The role of psychiatry in genetic prediction programmes for Huntington ' s disease

psychiatrists are involved in its management (Roccatagliata, 1979; Folstein, 1989; Harper, 1991; Watt & Seller, 1993). More recently, new opportunities have become available for psychiatric intervention. Programmes for presymptomatic testing for HD fTyler et cd, 1992) have since 1983 required help with prediction and management of dysfunctional reactions to test results (e.g. suicidal behaviour), diagnosis and management of conventional psychiatric disorder, and research. More recently, psychiatrists are also being offered the opportunity of becoming members of newlyformed 'brain repair teams' where they will be

Psychiatric disorder is a central clinical component of Huntington's disease (HD) and psychiatrists are involved in its management (Roccatagliata, 1979;Folstein, 1989;Harper, 1991;Watt & Seller, 1993).More recently, new opportunities have become available for psychiatric intervention.Programmes for presymptomatic testing for HD fTyler et cd, 1992) have since 1983 required help with prediction and management of dysfunctional reactions to test results (e.g.suicidal behaviour), diagnosis and management of conventional psychiatric disorder, and research.More recently, psychiatrists are also being offered the opportunity of becoming members of newlyformed 'brain repair teams' where they will be expected to help with the assessment, selection, and preparation of patients for cell transplantation, and also act as stress specialists.It seems clear that such demands may challenge traditional psychiatric skills, concepts, and measuring instruments.This short paper deals only with psychiatric intervention in pre-symptomatic testing which can be clinical or research-related (Fig. 1).

Clinical interventions
Clinical involvement concerns the prediction of post-test negative reaction and the diagnosis and management of psychiatric disorder in 50% risk candidates.The former concerns the search for predictors (in mental state, personality, past history, etc.) of dysfunctional outcome to positive or negative test results (Martindale, 1987).In most cases, such indicators must be detected in subjects who can be described as 'normal' from the psychiatric point of view.There is not yet much evidence that traditional indicators such as impulsivity, intro-punitiveness, tendency to depression, and previous suicidal attempts are of particular use in this field.

Fig. L Psychiatric intervention in pre-symptomatic testing which can be clinical or research-related
After genetic testing, candidates fall into a carrier or a non-carrier category.From the psychiatric viewpoint, the former may be asymptomatic, have conventional (ICD-10) psychiatric disease, or show 'odd behaviours' which do not fit into any ICD-10 category (This group will be discussed later).Conventional psychiatric disease in carriers may be theoretically divided according to whether it is related to HD or 'coincidental' (e.g.major depression may be a chance association of HD).In practice, this separation is difficult to make but the distinction remains important from the clinical and research viewpoints.The group in whom psychiatry and HD are related can in turn be (theoretically) divided according to whether the psychiatric disorder is dependent upon the specific changes of HD or is 'reactive' (e.g.brought about by a pathological HD environment).Non-carriers can be also psychiatrically normal or abnormal, and the latter sub-divided into those whose disorder is 'reactive' to being brought up in a HD environment and those whose mental disorder is but a chance association.

Assessments
The assessment of pre-symptomatic subjects is carried out in the conventional way and should lead when applicable to an ICD-10 diagnosis.In the Cambridge HD clinic the procedure lasts about 90 minutes, roughly divided into 40 minutes for the interview, 40 for computerised testing, and about 10 to interview relatives.It is hoped that the psychiatrist would also play a role in the analysis and resolution of the ethical issues that may arise in genetic testing.The general principles governing this field have been well studied (Mastromauro et oL, 1987;Smuri & Weaver, 1987;Kessler et al. 1987;Meissen & Berchek, 1987;Shaw, 1987;Ever-Kiebooms et oÃ-, 1987) valid) enough.The answer to this will depend on the objectives of the research (i.e. the type of 'caseness' it requires).For example, if it is to establish the prevalence of conventional psychiatric disorder then the usual approach may suffice; even then the fact that reports of rates of psychiatric morbidity in HD range from 25 to 80% (Harper, 1991) seems to suggest that the conventional approach is not working well.If, however, the objective of the research is to find new behavioural (or other) markers of gene-carrying status (in apparently asymptomatic subjects) then the conventional assessments will be singularly unhelpful.For example, it has been suggested that gene carriers show since childhood subtle oddities of behaviour.A mother may say that an HD patient was behaviourally 'different' and that she 'knew' that he/she was going to develop the disease.Such claims can, of course, be rejected as retrospective falsification, but it is also possible that they do reflect some real change.Whatever this change might be, it will need to be described anew as it is likely to differ from any conventional 'symptom'.
The fact that such odd behaviours have not yet been fully described can be explained in a number of ways.
(a) They may be faint conventional symptoms and hence not within the resolution power (sensitivity) of conventional instruments.(b) They may be forms of experience or behaviour which are different in quality to conventional symptoms and hence are difficult to describe: for example, it is not uncommon for subjects suffering from neurological disorder to report strange experiences for which the psychiatrist has no name; these reports may be ignored altogether or forced into a known category (Berrios & Samuel, 1987) intro-and extra-punitiveness, depersonalisation-like experiences, increases in vague somatic complaints, impulsivity, dissociation between spontaneous and reactive behaviours, etc.) so that more sensitivity and fine-grain can be achieved.General instruments such as the AMDP (Guy & Ban, 1982) are based on an 'open' view of psychopathology and are particularly useful in this regard.Individual scales for symptoms (as opposed to diseases) are also beginning to appear.In addition, an attentive listening to the descriptions and experiences of testÃ©es should help to identify some of these new 'symptoms'.The longitudinal mapping of behaviour is even harder but may prove to be the only way of eventually finding specific psychopathological markers for HD.