Schizophrenia Research

Ø Beck et al (1962) reported a 52% concordance rate between experienced practitioners’ diagnoses when assessing 153 patients while Soderberg et al (2005) reported a concordance rate of 81% using the DSM classification system. This suggests that classification systems have become more reliable over time. Interestingly, Nilsson et al (2000) found only 60% concordance rate between practitioners using the ICD classification system, implying the DSM is more reliable. 

Ø Mason et al (1997) tested the ability of four different classification systems of diagnosis to predict the outcome of the disorder in 99 schizophrenic patients, finding more modern classification systems had high predictive validity, especially if only symptoms that lasted at least 6 months were considered. This suggests that predictive diagnosis has improved over time, as classification systems have been updated. 

Ø Goldman (1999) reported that 50% of schizophrenics had a co-morbid medical condition, such as substance abuse or polydipsia, making reliable and valid diagnosis of schizophrenia problematic. 

Ø Whaley (2004) believes the main reason for the incidence of schizophrenia among black Americans being greater then among white Americans is cultural bias, where ethnic differences in symptom expression are overlooked or misinterpreted by practitioners. This suggests a lack of validity in diagnosing cross-culturally.

Ø Lewin et al (1984) found that if clearer diagnostic criteria were applied, the number of female sufferers became much lower, suggesting a gender bias in original diagnosis. This was supported by Castle et al (1993), who found using more restrictive diagnostic criteria that the male incidence of the disorder was more than twice that of females. 

Ø Serper et al (1999) assessed patients with co-morbid schizophrenia and cocaine abuse, cocaine intoxication on its own and schizophrenia on its own. They found that although there was considerable symptom overlap in patients with schizophrenia and cocaine abuse, it was possible to make accurate diagnoses. 

Ø Gottesman & Shields (1976) reviewed five twin studies and reported a concordance rate of between 75% and 91% for MZ twins with severe forms of schizophrenia, suggesting that genetics plays a larger role with chronic forms of the disorder. Torrey et al (1994) reviewing evidence from twin studies, found that if one MZ twin develops schizophrenia, there is a 28% chance that the other twin will do so too, supporting the idea that schizophrenia is inherited. 

Ø Sorri et al (2004) performed a longitudinal study over 21 years on Finnish adoptees with biological mothers with schizophrenia, comparing them with adoptees whose biological mothers did not have schizophrenia, but also considered family rearing styles among adoptive families. Adoptees with a high genetic risk of developing schizophrenia were more sensitive to non-healthy rearing patterns, suggesting that environmental factors are important, too.

Ø Randrup &Munkvad (1966) created schizophrenic-like behaviour in rats by giving them amphetamines, which activate dopamine production, and then revered the effects by giving them neuroleptic drugs, which inhibit the release of dopamine, supporting the dopamine hypothesis. 

Ø Javitt (2007) reported that the drugs phencyclidine and ketamine induce schizophrenic symptoms in non-sufferers by blocking neurotransmission at NMDA-type glutamate receptors, which leads to abnormal dopamine system functioning in striatal and prefrontal brain areas, supporting the idea of a connection between dopamine and glutamate in the onset of schizophrenia. 

Ø Johnstone et al (1976) found that schizophrenics had enlarged ventricles, while non-sufferers did not, which suggests schizophrenia is related to a loss of brain tissue. Weyandt (2006) reported that enlarged ventricles are associated with negative symptoms only, which implies enlarged ventricles cannot explain all symptoms and incidences of schizophrenia. 

Ø Li et al (2010) performed a meta-analysis of fMRI studies investigating the difficulties schizophrenics often have in processing facial emotions, to find that although both schizophrenics and non-sufferers activate the bilateral amygdala and right fusiform gyri when processing facial emotions, the activation was severely limited in schizophrenics. This suggests that abnormal brain functioning in schizophrenics may explain their difficulties in processing facial emotions. 

Ø Tienari et al (2004) found that the level of schizophrenia in adopted individuals who were the biological children of schizophrenic mothers was 5.8% in those adopted by healthy families compared with 36.8% for children raised in dysfunctional families, which supports not only the family dysfunction theory but also the idea that individuals with high genetic vulnerability to schizophrenia are more affected by environmental stressors. 

Ø Kavanagh (1992) reviewed 26 studies of expressed emotion, finding that the mean relapse rate for schizophrenics who returned to live with high expressed emotion families was 48% compared with 21% for those who went to live with low expressed emotion families. This supports the idea that expressed emotion increases the risk of relapse for recovering schizophrenics. 

Ø Bowie & Harvey (2006) reviewed evidence to find that cognitive impairments are the core feature of schizophrenia mainly affecting attention, working memory, verbal learning and executive functions. These impairments pre-date the onset of the disorder and are found throughout the course of the illness. This supports Beck and Rector’s cognitive model.

Ø Betall et al (1991) found that schizophrenics struggled to identify words belonging to a certain category, such as birds, that they had read earlier, created themselves or had not seen before, supporting the idea that schizophrenics have meta-representation problems. 

Ø Davis et al (1989) performed a meta-analysis of more than 100 studies that compared antipsychotics with placebos, finding drugs to be more effective, with over 70% of sufferers treated with antipsychotics improving in condition after 6 weeks, while fewer than 25% improved with placebos, suggesting that antipsychotics have a beneficial medical effect.

Ø Schooler et al (2005), comparing the effectiveness of typical and atypical antipsychotics, found both effective in treating schizophrenia, with 75% of patients experiencing at least 20% reduction in symptoms. However, 55% of those receiving typical antipsychotics suffered relapses, compared with only 42% for typical treatment, with relapses occurring earlier in those taking typical drug treatments. Side effects were fewer with atypical antipsychotics. This implies that atypical drugs are superior. 

Ø McGorry et al (2002) found that after six months of treatment 36% of individuals with a high risk of first-onset schizophrenia who received supportive psychotherapy had developed schizophrenia, compared with only 10% who received drugs and CBT. This suggests CBT is more effective than psychotherapy in preventing first-onset schizophrenia. 

Ø Zimmerman et al (2005) performed a meta-analysis of 14 studies of CBT published between 1990 and 2004 involving 1484 patients, and found CBT significantly reduced positive symptoms and that the treatment was especially beneficial to those suffering a short-term acute schizophrenic episode. This implies that CBT is more appropriate when treating certain aspects of the disorder.  

Ø Leff et al (1985) compared family therapy with routine outpatient care for schizophrenics with families high in expressed emotion, finding in the first nine months of treatment 50% of those receiving routine care relapsed, compared with 8% of those receiving family therapy. This rose after two years to 75% relapsing who received routing care compared with 50% for the family therapy patients. This suggests family therapy is a comparatively effective theory, especially in the short term. 

Ø McFarlane et al (2003) reviewed available evidence to find that family therapy results in reduced relapse rates, symptom reduction in patients and improved relationships among family members, which leads to increased well-being for patients. This suggests that family therapy is an effective treatment, with an indication that better family relationships are the key element.

Ø McMonagle & Sultana (2000) conducted a meta-analysis of token economy programmes involving 110 schizophrenics, finding slight evidence for improved mental state, especially with negative symptoms. This gives a degree of support to the treatment. 

Ø Silverstein et al (2009) found that schizophrenics living in the community often have trouble performing jobs where they are paid on a long-term basis, such as monthly, as they have difficulty engaging in events to obtain distant rewards, but engage quite readily in situations using token economies where they are rewarded hourly or daily. This suggests that schizophrenics need to be paid more short-term basis when in employment. 

Ø Walker (1997) reported that schizophrenics have higher levels of cortisol than non-sufferers and that cortisol levels are related to severity of symptoms, with stress-related increases in cortisol levels heightening genetic-influenced abnormalities in dopamine transmission that underpins vulnerability to schizophrenia, triggering the onset of the disorder. This illustrates the interaction of biological and environmental factors in the development of schizophrenia in line with the diathesis-stress model. 

Ø Cannon et al (2002) reviewed available evidence, to find a positive correlation between birth complications and a later vulnerability to developing schizophrenia, with some indication of damage to hormone and neurotransmitter systems, as well as the immune system. This again supports an interactionist explanation of schizophrenia, where biological vulnerabilities interact with later stressors to trigger the disorder. 

Ø Guo et al (2010) reported that patients in the early stages of schizophrenia who receive a combination of antipsychotics and a psychological therapy have improved insight, quality of life and social functioning and are therefore less likely to discontinue treatment or relapse than those taking antipsychotics alone, illustrating the value of a combined treatment. 

Ø Sudak (2011) reports that antipsychotic drug medication combined with CBT strengthens adherence to drug treatment, as the CBT gives the patient rational insight into the benefits of adhering to their drug treatment, increasing their chances of improvement. This again illustrates a benefit of combining treatments