Perhaps you should skip that genetic test for Alzheimer’s risk after all

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Last year, we wrote about a study in the New England Journal of Medicine that asked whether the children of Alzheimer’s patients should find out whether they were genetically predisposed to the same fate. Defying conventional wisdom, the researchers concluded that people who learned their genetic status could take the information in stride – as long as they received appropriate genetic counseling.

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.

Two researchers from New York University had their doubts. In a letter published in this week’s issueof the journal, they point out that people who got their APOE e4 test results should have been compared with people who were never tested at all. After all, everyone who took the blood test had time to think about the possibility that they had bad genes, so anxiety and depression could have been high even among volunteers who never got their test results.

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.

-- Karen Kaplan