Ethical issues in genetic testing for Alzheimer's disease: lessons from Huntington's disease.

This article discusses an ethics research project in predictive testing for Huntington's disease (HD) and the relevance of the findings for genetic testing for Alzheimer's disease (AD). Participants were videotaped during their pre- and posttest counseling sessions, as well as when the results were given. Half of these were then interviewed in their homes. Changes that accompanied the receipt of decreased risk suggested that counseling as well as the genetic information led the participants through a rite of passage. The most significant changes seemed to be in relation to other family members. Application to persons at risk for AD needs to be qualified, since persons at risk for AD will not usually have as well developed a sense of "family risk," and are less likely to receive as definite a reduced risk. In diagnostic testing for AD, a substitute decision-maker will often be involved. An unavoidable result is that some of the related substitute decision-makers will receive results which may have, or be mistaken to have, predictive value. Substitute decision-makers must therefore be included in genetic counseling, and the psychosocial effects of their participation must be evaluated.