The conclusion was based on an analysis of 162 volunteers who took a blood test to see whether they had the e4 variant of the apolipoprotein E gene, which has been linked to an increased risk of Alzheimer's disease. Some volunteers got their results; others didn't. But members of both groups were equally likely to display signs of anxiety or depression, according to the study.
To approximate what they considered to be a more appropriate analysis, they compared the mental health scores of people who got their test results with the baseline scores of all the volunteers, which they argued was a closer approximation of the level of anxiety and depression in a truly untested group. In this analysis, there were "significant increases in depression" among those who were tested and got their results.
The study's original authors concede that their critics "raise an interesting point." But they defended their initial approach.
In a reply that was also published in the journal, they said their intent was to discern the psychological impact of learning one's genetic risk among people who really wanted to know. Presumably, untested people are not that curious, so they're not the right control group, they said.