Impact of Presymptomatic Genetic Testing for Hereditary Ataxia and Neuromuscular Disorders: Where is the Evidence?

In their study on the impact of presymptomatic genetic testing for neurogenetic disorders, Smith et al¹ found that 13 (33%) of 39 individuals reported elevated anxiety levels during follow-up, from which they conclude that anxiety may persist in some persons with positive or negative test results. However, a closer look at their data reveals that these individuals had elevated anxiety scores at different follow-up assessments, since 10 (26%) of 38 individuals reported elevated anxiety levels immediately after testing, and 5 (21%) of 24 at 1-year and 7 (39%) of 18 at 2-year follow-up. Although these percentages of patients with elevated anxiety levels are substantial, they do not provide evidence for a long-term impact of genetic testing. The response rates at the follow-up assessments were 76%, 48%, and 36%, and it is not reported whether these were representative samples of the 50 participants who entered the study.

Notwithstanding, there is another indication that genetic testing may have an impact and that is found at the lower end of the intrusion and avoidance scales: immediately after testing, 8 (20%) of 41 participants scored 0 on the intrusion scale and 11 (28%) of 39 scored 0 on the avoidance scale (Figure 1, Smith et al).¹ Zero scores suggest the absence of psychological distress, but immediately following genetic testing such low scores seem too good to be true. Zero scores require that all items be responded with “not at all,” including “Any reminder brought back feelings about it” and “I thought about it when I didn’t mean to,” which are exemplary items of the intrusion scale, and “I tried not to think about it” and “I stayed away from reminders of it,” which illustrate the avoidance scale. When something momentous happens, these thoughts and feelings likely occur at least “rarely,” if not “sometimes” or “often.” In such situations, 0 scores on mental health questionnaires are more likely an illusion of good psychological health, resulting from a defensive denial of distress.² Where minor illusions may be adaptive for mental health and well-being,³ the denial of distress increases the risk of psychosomatic complaints.² Studies on the impact of genetic testing should therefore also be alert to responses at the very lower end of psychological scales.

Correspondence: Dr Janssens, University Medical Center Rotterdam, Department of Public Health, PO Box 1738, 3000 DR, Rotterdam, The Netherlands (a.janssens@erasmusmc.nl).