Knowledge About Dementia Predisposition Reduces Cognitive Performance
December 23, 2013
Ethicists and others have been concerned that the disclosure of genetic information to patients might have negative consequences. The suspicion has been that negative effects, say becoming depressed, are particularly likely when people are being informed about predispositions to diseases that are not currently preventable or easily treatable. However, the small number of studies to date that have looked at this possibility have had difficulty demonstrating any long-term negative effects on mood or anxiety—the consequences thought most likely. A new study, though, suggests that previous research may have been looking in the wrong places to detect adverse consequences of genetic knowledge.
In a paper published online by the American Journal of Psychiatry, researchers from Butler University in Indiana and the University of California, San Diego examined the effects on cognitive performance of telling people that they carry a gene variant predisposing them to Alzheimer’s disease. A group of 144 cognitively normal, older adults were divided into two subgroups: one subgroup was told whether they carried the variant in question (which scientists call ApoE4) and one (a comparison subgroup) was not. In the subgroup that was told about their genetic status, participants who were told that they were ApoE4 carriers rated their cognitive status more poorly than those who were told that they did not have an ApoE4 variant. Moreover, when their cognitive performance was tested, participants who knew that they were ApoE4 carriers did significantly worse than participants in the comparison group who also carried an ApoE4 gene, but were not told about it.
The researchers suggest that their findings are consistent with other studies that have shown that older people who expect to perform more poorly on memory tasks in fact do worse on the tests, and that their performance can be improved merely by changing their expectations. Here, telling participants that they had a genetic propensity to develop Alzheimer’s disease in the future lowered their estimates of how good their memory was at present and resulted in poorer performance, perhaps due to reduced effort.
As the field of genetics struggles with determining which genetic information should be tested for and disclosed to people without apparent disorders, this study provides a useful caution about the potential negative effects of disclosure. Whether data about predispositions to other kinds of disorders could have similar effects is unclear. But one can’t help wondering whether a person’s being told, for example, that he or she is at risk for cardiac disease in the future might affect the person’s perception of their current physical condition and thereby discourage them from engaging in the very kind of physical exercise that might help to stave off a heart attack. This study opens up a set of very important questions for future research.