Most people who undergo genetic testing and counseling related to Parkinson’s disease are satisfied with their experience and feel no substantially adverse psychological effects, a study reported.
However, its findings also indicated that people with diagnosed Parkinson’s, or in whom Parkinson’s-linked mutations are identified, are more likely to be unsatisfied and feel uneasy, particularly about passing the disease to future generations.
The study, “Outcomes of genetic test disclosure and genetic counseling in a large Parkinson’s disease research study,” was published in the Journal of Genetic Counseling.
Mutations in certain genes, such as LRRK2 and GBA, are associated with an increased risk of Parkinson’s disease. As genetic testing becomes more accessible, more people are able to know whether they have Parkinson’s-associated mutations in these genes — sometimes long before symptoms might develop.
Finding out you carry a Parkinson’s-associated mutation can affect your psychological well-being. Because little research into the psychological effects of genetic testing for Parkinson’s has been done, scientists at Indiana University explored the ramifications of such testing.
“We describe the psychological impact of disclosure of PD [Parkinson’s disease] genetic test results, and satisfaction with genetic counseling in a large cohort of research participants with PD, or who were at an increased risk of developing PD,” the researchers wrote.
They analyzed data for 875 people, which was collected as part of the Widespread Recruitment Initiative (WRI). This Indiana University program identifies and recruits people for the Parkinson’s Progression Markers Initiative, an ongoing observational study seeking to identify new markers of disease progression.
As part of the WRI process, individuals underwent genetic testing for Parkinson’s-associated mutations in LRRK2 and GBA. Results were then reviewed with a licensed genetic counselor during over-the-phone counseling sessions that averaged about half an hour’s time.
About a month after the counseling session, patients were emailed one of two surveys: a modified version of the Multidimensional Impact of Cancer Risk Assessment (MICRA) to assess the psychological impact of genetic testing, or the Genetic Counseling Satisfaction Survey (GCSS) to measure patient satisfaction with genetic testing.
In the MICRA survey, references to “cancer” were replaced with “Parkinson’s disease.” Scores on the MICRA range from 0 to 95, with higher scores indicating a greater negative psychological effect. Scores on the GCSS range from 6 to 30; higher scores indicate greater satisfaction.
Most (95%) of the survey responders were of Ashkenazi Jewish ancestry, a population with a high incidence of Parkinson’s. Respondents’ mean age was 65; 42% were male, and 23% were diagnosed with Parkinson’s.
Genetic testing revealed Parkinson’s-linked mutations in 132 (15%) of these people: 52 had mutations in LRRK2, 75 in GBA, and five in both genes.
The mean total MICRA score for the study population was 14.6. Individuals with diagnosed Parkinson’s had significantly higher scores (more adverse psychological effects) than those without a diagnosis. Additionally, people in whom genetic testing revealed a Parkinson’s-associated mutation had significantly higher scores than those with no identified mutation.
Similar trends were seen in the various subscales of the MICRA. Of note, people who were mutation-positive were significantly more likely to express worry or guilt about passing Parkinson’s to their children than were mutation-negative individuals.
“Respondents who carried a pathogenic variant [Parkinson’s-linked mutation] appeared to be more worried about implications to their family members than those who tested negative, which may explain some of the increased psychological effects,” the researchers wrote.
The mean GCSS score was 27.1. Similar to the MICRA scores, those with diagnosed Parkinson’s had significantly lower GCSS scores (lesser satisfaction) than those without, and individuals positive for Parkinson’s-associated mutations had significantly lower scores than those without mutations.
“This is the first study to provide evidence that most participants are satisfied with disclosure of genetic test results and genetic counseling for [Parkinson’s disease] by board-certified and licensed genetic counselors. However, those with [Parkinson’s disease] and/or who carried a pathogenic variant were less satisfied and had less favorable psychological outcomes than those without [Parkinson’s disease] or without an identified variant,” the researchers concluded.
They noted a need for more research into the psychological impact of genetic testing for Parkinson’s, and into possible strategies for lessening the psychological burden on patients.
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