19 July 2009
ByAppeared in BioNews 517
Findings published last week suggest that people are not troubled upon learning they are at higher risk of developing Alzheimer's disease. Writing in the New England Journal of Medicine, researchers at the Boston University School of Medicine, US, led by Dr Robert Green, measured participants' anxiety levels following results of a genetic test. The paper arrives amidst debate on how harmful direct-to-customer genetics testing – offered by companies such as 23andMe and DeCodeMe – might actually be to individuals.
The study involved 162 people averaging 50 years of age, who had a parent with Alzheimer's disease. One third (non-disclosure group) were not given the results of the genetic test. The remainder (disclosure group) were told whether or not they carried a variant of the apolipoprotein E gene – ApoE4 – that is associated with increased risk of developing the condition. Questionnaires were issued to score subsequent anxiety, depression and distress. There was little difference measured between the disclosure and non-disclosure groups, and within the latter, there was only slightly more distress observed for those who tested positive for APoE4 than those who didn't. The moderate disparity was only short-lived, as both positive and negative appeared balanced at six months and one year later.
‘Subjects were not immune to the negative implications of learning that they had an increased risk, but these feelings were not associated with clinically significant psychological distress', Dr Green points out.
The results are at odds with a common concern that such genetic testing might cause more harm than good when a condition is neither preventable nor treatable. In many cases – and Alzheimer's is a good example – the presence of variant ‘X' is not an assurance of developing a disease, nor is absence a reprieve. APoE4 and a family history of Alzheimer's generally mean people have greater than 50 per cent chance of the disease by the age of 85. Yet non-carriers with a family history have between 30 and 35 per cent chance.
Drs Rosalie and Robert Kane, researchers at the University of Minnesota, US, writing in an editorial accompanying the paper, suggest there exists an important caveat to the study. Participants in the study were probably ‘sufficiently indifferent to the potential test results', they write, ‘and thus are not representative of those who have a strong perceived need to know or need not to know'. Furthemore, the study was prefaced by a counselling session for all participants, to better prepare them for results.