Behavioural changes are an integral feature of Huntington‘s disease. Personality changes are often already reported early in the course of the disease. Frequently reported behavioural symptoms comprise depression, anxiety, irritability, apathy, compulsive behaviour and thoughts and - to a lesser extent – psychotic symptoms. Severity and occurrence of these symptoms vary greatly as well as their development during disease progression. Although there is currently no treatment that is able to cure HD, many of these behavioural symptoms can be treated adequately with either medication, or behavioural psychotherapy or a combination of both.
 
Research into identifying a successful treatment for HD is ongoing. In order to test treatments for their effectiveness it is important that assessments are sensitive and valid for measuring behavioural symptoms, as well as their changes over the course of HD. Additionally the symptomatic treatments used for behavioural features are insufficiently documented. The Behavioural Working Group aims at the development of new assessment tools, improvement of existing tools and a better documentation of symptomatic treatment options.

The primary aims of the EHDN Behavioural Working Group are:

• Development of new more sensitive behavioural assessment tools to be used in the Registry project.

• To improve available behavioural assessment tools

• Introduce certification for behavioural assessment

• Provide better documentation of use and efficacy of available symptomatic treatment options.

A short behavioural assessment for Registry has been developed. The assessment is shorter and has clearer scoring criteria and is based on the Psychiatric Behavioural assessment and the UHDRS behavioural assessment. With the help of the working group and other EHDN members, this assessment has been translated into the various European languages in EHDN. Furthermore a workshop for training psychiatric raters in the use of this short behavioural assessment. At least two raters of each language have completed this workshop and are those who will be responsible for the training of other psychiatric raters in their country. At the moment designs for validity of the PBA-short in English and other (as many as possible) languages are under development. A suitable certification system for psychiatric/behavioural raters within the Registry project is being developed as well.

The working group is also active in executing validity studies of available assessments that are used for measuring behavioural symptoms, specifically for use in HD. An example is the validation of the HADS and BDI / BDI II for measuring depression in HD.

Study protocols for data mining projects of behavioural data in the Registry database are currently being developed and will soon be executed.

In order to find out more about available treatment options for behavioural symptoms, protocols for Open Label Efficacy (OLE) studies for Apathy, Irritability and Depression are developed. Assessments for these specific symptoms are identified and are to be translated into the various languages.

The Behavioural Phenotype Working Group currently has approximately 30 active members and an additional estimated 45 associate members. Membership is open to scientists and clinicians with an interest in the Behavioural and psychiatric aspects of HD. The group meets twice a year, of which usually one time is at the EHDN plenary meeting and one on another occasion most often in Leiden, the Netherlands. The group maintains contact by e-mail communication between the face to face meetings. During these meetings the status and progress of Working Group activities are discussed and members of the working group have the opportunity to present their own projects as well as to propose collaborative working group projects.
Each meeting a representative of the Huntington’s Study Group behavioural working group is invited to give an update of their activities, which also opens possibilities for more global collaboration.
Members of the working Group have access to the working group area on the EHDN website and active members can also upload material at this area for optimal documentation.