With the background of 11% of total United States government spending for disability support in 2006, the authors from Boston Children’s Hospital and Harvard Medical School highlight the financial and social imperatives to improve services for people with learning disabilities.

They remind us that most of the current focus on research has been on environmental and supportive management and that there are now increasing prospects for therapeutic interventions on the underlying cause.

Methods

This is a review of current available therapies for some specific causes including preventative therapies and enzyme replacement therapies, which have mixed success in maintaining cognitive function.

However, there are number of innovative treatments being trialled for several disorders including:

• Fragile X
• Tuberous sclerosis
• Rett syndrome
• Down syndrome

These treatments and their modes of action are discussed as well as unmet needs for areas that are likely to continue to be challenging in the future.

Most of the genetic causes of learning disabilities appear to affect the functioning of the neurones’ ability to signal to other neurones.

Results

This review is a comprehensive and structured attempt to appraise a wide range of interventions that may benefit people with a learning disability in the future.  There are insights into the modes of actions of these treatments but because of the heterogeneity of the causes of learning disability, therapeutic advances are unlikely to come from a single approach.

• The paper discusses new uses for currently licensed drugs such as lithium, which has been shown to improve cognition in the Down syndrome mouse model
• Micro RNA may be able to regulate important genes such as MeCP2 in Rett syndrome and Down syndrome
• Stem Cell Therapies in animal studies show neonates and some infants have potential for brain structural repair
• Transgenics have potential in people with Sanfilppo syndrome A
• Small molecule therapies such as histone Deacetylase Inhibitors may have uses in people with Rubinstein-Taybi syndrome and Fragile X

Conclusion and comment

Whilst the review authors do not attempt a systematic review, the paper is a meta-commentary of future directions of potential therapeutic options. In order for the benefits to be realised, continued research is needed on the genetics, epigenetics and aetiology of the causes of learning disabilities.

When a specific diagnosis is identified it will need to be coded in clinical systems, particularly General Practitioner systems in the UK, so that if therapeutic options do emerge these can be offered to people with a learning disability.

The review authors feel that a substantial breakthrough to improve cognitive function will rank amongst the major medical advances such as vaccination. I think this remains to be seen and we should continue to focus on increasing the wellbeing and health of people with learning disabilities and their carers.

However, we need to consider the potential wider ethical and psychosocial implications of having experimental treatments to offer with potential to give benefits as well as unknown harm.

Research of Investigational Medicinal Products (CTIMPs) in people with a learning disability is covered by Medicines for Human Use (Clinical Trials) Regulations 2004 and is specifically excluded from the Mental Capacity Act (2007) in England and Wales.

Research using medicinal products can seem outdated as essential parts of the Mental Capacity Act such as best interests decision making and involvement of Independent Mental Capacity Advocates (IMCAs) are not part of the consent process. Adverse event reporting in new pharmaceutical treatments often go undetected in early trials until widespread use of the medication is in place.

As many people with learning disabilities have no known cause for their condition, new therapies that are seen to improve cognitive performance generally may be utilised by parents of children without learning disabilities.

New treatments may be more effective the earlier they are administered and this may include treating in utero during pregnancy. Despite this and other potential issues, I feel cautiously optimistic that novel treatments will emerge to help the lives of people with learning disabilities. We will keep you informed about new research in this area as it is published.

Links

Picker, J. D. and Walsh, C. A. (2013), New innovations: Therapeutic opportunities for intellectual disabilities. Ann Neurol., 74: 382–390. doi: 10.1002/ana.24002

Braddock D. Braddock D.Public spending for disability in the United States: 1997–2006. Boston: Federal Reserve Bank of Boston. Paper presented at: Conference on Housing for People with Disabilities; February 4–5, 2010; Washington, DC.