A polydiagnostic approach to the differences in the symptoms of schizophrenia in different cultural and ethnic populations

Schizophrenia: the new etiological synthesis

Schizophrenia has been an evolutionary paradox: it has high heritability, but it is associated with decreased reproductive success. The causal genetic variants underlying schizophrenia are thought to be under weak negative selection. To unravel this paradox, many evolutionary explanations have been suggested for schizophrenia. We critically discuss the constellation of evolutionary hypotheses for schizophrenia, highlighting the lack of empirical support for most existing evolutionary hypotheses-with the exception of the relatively well supported evolutionary mismatch hypothesis. It posits that evolutionarily novel features of contemporary environments, such as chronic stress, low-grade systemic inflammation, and gut dysbiosis, increase susceptibility to schizophrenia. Environmental factors such as microbial infections (e.g., Toxoplasma gondii) can better predict the onset of schizophrenia than polygenic risk scores. However, researchers have not been able to explain why only a small minority of infected people develop schizophrenia. The new etiological synthesis of schizophrenia indicates that an interaction between host genotype, microbe infection, and chronic stress causes schizophrenia, with neuroinflammation and gut dysbiosis mediating this etiological pathway. Instead of just alleviating symptoms with drugs, the parasite x genotype x stress model emphasizes that schizophrenia treatment should focus on detecting and treating possible underlying microbial infection(s), neuroinflammation, gut dysbiosis, and chronic stress.

Cross-country variations in the reporting of psychotic symptoms among sub-Saharan African adults: A psychometric evaluation of the Psychosis Screening Questionnaire

BACKGROUND

Self-reporting of psychotic symptoms varies significantly between cultures and ethnic groups. Yet, limited validated screening instruments are available to capture such differences in the African continent.

METHODOLOGY

Among 9,059 individuals participating as controls in a multi-country case-control study of the genetic causes of psychosis, we evaluated the psychometric properties of the Psychosis Screening Questionnaire (PSQ). We applied multi-group confirmatory factor analysis and item response theory to assess item parameters.

RESULTS

The overall positive endorsement of at least one item assessing psychotic symptoms on the PSQ was 9.7%, with variability among countries (Uganda 13.7%, South Africa 11%, Kenya 10.2%, and Ethiopia 2.8%). A unidimensional model demonstrated good fit for the PSQ (root mean square error of approximation = 0.009; comparative fit index = 0.997; and Tucker-Lewis Index = 0.995). Hypomania had the weakest association with single latent factor (standardized factor loading 0.62). Sequential multi-group confirmatory factor analysis demonstrated that PSQ items were measured in equivalent ways across the four countries. PSQ items gave more information at higher levels of psychosis, with hypomania giving the least discriminating information.

LIMITATIONS

Participants were recruited from general medical facilities, so findings may not be generalizable to the general population.

CONCLUSION

The PSQ demonstrated a unidimensional factor structure in these samples. Items were measured equivalently across all study settings, suggesting that differences in prevalence of psychotic symptoms between countries were less likely to represent measurement artifact. The PSQ is more reliable in screening for psychosis in individuals with higher degrees of psychotic experiences-hypomania excluded-and might decrease the false-positive rate from mild nonspecific psychotic experiences.

Investigating ethnic variations in reporting of psychotic symptoms: a multiple-group confirmatory factor analysis of the Psychosis Screening Questionnaire

BACKGROUND

Epidemiological evidence suggests risk for psychosis varies with ethnicity in Western countries. However, there is little evidence to date on the cross-cultural validity of screening instruments used for such comparisons.

METHODS

Combining two existing UK population-based cohorts, we examined risk for reporting psychotic symptoms across White British (n = 3467), White Irish (n = 851), Caribbean (n = 1899), Indian (n = 2590), Pakistani (n = 1956) and Bangladeshi groups (n = 1248). We assessed the psychometric properties of the Psychosis Screening Questionnaire (PSQ) with a multiple-group confirmatory factor analysis, assessing the equivalence of factor loadings, response thresholds and residual variances in an analysis of measurement non-invariance.

RESULTS

Compared with prevalence among British Whites (5.4%), the prevalence of self-reported psychotic symptoms was greater in the Caribbean group (12.7%, adjusted OR = 2.38 [95% CI 1.84-3.07]). Prevalence was also increased among Pakistani individuals (8.3%, adjusted OR = 1.36 [1.01-1.84]) although this difference was driven by a greater likelihood of reporting paranoid symptoms. PSQ items for thought interference, strange experience and hallucination were measured in equivalent ways across ethnic groups. However, our measurement models suggested that paranoid symptoms were measured less reliably among ethnic minorities than among British Whites and appeared to exaggerate latent differences between Pakistani and White British groups when measurement non-invariance was not accounted for.

CONCLUSIONS

Notwithstanding evidence for measurement non-invariance, the greater risk for reporting psychotic symptoms among Caribbean individuals is unlikely to be an artefact of measurement. Greater residual variance in the recording of paranoid symptoms among ethnic minority respondents warrants caution in using this item to investigate ethnic variation in psychosis risk.

Symptom profiles and explanatory models of first-episode psychosis in African-, Caribbean- and European-origin groups in Ontario

AIM

To assess variability in symptom presentation and explanatory models of psychosis for people from different ethnic groups.

METHODS

Clients with first-episode psychosis (n = 171) who identified as black African, black Caribbean or white European were recruited from early intervention programmes in Toronto and Hamilton. We compared results by ethnic group for symptom profiles and explanatory models of illness.

RESULTS

Clients of black Caribbean origin had a lower odds of reporting that they were speaking incomprehensibly (OR = 0.36; 95% CI: 0.14-0.90) and black African clients had a greater odds of reporting persistent aches or pains (OR = 2.92; 95% CI: 1.32-6.50). Black African clients had a lower odds of attributing the cause of psychosis to hereditary factors (OR = 0.41; 95% CI: 0.19-0.89) or to substance abuse (OR = 0.29; 95% CI: 0.13-0.67) and had a lower odds of assigning responsibility for their illness to themselves (OR = 0.41; 95% CI: 0.19-0.89).

CONCLUSIONS

Understanding the differences in illness models for ethnic minority groups may help improve the cultural competence of mental health services.

The content of delusions in a sample of South African Xhosa people with schizophrenia

BACKGROUND

Although the relationship between cultural beliefs and schizophrenia has received some attention, relatively little work has emerged from African contexts. In this study we draw from a sample of South African Xhosa people with schizophrenia, exploring their cultural beliefs and explanations of illness. The purpose of the article is to examine the relationship between this cultural context and the content of delusions.

METHODS

A sample comprising 200 Xhosa people with schizophrenia participating in a South African schizophrenia genomics study were interviewed using the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I). Participant delusions were thematically analyzed for recurring themes.

RESULTS

The majority of participants (n = 125 72.5%) believed that others had bewitched them in order to bring about their mental illness, because they were in some way jealous of the participant. This explanation aligns well with the understanding of jealousy-induced witchcraft in Southern African communities and highlights the important role that culture plays in their content of delusions.

CONCLUSIONS

Improved knowledge of these explanatory frameworks highlights the potential value of culturally sensitive assessment tools and stigma interventions in patient recovery. Furthermore such qualitative analyses contribute towards discussion about aspects of delusional thought that may be more universally stable, and those that may be more culturally variable.

Evolutionary Considerations on the Emerging Subculture of the E-psychonauts and the Novel Psychoactive Substances: A Comeback to the Shamanism?

BACKGROUND

Evolutionary research on drug abuse has hitherto been restricted to proximate studies, considering aetiology, mechanism, and ontogeny. However, in order to explain the recent emergency of a new behavioral pattern (e.g. 'the e-psychonaut style') of novel psychoactive substances' (NPS) intake, a complementary evolutionary model may be needed.

OBJECTIVE

A range of evolutionary interpretations on the 'psychonaut style' and the recent emergency of NPS were here considered.

METHOD

The PubMed database was searched in order to elicit evolutionary theory-based documents commenting on NPS/NPS users/e-psychonauts.

RESULTS

The traditional 'shamanic style' use of entheogens/plant-derived compounds may present with a range of similarities with the 'e-psychonauts' use of mostly of hallucinogen/psychedelic NPS. These users consider themselves as 'new/technological' shamans.

CONCLUSION

Indeed, a range of evolutionary mechanisms, such as: optimal foraging, costly signaling, and reproduction at the expense of health may all cooperate to explain the recent spread and diffusion of the NPS market, and this may represent a reason of concern.

Validation of a modified version of the PRIME screen for psychosis-risk symptoms in a non-clinical Kenyan youth sample

BACKGROUND

The PRIME screen is a self-administered questionnaire designed to quickly assess individuals at risk for developing a psychotic disorder. It is shorter in both length and administration time compared to the Structured Interview for Psychosis-Risk Syndromes (SIPS)-a standard instrument for psychosis prodromal risk assessment. Validation of the PRIME against the SIPS has not been reported in large non-clinical populations.

METHODS

A culturally modified version of the PRIME screen (mPRIME) was administered to Kenyan youth between the ages of 14 and 29. 182 completed both the SIPS and mPRIME. Validation measures (sensitivity, specificity, positive predictive value, negative predictive value) were calculated and the study sample was then broken down into true positives, false positives, and false negatives for comparison on different quantitative measures.

RESULTS

Using previously suggested thresholds for a positive screen, the mPRIME had a sensitivity of 40% and a specificity of 64.8% for our entire sample. Positive predictive value (PPV) and negative predictive value (NPV) were 12.3% and 89.7%, respectively. Breaking the sample down by questionnaire outcome showed that true-positive individuals scored higher on average rate and intensity of endorsement of mPRIME items compared to false-positive and false-negatives, while false-negatives on average registered disagreement on all mPRIME questionnaire items.

CONCLUSIONS

The mPRIME does not appear to be an effective screener of at-risk individuals for psychosis in our non-clinical sample. Further validation efforts in other general populations are warranted.

Knowledge of psychiatric terms and concepts among Kenyan youth: analysis of focus group discussions

Psychiatric disorders and symptoms are common worldwide. However, cultural differences in symptom manifestation and knowledge of psychiatric terms and concepts represent a challenge to accurate clinical assessment. Our previous youth surveys revealed higher rates of psychotic experiences in Kenya compared to several other countries, suggesting culture may influence psychosis risk assessment survey results. The goal of the present investigation is to evaluate understanding of general mental health related terms and concepts and specific items from the Structured Interview for Psychosis-Risk Symptoms (SIPS), a commonly used psychosis risk assessment instrument. Six focus groups were conducted in Nairobi, Kenya and surrounding areas with young adults from the community, university and secondary school students, and mental health professionals. Analysis of the information obtained from participants indicated that adolescents and young adults in Kenya were aware of mental illness in their communities, but had very limited knowledge of the meaning of specific psychiatric disorders and symptoms. Many believed that the cause of mental illness was spiritual in nature. These results suggest that in order to obtain accurate reported rates of psychiatric symptoms, assessment of Kenyan adolescents and young adults requires elaboration of assessment questions and use of simplified terms.

The evolutionary paradox and the missing heritability of schizophrenia

Schizophrenia is one of the most detrimental common psychiatric disorders, occurring at a prevalence of approximately 1%, and characterized by increased mortality and reduced reproduction, especially in men. The heritability has been estimated around 70% and the genome-wide association meta-analyses conducted by the Psychiatric Genomics Consortium have been successful at identifying an increasing number of risk loci. Various theories have been proposed to explain why genetic variants that predispose to schizophrenia persist in the population, despite the fitness reduction in affected individuals, a question known as the evolutionary paradox. In this review, we consider evolutionary perspectives of schizophrenia and of the empirical evidence that may support these perspectives. Proposed evolutionary explanations include balancing selection, fitness trade-offs, fluctuating environments, sexual selection, mutation-selection balance and genomic conflicts. We address the expectations about the genetic architecture of schizophrenia that are predicted by different evolutionary scenarios and discuss the implications for genetic studies. Several potential sources of "missing" heritability, including gene-environment interactions, epigenetic variation, and rare genetic variation are examined from an evolutionary perspective. A better understanding of evolutionary history may provide valuable clues to the genetic architecture of schizophrenia and other psychiatric disorders, which is highly relevant to genetic studies that aim to detect genetic risk variants.

A survey of psychosis risk symptoms in Kenya

Defining the prepsychotic state in an effort to prevent illness progression and the development of disorders such as schizophrenia is a rapidly growing area of psychiatry. The presentation of psychotic symptoms can be influenced by culture; however, there has not been any previous assessment of psychosis risk symptoms in the continent of Africa. Our study aimed to measure the prevalence of psychosis risk in a community sample in Nairobi, Kenya, and to evaluate the effects of key demographic variables. A culturally modified version of the 12-item PRIME-Screen (mPRIME) was self-administered by 2758 youth (aged 14-29 years) recruited through house-to-house visits in Nairobi, Kenya. The prevalence and severity of psychosis risk items from the mPRIME and the effects of sex and age on symptoms were evaluated. k-Means cluster analysis was used to identify symptom groups. Depending on the mPRIME item, 1.8% to 19.5% of participants reported certainty of having had a psychosis risk symptom. Overall, 45.5% reported having had any psychosis risk symptom. Females had a significantly higher mean severity score on items evaluating persecutory ideation and auditory hallucinations. Symptom severity on 5 items showed a modest (R = 0.09-0.13) but significant correlation with age. Cluster analysis identified 4 groups of participants: normative (55%), high symptom (11%), intermediate symptom (19%), and grandiose symptom (15%). Psychosis risk symptoms appear to be highly prevalent in Kenyan youth. Longitudinal studies are needed to determine the correlation of identified symptoms with transition to psychotic illness, as well as the associated functionality and distress, to develop appropriate intervention strategies.

Prevalence and characteristics of psychotic-like experiences in Kenyan youth

Current evidence suggests that there may be significant differences in psychotic symptom prevalence in Africa compared with other cultures. However, there have been few studies evaluating these symptoms in the continent. We conducted a cross-sectional survey of psychotic-like experiences (PLEs) in 2963 Kenyan students from seven tertiary academic institutions spread across Kenya, using a self-administered psychosis questionnaire evaluating psychotic experiences and demographic variables. Logistic regression was used to evaluate relationship between PLEs and demographic variables. Latent class analysis (LCA) was used to determine specific classes of psychotic experiences. Twenty-three percent of respondents reported having at least one PLE, and 19% reported this unrelated to drug use or sleep. Compared to students identifying as Protestant Christians, Catholics had a lower likelihood of having any PLE or visual hallucinations. Other demographic variables were not significantly associated with PLEs. LCA of PLEs resulted in a three-class model that comprised 1) a non-psychotic class (83.8%), 2) a predominantly hallucinatory class ("type I PLE"; 12.7%), and 3) a multiple symptom class ("type II PLE"; 3.5%). Both psychotic classes had a predominance of male students. Further studies are required to clarify functionality and clinical progression associated with observed patterns of psychosis, as well as the generalizability of our findings.

Religion and psychosis: a common evolutionary trajectory?

In this article we propose that schizophrenia and religious cognition engage cognate mental modules in the over-attribution of agency and the overextension of theory of mind. We argue similarities and differences between assumptions of ultrahuman agents with omniscient minds and certain ''pathological'' forms of thinking in schizophrenia: thought insertion, withdrawal and broadcasting, and delusions of reference. In everyday religious cognition agency detection and theory of mind modules function ''normally,'' whereas in schizophrenia both modules are impaired. It is suggested that religion and schizophrenia have perhaps had a related evolutionary trajectory.

Competing definitions of schizophrenia: what can be learned from polydiagnostic studies?

The contemporary diagnoses of schizophrenia (sz)-Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition(DSM-IV) and International Classification of Diseases, 10th Revision(ICD-10)-are widely considered as important scientific achievements. However, these algorithms were not a product of explicit conceptual analyses and empirical studies but defined through consensus with the purpose of improving reliability. The validity status of current definitions and of their predecessors remains unclear. The so-called "polydiagnostic approach" applies different definitions of a disorder to the same patient sample in order to compare these definitions on potential validity indicators. We reviewed 92 polydiagnostic sz studies published since the early 1970s. Different sz definitions show a considerable variation concerning frequency, concordance, reliability, outcome, and other validity measures. The DSM-IV and the ICD-10 show moderate reliability but both definitions appear weak in terms of concurrent validity, eg, with respect to an aggregation of a priori important features. The first-rank symptoms of Schneider are not associated with family history of sz or with prediction of poor outcome. The introduction of long duration criteria and exclusion of affective syndromes tend to restrict the diagnosis to chronic stable patients. Patients fulfilling the majority of definitions (core sz patients) do not seem to constitute a strongly valid subgroup but rather a severely ill subgroup. Paradoxically, it seems that a century after the introduction of the sz concept, research is still badly needed, concerning conceptual and construct validity of sz, its essential psychopathological features, and phenotypic boundaries.

Cross-ethnic evaluation of psychotic symptom content in hospitalized middle-aged and older adults

OBJECTIVE

The objective of this study was to examine ethnic differences in the content of delusions and hallucinations among a tri-ethnic sample of adult psychiatric inpatients older than 40 years who were hospitalized with an acute psychotic episode.

METHODS

A chart review of inpatient episodes for 133 middle-aged and older adult patients (31 African Americans, 50 Latinos, and 52 Euro-Americans) with a mean age of 50 years was performed at an acute behavioral medicine unit at a university hospital. All patients were diagnosed with a severe psychotic disorder. The content and frequency of psychotic symptoms were systematically reviewed using a structured checklist and comparisons across ethnic groups were made using chi(2) statistics.

RESULTS

Ethnic group differences were found in the contents and subtypes of delusions and hallucinations. Significant ethnic differences were found in symptom content, consistent with findings from studies on younger samples of inpatients. Euro-Americans were nearly twice as likely as Latinos to report delusions of grandiosity. African Americans were more likely than Latinos to report general paranoid delusions of persecution. Latinos reported more culturally influenced contents than the other groups.

CONCLUSION

Raising provider awareness of ethnic variation in symptom expression is a key step in the process of developing effective treatments for ethnically diverse middle-aged and older patient populations.

Evolutionary perspectives on schizophrenia

The theory of evolution may be relevant to psychiatric disorders. Evolution reflects changes in genes throughout time. Thus, evolutionary forces can shape any phenotype that is genetically rooted and that possesses a long history. Schizophrenia is likely an ancient condition with a substantial genetic component. Since the 1960s, several researchers have applied evolutionary principles to the study of schizophrenia. In general, schizophrenia is either viewed as an evolutionary advantageous condition or as a disadvantageous byproduct of normal brain evolution. This paper reviews major evolutionary explanations--historical and current--that speculate on the possible origins of schizophrenia.

How shamanism and group selection may reveal the origins of schizophrenia

Schizophrenia, with its apparent genetic basis, persists despite demonstrating impaired fecundity. Although this has been considered paradoxical, a similar paradigm is observed elsewhere in nature. Honey bee colonies possess sterile task specialists whose presence can best be understood by the evolutionary principle of group selection. Group selection may be pertinent to human history and consequently schizophrenia could represent an ancient form of behavioral specialization. Shamanism and religion demonstrate some similarities to psychosis and may provide clues regarding the origins of schizophrenia.