Predictive testing for Huntington disease: nonparticipants compared with participants in the Dutch program.

Attitudes toward predictive testing programs, in individuals who choose not to undertake the test (i.e., nonparticipants), may be influenced by fears of an unfavorable result. The reasons not to participate in predictive testing programs for Huntington disease (HD) were studied in members of the Dutch Huntington Association who were at 50% risk. They had completed the same baseline psychological questionnaires as had the participants in the Dutch DNA-testing program. The group of 34 nonparticipants was similar to the tested participants in the Dutch predictive testing program, with respect to average age (31.1 years), male:female ratio (1:2), the frequency of a stable relationship (70%), and level of education (67% had high school education or higher). Testing did not seem to be a realistic option for nonparticipants for improving their quality of life. In comparison with participants, nonparticipants had a significantly more pessimistic outlook on themselves and their futures. When asked to consider the possibility of an unfavorable result, nonparticipants expected more difficulties in their families; more problems for their children, their partners, and themselves; a lowered quality of life; and, more often, a depressive reaction. In their opinion, a favorable result would reduce the problems for their children but not for themselves, a result that was found more often in the nonparticipant than in the participant group. Nonparticipants learned about their being at risk for HD during adolescence (mean age 15.6 years), whereas participants did so in adulthood (mean age 22.7 years). The nonparticipants' attitude toward the test might be explained by the influence of HD in the adolescent's separation-individuation process and personality development. This finding could be relevant for future research and for the discussion about testing minors for delayed-onset disorders.