Schizophrenia Flashcards
Reliability and validity in diagnosis and classification
RELIABILITY: LACK OF INTER-RELIABILITY: Despite the claims for increased reliability in DSM-III, over 30 years later there is still little evidence that DSM is routinely used with high reliability by mental health clinicians. Whaley (2001) found inter-reliability correlations in the diagnosis of schizophrenia as low as 0.11. Further problems with the inter-reliability of the diagnosis of schizophrenia are illustrated in the Rosenhan study. This suggests that, because psychiatric diagnosis lacks some of the more objective measures enjoyed by other branches of medicine it inevitability faces additional challenges with inter-rater reliability.
UNRELIABLE SYMPTOMS: for a diagnosis, only one of the characteristic symptoms is required ‘if delusions are bizarre’. However, this creates problems for reliability of diagnosis. When 50 senior psychiatrists in the US were asked to differentiate between ‘bizarre’ and ‘non-bizarre’ delusions, they produced inter-rater reliability correlations of only around 0.40 (Mojtabi and Nicholson, 1995). The researchers concluded that even this central diagnostic requirement lacks sufficient reliability for it to be a reliable method of distinguishing between schizophrenic and non-schizophrenic patients.
A COMMENT ON CULTURAL DIFFERENCES IN THE DIAGNOSIS OF SCHIZOPHRENIA: research (e.g Barnes, 2004) has established cultural, and radical, differences in the diagnosis of schizophrenia. However, the prognosis for members of ethnic minority groups may be more positive than for majority group members. The ethnic culture hypothesis predicts that ethnic minority groups experience less distress associated with mental disorders because of the protective characteristics and social structures that exist in these cultures. Brekke and Barrio (1997) found evidence to support this hypothesis in a study of 184 individuals diagnosed with Schizophrenia or a schizophrenia spectrum disorder. This sample was drawn from two non-white minority groups (African Americans and Latinos) and a majority group (white Americans). Consistent with the predictions of the ethnic culture hypothesis, they found that non-minority group members were consistently more symptomatic than members of two ethnic minority groups.
RESEARCH SUPPORT FOR GENDER BIAS IN DIAGNOSIS: Loring and Powell (1988) found evidence of gender bias among psychiatrists in the diagnosis of schizophrenia. Randomly selected 290 male and female psychiatrists to read two case vignettes of patients’ behaviour. These psychiatrists were asked to offer their judgement using standard diagnostic criteria. When the patients were described as ‘males’ or no information was given about their gender, 56% of psychiatrists gave a diagnosis of schizophrenia. However, when the patients were described as ‘female’ only 20% were given a diagnosis. This gender bias was not as evident among the female psychiatrists, suggesting that diagnosis is influenced not only by the gender of the patient but also the gender of the clinician.
CONSEQUENCES OF CO-MORBIDITY: a number of studies have examined single co-morbidities with schizophrenia, but these studies have usually involved only relatively small sample sizes. By contrast, Weber et al (2009) looked at nearly 6 million hospital discharge records, finding evidence of many co-morbid non-psychiatric diagnoses. Many patients with a primary diagnosis were also diagnosed with medical problems including asthma, hypertension and type 2 diabetes. The authors concluded that the very nature of a diagnosis of a psychiatric disorder is that patients tend to receive a lower standard of medical care, which in turn adversely affects the prognosis for patients with schizophreni.
DIFFERENCES IN PROGNOSIS: in the same way that people diagnosed as schizophrenic rarely share the same symptoms, likewise there is no evidence that they share the same outcomes. The prognosis for patients diagnosed with schizophrenia varies with about 20% recovering their previous levels of functioning. 10% achieving significant and lasting improvement and about 30% showing some improvement with intermittent relapses. A diagnosis of schizophrenia, therefore, has little predictive validity- some people never appear to recover from the disorder, but many do. What does appear to influence outcome, therefore, is more to do with gender (Malmberg et al, 1998) and psychosocial factors such as social skills, academic achievement and family tolerance of schizophrenic behaviour (Harrison et al, 2001).
Biological explanations for schizophrenia
GENETIC FACTORS - MZ TWINS ENCOUNTER MORE SIMILAR ENVIRONMENTS: a crucial assumption underlying all twin studies is that the environments of monozygotic twins and dizygotic twins are equivalent. However, as Joseph (2004) points out, MZ twins are treated more similarly, encounter more similar environments and experience more ‘identity confusion’ (frequently being treated as the twins rather than as two distinct individuals) than DZ twins. This suggests that’s difference in concordance rates between MZ and DZ twins reflect nothing more than environmental differences that distinguish the two types of twin.
ADOPTEES MAY BE SELECTIVELY PLACED: an assumption of adoption studies is that adoptees are ‘not selectively placed’ i.e adoptive parents who adopt children with a schizophrenic biological parent are no different to adoptive parents who adopt children whose background is normal. One of the largest adoption studies of schizophrenia took place in Oregon (Heston 1966), where it was assumed that procreation by any person admitted to a mental hospital would produce offspring with an inherited tendency to ‘feel mindedness, insanity and degeneracy’. It is extremely unlikely that the children born to women with schizophrenia would have been placed into the same type of adoptive families as children without such a background (Joseph, 2004). This, coupled with other problems with twin and adoption studies, suggest we cannot accept their conclusion about the role of genetic in schizophrenia.
NEURAL CORRELATES- DOPAMINE HYPOTHESIS: EVIDENCE FROM TREATMENT: much of the evidence supporting the dopamine hypothesis comes from the success of drug treatments that attempt to change levels of dopamine activity in the brain. Leucht et al (2013) carried out a meta-analysis of 212 studies. They concluded that all the antipsychotic drugs tested in these studies were significantly more effective than placebo in the treatment of positive and negative symptoms, achieved by reducing the effects of dopamine. These findings also challenge the classification of antipsychotics into typical and atypical groupings because differences in their effectiveness were only small.
CHALLENGES TO DOPAMINE HYPOTHESIS: Noll (2009) claims there is strong evidence against both the original dopamine hypothesis and the revised dopamine hypothesis. He argues that antipsychotic drugs do not alleviate hallucinations and delusions in about one third of people experiencing these symptoms. Noll also points out that, in some people, hallucinations and delusions are present despite levels of dopamine being normal. This suggests that, rather than dopamine being the sole cause of positive symptoms, other neurotransmitter systems, acting independently of the dopaminergic system, may also produce the positive symptoms associated with schizophrenia.
SUPPORT FOR THE INFLUENCE OF GREY MATTER DEFICITS: support for the significance of grey matter deficits in schizophrenia comes from a meta-analysis by Vita et al (2012). They analysed the results of 19 studies. Patients with schizophrenia, compared with healthy controls, showed a higher reduction in cortical great matter volume over time. This pattern of grey matter reduction was specific to discrete cortical areas in the frontal, temporal and parietal lobes. This loss of grey matter was especially active in the first stages of the disease, consistent with the relatively early onset of schizophrenia (late teens/ early 20s).
IMPLICATIONS FOR TREATMENT: the importance of neural correlates for schizophrenia is that early intervention might prevent development of the later stages of this disorder. This concept of ‘treatment as prevention’ is seen in the North America Prodome Longitudinal study (Addington et al 2015) which uses a number of different assessments, including neuroimaging to predict who will develop psychoses such as schizophrenia. With a better understanding of how schizophrenia develops, researchers can detect loss of brain tissue early and treat at-risk patients before psychosis develops.
Psychological explanations (family dysfunction )
FAMILY RELATIONSHIPS: the importance of family relationships in schizophrenia was demonstrated in an adoption study by Tienari et al (1994). In this study, adopted children who had schizophrenic biological parents were more likely to become ill themselves than were children with non-schizophrenic parents. However, this difference emerged only in situations where the adopted family itself was rated as disturbed. This suggests that illness not only manifests itself under appropriate environmental conditions, therefore genetic vulnerability alone is not sufficient.
DOUBLE BIND THEORY: there is some evidence to support this. Berger (1965) found that schizophrenics reported a higher recall of double bind statements by their mothers that non-schizophrenics. However, other studies are less supportive. Lime (1974) measured patterns of parental communication in families with a schizophrenic child and found no difference when compared to normal families. Despite these inconsistencies in research support, Gibney (2006) claims that the real value of double bind theory is that it led to the development of family therapy. If interactions could be problematic and pathology producing, then they might also be organised more constructively and so become health producing.
INDIVIDUAL DIFFERENCES IN VULNERABILITY TO EE: now all patients who live in high EE families relapse, and not all patients who live in low EE homes avoid relapse. Research has found individual differences in stress response to high EE- like behaviours. Altorfer et al (1998) found ¼ of patients they studied showed no physiological responses to stressful comments from their relatives. Vulnerability to the influences of high EE may also be psychologically based. Lebell et al (1993) claims that how patients appraise the behaviour of their relatives is important. In cases where high EE behaviours are not perceived as being negative or stressful, patients can do well regardless of how the family environment is objectively rated. This shows that not all patients are equally vulnerable to high levels of expressed emotion within the family environment.
Psychological explanations (cognitive explanations )
SUPPORTING EVIDENCE FOR COGNITIVE MODEL OF SCHIZOPHRENIA: Sarin and Wallin (2014) found supporting evidence for the claim that the positives symptoms of schizophrenia have their origins in faulty cognition. Delusional patients were found to show various biases in their information processing, such as jumping to conclusions and lack of reality testing. Likewise, schizophrenic individuals with hallucinations were found to have impaired self-monitoring and also tended to experience their own thoughts as voices. A consequence of this is that a therapist can use this information when he or she chooses techniques for the treatment of patients.
SUPPORT FROM THE SUCCESS OF COGNITIVE THERAPIES: the claim that the symptoms of schizophrenia have their origin in faulty cognition is reinforced by the success of cognitive-based therapies. The effectiveness of CBT was demonstrated in the National Institute for Health and Care Excellence (NICE) review of treatments for schizophrenia. This review found consistent evidence that, when compared with treatment by antipsychotic medication, CBT was more effective in reducing symptom severity and improving levels of social functioning. This supports the view that faulty cognitions have an important causal influence in the development of schizophrenia.
AN INTEGRATED MODEL OF SCHIZOPHRENIA: a problem with the cognitive model is that it deals adequately with one aspect of the disorder (e.g cognitive impairment) but fails to explain or ignores other aspects (e,g social adversity). Howes and Murray (2014) addressed this problem with an integrated model of schizophrenia. Early vulnerability factors (e,g genes, birth complications etc) together with exposure to significant social stressors (e.g social adversity), sensitises the dopamine system, causing it to increase the release of dopamine. Biased cognitive processing of this increased dopamine activity results in paranoia and hallucinations and eventually the development of a psychosis. By putting the impact of life events at the centre of the process leading to schizophrenia, this model fits in with more recent research showing that exposure to significant social stressors is associated with a considerable increase in risk of developing this disorder.
Drug therapy
ANTIPSYCHOTICS VERSUS PLACEBO: support for effectiveness of antipsychotics comes from studies that have compared relapse rates for antipsychotics and placebos. Leucht et al (2012) carried out to a meta-analysis of 65 studies, published between 1959 and 2011, and involving nearly 6000 patients. Some of these patients were taken off their antipsychotic medication and given a placebo instead. The remaining patients remained on their regular antipsychotic. Within 12 months, 64% of those patients who had been given the placebo had relapsed, compared to 27% of those who stayed on the antipsychotic drug. This study clearly demonstrates the superiority of antipsychotic drugs compared to placebo in preventing relapse, although their use must be weighed against their side effects.
EXTRAPYRAMIDAL SIDE EFFECTS: typical antipsychotic drugs can sometimes produce movement problems for the patient. These are called extrapyramidal effects because antipsychotic drugs appear to impact on the extrapyramidal effects because antipsychotic drugs appear to impact on the extrapyramidal area of the brain, which helps control motor activity. The most common are Parkinson related symptoms so called because they resemble the features of the neurological disorder Parkinson’s disease. More than half of the patients taking typical antipsychotics experience these symptoms. When people take these drugs for an extended periods, a second type of extrapyramidal effect can occur. These side effects can be so distressing for the patient that other drugs have to he given to control them, or the patient may stop taking their antipsychotic medication completely.
ETHICAL PROBLEMS WITH TYPICAL ANTIPSYCHOTICS: recently in the US a large out-of-court settlement was awarded to a tar dive dyskinesia sufferer on the basis of Article 3 of the Human Rights Act 1988, which states that ‘no one shall be subjected to inhuman or degrading treatment of punishment’ (Chari et al 2002, cited in Ross and Read, 2004). This suggests that if side effects, deaths and psychosocial consequences were taken into account, a cost-benefit analysis of typical antipsychotics would most probably be negative.
ADVANTAGES OF ATYPICAL OVER TYPICAL ANTIPSYCHOTICS: atypical antipsychotics are claimed to have a number of advantages when compared to typical antipsychotics. A key advantages of atypical antipsychotics is that patients experience fewer side effects. Atypical antipsychotics, particularly newly developed drugs such as olanzapine ad quetipane, are less likely to produce the extrapyramidal effects commonly found with typical antipsychotics. As a result, patients are more likely to continue with their medication, which in turn means they are more likely to see a reduction in their symptoms.
ARE ATYPICAL ANTIPSYCHOTICS BETTER: the introduction of atypical antipsychotics led to claims of the superiority of these drugs over the older ‘typical’ antipsychotics. Crossly et al (2010) carried out a meta-analysis of 15 studies to examine the efficacy and side effects of atypical versus typical antipsychotics in the early-phase treatment of schizophrenia. They found no significant differences between atypical and tropical drugs in terms of their effect on symptoms but did note differences in the type of side effects experienced. Patients on atypical antipsychotics gained more weight than those on typicals, whereas those on typicals experienced more extrapyramidal side effects. They concluded there was no evidence for differences in efficacy between atypical and typical antipsychotics but there was a clear difference in the side effect profile.
MOTIVATIONAL DEFCITS: Ross and read (2004) argue that when people are prescribed antipsychotic medication, it reinforces the view there is ‘something wrong with them’. This prevents the individual from thinking about possible stressors that might be contributing to their condition. In turn this reduces their motivation to look for possible solutions that might alleviate these stressors and reduce their suffering. Read (2005) concludes that as human misery is largely inflicted by other people then the best solutions are usually human- rather than chemical or electrical- interventions.
Cognitive behavioural therapy
ADVANTAGES OF CBTp OVER STANDARD CARE: the NICE (2014) review of treatments for schizophrenia found consistent evidence that, when compared with standard care (antipsychotic medication alone), CBTp was effective in reducing rehospitalisation rates up to 18 months following the end of treatment. CBTp was also shown to be effective in reducing symptom severity and when compared with patients receiving standard care, there was some evidence for improvements in social functioning. However, most studies of the effectiveness of CBTp have been conducted with patients treated at the same time with antipsychotic medication. It is difficult, therefore, to assess the effectiveness of CBTp independent of antipsychotic medication.
EFFECTIVENESS OF CBTp IS DEPENDENT ON STAGE OF DISORDER: CBTp appears to be more effective when it is made available at specific stages of the disorder and when the delivery of the treatment is adjusted to the stage the individual is currently at. Addington and Addington (2005) claim that in the initial acute phase, self-reflection is not particularly appropriate. Following stabilisation of the psychotic symptoms with antipsychotic medication, however, individuals can benefit more from group based CBTp. This can help normalise their experience by meeting other individuals with similar issues. Research has consistently shown that it is individuals with more experience of their schizophrenia and a greater realisation of their problems that benefit more from CBTp.
LACK OF AVAILABILITY OF CBTp: despite being recommended by NICE as a treatment for people with schizophrenia, it is estimated that in the UK only one in 10 of those who could benefit get access to this form of therapy. This figure is even lower in some areas of the country. A survey carried out by Haddock et al (2013) in the North West of England found that of 187 randomly selected patients diagnosed with schizoprenia, only 13 (6.9%) had been offered CBTp. However, of those who are offered CBTp as a treatment for schizophrenia, a significant number either refuse or fail to attend the therapy sessions (Freeman et al 2013) thus limiting its effectiveness even more.
PROBLEMS WITH META-ANALYSES OF CBTp AS A TREATMENT FOR SCHIZOPHRENIA: one reason why meta-analyses in this area can reach unreliable conclusions about CBTp effectiveness is failure to take into account study quality. Some studies fail to randomly allocate participant to either a CBTp or control condition; others fail to mask the treatment condition for interviewers carrying out subsequent assessments of symptoms and general functioning. Nevertheless, despite such differences and failings, all such studies are grouped together for a meta-analysis. Juni et al (2001) concluded that there was clear evidence that the problems associated with methodologically weak trials translated into biased findings about the effectiveness of CBTp. In fact, Wykes et al (2008) found that the more rigorous the study, the weaker the effect of CBTp.
THE BENEFITS OF CBTp MAY HAVE BEEN OVERSTATED: more recent and methodologically sound meta-analyses of the effectiveness of CBTp as a sole treatment for schizophrenia suggest its effectiveness may actually be lower than originally thought. One recent large scale meta-analysis (Jauhar et al 2014) revealed only a ‘small’ therapeutic effect on the key symptoms of schizophrenia, such as hallucinations and delusions. However, even these small effects disappeared when symptoms were assessed ‘blind’ when assessors were unaware of whether the patient was in the therapy or control condition. This uncertainty over whether non-drug therapies such as CBTp really do offer superior outcomes to antipsychotic medication has led to conflicting recommendations even within the UK (Taylor and Perera 2015). In England and Wales, NICE (2014) emphasise non-drug therapies such as CBTp whereas in Scotland, SIGN (2013) places more emphasis on antipsychotic medications.
Family therapy
WHY IS FAMILY THERAPY EFFECTIVE: improvements in mental state and social functioning found in the pharaoh et al study may not be a direct result of family therapy. The main reason for its effectiveness may have less to do with any improvements in these clinical markers and more to do with the fact that it increases medication compliance. This suggests the main benefit of this therapy is that it makes people more likely to comply with their medication regime, which then leads to improvements in their mental state and social functioning.
A METHODOLOGICAL LIMITATION: LACK OF BLINDING: In the Pharoah et al meta-analysis, methodological quality was compromised in those studies where Ranters were not ‘blinded’ to the condition to which participants had been allocated. Ten of the 53 studies reported in the meta-analysis did not use any form of blinding; raters were aware of the types of treatment received by the participants they were rating. A further 16 did not mention whether blinding had been used. The lack of blinding is particularly problematic in studies with longer follow-ups where participants tend to unintentionally reveal the type of therapy they had received.
ECONOMIC BENEFITS OF FAMILY THERAPY: an additional advantage of family therapy is it has considerable economic benefits. The NICE review of family therapy studies (NCCMH 2009) demonstrated that family therapy is associated with significant cost savings when offered to people with schizophrenia in addition to standard care. The extra cost of family therapy is offset by a reduction in costs of hospitalisation because of the lower relapse rates associated with this form of intervention. There is also evidence that family therapy reduces relapse rates for a significant period after completion of the intervention. This means that cost savings associate with family therapy would be even higher.
IMPACT ON FAMILY MEMBERS: family therapy has been shown to improve outcomes for the individual with schizophrenia, but there may be an additional advantage that can have a positive impact on family members as well. Lobban et al (2013) analysed the results of 50 family therapy studies that had included an intervention to support relatives. 60% of these studies reported a significant positive impact on the intervention on at least one outcome category for relatives e.g coping and problem-solving skills, family functioning and relationship quality (including expressed emotion). However, the researchers also concluded that the methodological quality of the studies was generally poor, making it difficult to distinguish effective from ineffective interventions.
IS FAMILY THERAPY WORTHWHILE: a study by Garety et al (2008) failed to show any better outcomes for patients given sessions of family therapy compared to those who simply had careers but no family therapy. Individuals in both groups were found to have unexpectedly low rates of relapse, contrasting markedly with the rates found in the ‘no carer’ group. The researchers found that most of the careers in this study displayed relatively low rates of expressed emotion, which had may reflect widespread cultural changes in carers’ knowledge and attitude towards schizophrenia. Garety et al concluded that for many people family intervention may not improve outcomes further than a good standard of treatment as usual.
Token economy and management of schizophrenia
RESEARCH SUPPORT: Dickerson et al (2005) have provided research support for the effectiveness of token economies in a psychiatric setting. They reviewed 13 studies of the use of token economy systems I the treatment of schizophrenia. 11 of these studies gave reported beneficial effects that were directly attributable to the use of token economies. Dickerson et al concluded that overall these studies provide evidence of the token economy’s effectiveness in increasing the adaptive behaviours of patients with schizophrenia. However, many of the studies reviewed had significant methodological shortcomings that limited their impact in the overall assessment of token economies in this context.
DIFFICULTIES ASSESSING THE SUCCESS OF A TOKEN ECONOMY: comer (2013) suggests a major problem in assessing effectiveness of token economies is that studies of their use tend to be uncontrolled. When a token economy system is introduced into a psychiatric ward, typically all patients are brought into the programme rather than having an experimental group that goes through the token economy programme and a control group that does not. As a result, patients’ improvements can only be compared with their past behaviours rather than with those of a control group. This comparison, claims comer, may be misleading as other factors (increase in staff attention) could be causing patients’ improvements rather than token economy.
LESS USEFUL FOR PATIENTS LIVING IN THE COMMUNITY: although the token economy has shown to be effective in reducing negative symptoms for people with schizophrenia, it has only really been shown to work when in a hospital setting. Corrigan (1991) argues that there are problems administrating the token economy method with outpatients who live in the community. Within a psychiatric ward setting, inpatients receive 24-hour care and so there is better control for staff to monitor and reward patients appropriately. However, outpatients living in the community only received treatment for a few hours a day, so therefore the token method could only be used for part of the day. As a result, even if the token economy did produce positive results within the ward setting, these results may not be maintained beyond that environment.
ETHICAL CONCERNS: there are a number of ethical concerns concerning the use of the token economy programmes in psychiatric settings. In order to make reinforcement effective, clinicians may exercise control over important primary reinforcers such as food, privacy or access to activities that alleviate boredom. Patients may then exchange tokens if they display the target behaviours. However, it is generally accepted that all human beings have certain basic rights that cannot be violated regardless of the positive consequences that might be achieved by manipulating them within a token economy programme.
DOES IT ACTUALLY WORK?: researchers are yet to conclusively provide an answer to this question. Very few randomised trials have been carried out to support the claims made for the effectiveness of token economies in the management of schizophrenia. In an era of evidence-based medicine, this lack of support is considered unacceptable and so token economy programmes have fallen out of use in much of the developed world. McMonagle and Sultana (2000) suggest that the token economy may still be a potentially important treatment if such randomised trials could be carried out. They suggest that this is only likely to be possible in those developing countries where some form of token economy is still practised. This would provide an opportunity to finally answer questions about the effects of the token economy in the management of people with schizophrenia.
An interactionist approach
DIATHESIS MAY NOT BE EXCLUSIVELY GENETIC: most diathesis- stress models emphasise vulnerability in terms of genetic influences alone, which are assumed to cause neurochemical abnormalities that result in an increased risk for schizophrenia. This increased risk can result from brain damage caused by environmental factors Verdoux et al (1998) estimated that the risk of developing schizophrenia later in life for individuals who have experienced obstetric complications at birth (e.g prolonged labour causing oxygen deprivation) is four times greater than those who experience no such complications. These findings suggest that brain damage can play a role in the development of schizophrenia although can be caused by an already compromised foetus (Weinberger 1995).
URBAN ENVIRONMENTS ARE NOT NECESSARILY MORE STRESSFUL: the Vassos et al study suggested living in densely populated urban environments was a significant stress factor for schizophrenia. Romans- clarkson et al (1990) found no urban rural differences in mental health among women in New Zealand. Other studies Paykel et al (2000) found evidence of urban-rural differences, showed these differences disappeared after adjusting socio-economic differences for the two groups. This suggests that although social adversity may well be a significant trigger for the onset of schizophrenia, the claim that social adversity and urbanisation are synonymous is likely to be an over-simplification.
DIFFICULTIES IN DETERMINING CAUSAL STRESS: diathesis stress models make reference to stressful events that occur close to the onset of schizophrenia. However, it is possible that stressors earlier in life can also influence how people respond to later stressful events and increase their future susceptibility to the disorder. Hammen (1992) argues maladaptive methods of coping with stress in childhood and throughout development means that individuals fail to develop effective coping skills, which in turn comprises their resilience and increases vulnerability. Ineffective coping skills may therefore make life generally more stressful for the individual and so trigger mental illness.
LIMITATIONS OF THE TIERNARI ET AL STUDY: researchers in this study in deities a number of limitations of their study particularly in the assessment of adoptive family functioning. Psychiatric assessed stress in the adoptive family using the OPAS scale, they were assessing family functioning only at one given point in time. Tienari et al acknowledged that this fails to reflect developmental changes in family functioning over time. Observing reciprocal interactions between the adoptive family and the adoptees make it impossible to determine how much of the stress observed is assigned to the family and how much it actually caused by the adoptees themselves.
IMPLICATIONS FOR TREATMENT: if the onset of schizophrenia is a result of the additive effect of genetic vulnerability and environmental stress, then it has implications for the treatment of the disorder. Genetic vulnerability is difficult to control, certain other important factors interact with genetic vulnerability but this can be addressed with knowledge. Borglum et al (2014) found women infected with cytomegalovirus during pregnancy were more likely to have a child with schizophrenia, but only if both mother and child carried a particular gene defect. This suggests that the antiviral medicine during pregnancy may prevent the onset of schizophrenia in the offspring of women known to have this gene effect.
