The number of inherited disorders and risk factors that can be detected through genetic testing is increasing rapidly, and genetic testing may soon become a common component of routine medical care. Is behavioural medicine ready? For the first time, a sophisticated understanding of gene-environment interactions as manifested in the interactions among an individual's genetic predispositions, behaviour, and environment seems within reach. Rather than diminishing the role of behavioural science, advances in molecular medicine highlight the centrality of behaviour both in disease etiology and in the translation of science into practice.
This paper is systematic review of the literature on the individual impacts of genetic diagnosis in behavioural and psychological terms. It draws from papers on these topics and cites their studies extensively. The upshot is that carrier and predictive testing may have effects on anxiety and depression, but that there is genetic stigmatization. Prenatal testing may lead to increased premature termination of pregnancies.
The subset of psychological issues and processes that are most salient within the clinical genetics context has evolved alongside advances in biotechnology. Prenatal testing and carrier testing were among the first services offered, affording an opportunity for individuals to learn whether they had transmitted an altered gene to their offspring. As these tests provided information about the risk to the fetus, the focus of counseling tended to be on reproductive decision-making. More recently, genetic testing is being applied to detect personal susceptibility to disease, shifting the focus of counseling to personal risk reduction. The hope is that awareness of genetic risk will enhance informed medical decision making by physicians and patients alike. However, there may also be psycho- logical and social risks of genetic testing that should be considered, regardless of the potential medical benefits provided by testing. It is in this consideration of the entire breadth of the potential costs and benefits that psychologists can play a critical role. Both researchers and clinicians can assist patients, families, physicians, and policymakers as they grapple with the complex task of integrating genetic information into their professional practice and everyday lives (Lerman et al., 2002).
Psychological Effects of Carrier Testing
In one of the earliest reports of the impact of carrier testing, investigators studied the implementation of a sickle-cell disease carrier screening program in a community where 23% of the population were gene carriers and about 1% of infants were born with sickle-cell disease. The community's custom of arranging marriages provided the opportunity to offer counseling aimed at avoiding matings between carriers. A 7-year follow-up descriptive evaluation indicated that notification of carrier status resulted in anxiety, embarrassment, and an inferior social status, particularly among women. In fact, 20% of parents reported that they requested that their noncarrier children not marry a carrier, even though such an arrangement would not result in any offspring with the disease. In a related study, carriers and noncarriers did not report differences in self-image. However, noncarriers were found to have more negative attitudes about sickle-cell carrier status than carriers, suggesting the potential for social stigmatization.
A more recent qualitative study examined adults' experiences with carrier testing for four disorders: cystic fibrosis, Tay-Sachs disease, Duchenne muscular dystrophy, and Fragile X syndrome. Results suggested that noncarriers experienced relief and a general sense of well-being toward their future childbearing. However, carriers reported feelings of hopelessness regarding the health of their offspring.
As is evident from this brief review, few studies of carrier testing have used validated tools for assessing psychological outcomes. However, in a prospective study of general-population cystic fibrosis screening in Great Britain, investigators compared carriers and noncarriers in terms of anxiety levels (as measured by the State -- Trait Anxiety Inventory [STAI]). Carriers reported small but statistically significant increases in anxiety immediately following testing. Although most carriers did not report sustained anxiety, those who still intended to have children reported some anxiety at 6-month follow-up. One study also reported on the psychological status of cystic fibrosis mutation carriers. A modified version of the STAI administered after genetic counseling did not reveal differences in anxiety between carriers and a matched control sample of test decliners (Lerman, et al., 2002).
Psychological Effects of Predictive Testing
Huntington's disease. The first longitudinal study of HD testing was initiated in British Columbia in 1986. The results indicated that immediately after learning test results (7 -- 10 days), the in- creased risk group reported decreased scores on the General Well- Being Scale, but little change on measures of distress (General Severity Index from the Symptom Checklist 90) and depressive symptoms (Beck Depression Inventory [BDI]) from baseline. Those who had a decreased risk reported increases on the General Well-Being Scale, along with reductions in the General Severity Index and the BDI. By 6 months posttest, the difference between groups was limited to scores on the General Well-Being Scale, and at the 1-year posttest measurement the groups did not differ significantly on any of the three measures. This study also followed 40 individuals who did not receive risk-altering information. A subset (n =23) of these individuals declined testing, whereas the others (n =17) were told that testing would not be informative for them. By the 1-year follow-up, this group had higher levels of depressive symptoms and lower well- being scores than the increased or decreased risk groups.
Studies of testing for HD have also examined predictors of psychological responses to testing. Another study reported data from carriers and noncarriers approximately 6 months after receiving genetic test results. Precounseling HD-related stress symptoms (based on the Impact of Event Scale [IES]) predicted poorer adjustment. Other studies evaluated participants in an HD testing program using the BDI and the BHS. Baseline distress scores were the best predictor of postcounseling distress, and genetic status was only marginally predictive (Lerman et al., 2002).
Cancer susceptibility. A few large-scale longitudinal studies have begun to yield data on the psychological effects of genetic testing for cancer susceptibility. In a study of members of hereditary breast cancer families, noncarriers of BRCA1 mutations reported significant reductions in depressive symptoms (as defined by the CES -- D scale) and functional impairment (as measured by two scales from the Medical Outcomes Study), compared with carriers and those who chose not to be tested. However, carriers did not show overall increases from baseline to follow-up in measures of depressive symptoms and functional impairment. In another study of BRCA1 testing, carriers reported higher levels of test-related distress (as measured by the IES) than noncarriers approximately 1 -- 2 weeks after learning test results. Similar to this study, carriers did not exhibit increases in anxiety (as defined by scores on the STAI) from baseline to follow-up. In this study, carrier women who had never experienced cancer or cancer-related surgery reported higher levels of test-related distress (Lerman et al., 2002).
Although these studies did not provide evidence for adverse effects of testing, analyses have been conducted to identify sub- groups of individuals that might be more psychologically vulnerable. Other studies classified their hereditary breast cancer family members into low-moderate (two lowest tertiles) and high-stress categories based on their scores on the Intrusion subscale of the IES. The highest levels of depression symptoms 1 month after testing (based on CES -- D scores) were reported by individuals with high stress at baseline who decided not to get tested. In this subgroup, 26% reported symptoms consistent with depression at baseline, and by 1 month, this number had increased to 47%. More recently, a study reported that testing participants who underestimated the emotional impact of testing were more likely to experience distress 6 months after receiving their results (Lerman et al., 2002).
A study addressed the psychological effects of genetic testing for familial adenomatous polyposis, a form of colon cancer first characterized by the formation of hundreds of polyps in adolescence and early adulthood. Investigators surveyed tested children and their parents before and 3 months after testing using the Children's Depression Inventory or the Reynolds Adolescent Depression Scale and Children's Manifest Anxiety Scale. Children's depression levels remained in normal ranges after testing. How- ever, mutation-positive children with affected mothers had significantly higher follow-up depression scores. Further, all children with affected mothers had increased anxiety scores.
Behavioral Outcomes of Predictive Testing
Although initial studies suggest that genetic-testing decisions were motivated by the desire to gain information about surveillance options, little is known about the actual ways in which genetic testing influences behavior. In one longitudinal study, none of the 41 BRCi carriers reported having a prophylactic mastectomy by 1-year follow-up, but 17% were considering it. It is interesting to note that 43% of the eligible carriers reported having had an oophorectomy within the year since learning their test results, with most of the other carriers considering it. There were no differences in reported mammography use between carriers and noncarriers among women over 40 years old (81% of carriers and 73% of noncarriers reported a mammogram within the year). However, younger carriers (aged 25 -- 39) were more likely than younger noncarriers to have…