed to plan how to develop services in a sustainable way, with the aim being to establish "baseline teams" for areas with service gaps, before building up staff.
It says an initial €2m of funding has been approved toward services.
Mr Browne said the fact that only 9% of the staff required for children are in place more than 12 years after Vision for Change was published was "truly shocking".
In a statement, he said early intervention for children with mental health issues was critical.
"For children with an intellectual disability such as autism or Down Syndrome, who also have mental health issues, a lack of early intervention is nothing short of cruel," he said.
Mr Browne noted the HSE answered his question by way of percentage as opposed to actual staff numbers, but his understanding was that 150 staff would be needed for children’s teams - a shortfall of around 137 positions, he added.
He said that around 300 posts are required for adults and that around 100 are in place.