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Mitteroecker P, Merola GP. The cliff edge model of the evolution of schizophrenia: Mathematical, epidemiological, and genetic evidence. Neurosci Biobehav Rev 2024; 160:105636. [PMID: 38522813 DOI: 10.1016/j.neubiorev.2024.105636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 02/27/2024] [Accepted: 03/16/2024] [Indexed: 03/26/2024]
Abstract
How has schizophrenia, a condition that significantly reduces an individual's evolutionary fitness, remained common across generations and cultures? Numerous theories about the evolution of schizophrenia have been proposed, most of which are not consistent with modern epidemiological and genetic evidence. Here, we briefly review this evidence and explore the cliff edge model of schizophrenia. It suggests that schizophrenia is the extreme manifestation of a polygenic trait or a combination of traits that, within a normal range of variation, confer cognitive, linguistic, and/or social advantages. Only beyond a certain threshold, these traits precipitate the onset of schizophrenia and reduce fitness. We provide the first mathematical model of this qualitative concept and show that it requires only very weak positive selection of the underlying trait(s) to explain today's schizophrenia prevalence. This prediction, along with expectations about the effect size of schizophrenia risk alleles, are surprisingly well matched by empirical evidence. The cliff edge model predicts a dynamic change of selection of risk alleles, which explains the contradictory findings of evolutionary genetic studies.
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Affiliation(s)
- Philipp Mitteroecker
- Unit for Theoretical Biology, Department of Evolutionary Biology, University of Vienna, Djerassiplatz 1, Vienna, Austria; Konrad Lorenz Institute for Evolution and Cognition Research, Martinstrasse 12, Klosterneuburg, Vienna, Austria.
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2
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Guardiola-Ripoll M, Almodóvar-Payá C, Arias-Magnasco A, Latorre-Guardia M, Papiol S, Canales-Rodríguez EJ, García-León MÁ, Fuentes-Claramonte P, Salavert J, Tristany J, Torres L, Rodríguez-Cano E, Salvador R, Pomarol-Clotet E, Fatjó-Vilas M. Human-specific evolutionary markers linked to foetal neurodevelopment modulate brain surface area in schizophrenia. Commun Biol 2023; 6:1040. [PMID: 37833414 PMCID: PMC10576001 DOI: 10.1038/s42003-023-05356-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 09/13/2023] [Indexed: 10/15/2023] Open
Abstract
Schizophrenia may represent a trade-off in the evolution of human-specific ontogenetic mechanisms that guide neurodevelopment. Human Accelerated Regions (HARs) are evolutionary markers functioning as neurodevelopmental transcription enhancers that have been associated with brain configuration, neural information processing, and schizophrenia risk. Here, we have investigated the influence of HARs' polygenic load on neuroanatomical measures through a case-control approach (128 patients with schizophrenia and 115 controls). To this end, we have calculated the global schizophrenia Polygenic Risk Score (Global PRSSZ) and that specific to HARs (HARs PRSSZ). We have also estimated the polygenic burden restricted to the HARs linked to transcriptional regulatory elements active in the foetal brain (FB-HARs PRSSZ) and the adult brain (AB-HARs PRSSZ). We have explored the main effects of the PRSs and the PRSs x diagnosis interactions on brain regional cortical thickness (CT) and surface area (SA). The results indicate that a higher FB-HARs PRSSZ is associated with patients' lower SA in the lateral orbitofrontal cortex, the superior temporal cortex, the pars triangularis and the paracentral lobule. While noHARs-derived PRSs show an effect on the risk, our neuroanatomical findings suggest that the human-specific transcriptional regulation during the prenatal period underlies SA variability, highlighting the role of these evolutionary markers in the schizophrenia genomic architecture.
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Affiliation(s)
- Maria Guardiola-Ripoll
- FIDMAG Germanes Hospitalàries Research Foundation, Barcelona, Spain.
- CIBERSAM (Biomedical Research Network in Mental Health; Instituto de Salud Carlos III), Madrid, Spain.
| | - Carmen Almodóvar-Payá
- FIDMAG Germanes Hospitalàries Research Foundation, Barcelona, Spain
- CIBERSAM (Biomedical Research Network in Mental Health; Instituto de Salud Carlos III), Madrid, Spain
| | | | | | - Sergi Papiol
- CIBERSAM (Biomedical Research Network in Mental Health; Instituto de Salud Carlos III), Madrid, Spain
- Institute of Psychiatric Phenomics and Genomics (IPPG), University Hospital, LMU Munich, Munich, Germany
- Max Planck Institute of Psychiatry, Munich, Germany
| | - Erick J Canales-Rodríguez
- CIBERSAM (Biomedical Research Network in Mental Health; Instituto de Salud Carlos III), Madrid, Spain
- Signal Processing Laboratory 5 (LTS5), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - María Ángeles García-León
- FIDMAG Germanes Hospitalàries Research Foundation, Barcelona, Spain
- CIBERSAM (Biomedical Research Network in Mental Health; Instituto de Salud Carlos III), Madrid, Spain
| | - Paola Fuentes-Claramonte
- FIDMAG Germanes Hospitalàries Research Foundation, Barcelona, Spain
- CIBERSAM (Biomedical Research Network in Mental Health; Instituto de Salud Carlos III), Madrid, Spain
| | - Josep Salavert
- Hospital Sant Rafael, Germanes Hospitalàries, Barcelona, Spain
| | - Josep Tristany
- Hospital Sagrat Cor, Germanes Hospitalàries, Martorell, Spain
| | - Llanos Torres
- Hospital Mare de Déu de la Mercè, Germanes Hospitalàries, Barcelona, Spain
| | - Elena Rodríguez-Cano
- FIDMAG Germanes Hospitalàries Research Foundation, Barcelona, Spain
- CIBERSAM (Biomedical Research Network in Mental Health; Instituto de Salud Carlos III), Madrid, Spain
- Hospital Benito Menni, Germanes Hospitalàries, Sant Boi de Llobregat, Spain
| | - Raymond Salvador
- FIDMAG Germanes Hospitalàries Research Foundation, Barcelona, Spain
- CIBERSAM (Biomedical Research Network in Mental Health; Instituto de Salud Carlos III), Madrid, Spain
| | - Edith Pomarol-Clotet
- FIDMAG Germanes Hospitalàries Research Foundation, Barcelona, Spain
- CIBERSAM (Biomedical Research Network in Mental Health; Instituto de Salud Carlos III), Madrid, Spain
| | - Mar Fatjó-Vilas
- FIDMAG Germanes Hospitalàries Research Foundation, Barcelona, Spain.
- CIBERSAM (Biomedical Research Network in Mental Health; Instituto de Salud Carlos III), Madrid, Spain.
- Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals, Universitat de Barcelona, Barcelona, Spain.
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Applying Principles from Medicine Back to Artificial Intelligence. Artif Intell Med 2022. [DOI: 10.1007/978-3-030-64573-1_289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Gualtieri CT. Genomic Variation, Evolvability, and the Paradox of Mental Illness. Front Psychiatry 2021; 11:593233. [PMID: 33551865 PMCID: PMC7859268 DOI: 10.3389/fpsyt.2020.593233] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 11/27/2020] [Indexed: 12/30/2022] Open
Abstract
Twentieth-century genetics was hard put to explain the irregular behavior of neuropsychiatric disorders. Autism and schizophrenia defy a principle of natural selection; they are highly heritable but associated with low reproductive success. Nevertheless, they persist. The genetic origins of such conditions are confounded by the problem of variable expression, that is, when a given genetic aberration can lead to any one of several distinct disorders. Also, autism and schizophrenia occur on a spectrum of severity, from mild and subclinical cases to the overt and disabling. Such irregularities reflect the problem of missing heritability; although hundreds of genes may be associated with autism or schizophrenia, together they account for only a small proportion of cases. Techniques for higher resolution, genomewide analysis have begun to illuminate the irregular and unpredictable behavior of the human genome. Thus, the origins of neuropsychiatric disorders in particular and complex disease in general have been illuminated. The human genome is characterized by a high degree of structural and behavioral variability: DNA content variation, epistasis, stochasticity in gene expression, and epigenetic changes. These elements have grown more complex as evolution scaled the phylogenetic tree. They are especially pertinent to brain development and function. Genomic variability is a window on the origins of complex disease, neuropsychiatric disorders, and neurodevelopmental disorders in particular. Genomic variability, as it happens, is also the fuel of evolvability. The genomic events that presided over the evolution of the primate and hominid lineages are over-represented in patients with autism and schizophrenia, as well as intellectual disability and epilepsy. That the special qualities of the human genome that drove evolution might, in some way, contribute to neuropsychiatric disorders is a matter of no little interest.
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Applying Principles from Medicine Back to Artificial Intelligence. Artif Intell Med 2021. [DOI: 10.1007/978-3-030-58080-3_289-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Carr P. The value of visioning: Augmenting EMDR with alpha-band alternating bilateral photic stimulation for trauma treatment in schizophrenia. Med Hypotheses 2020; 144:110184. [DOI: 10.1016/j.mehy.2020.110184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 07/27/2020] [Accepted: 08/13/2020] [Indexed: 11/28/2022]
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Takamatsu Y, Ho G, Waragai M, Wada R, Sugama S, Takenouchi T, Masliah E, Hashimoto M. Transgenerational Interaction of Alzheimer's Disease with Schizophrenia through Amyloid Evolvability. J Alzheimers Dis 2020; 68:473-481. [PMID: 30741673 PMCID: PMC6484278 DOI: 10.3233/jad-180986] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Alzheimer's disease (AD), the most common neurodegenerative dementia, leads to memory dysfunction due to widespread neuronal loss associated with aggregation of amyloidogenic proteins (APs), while schizophrenia (SCZ) represents a major psychiatric disorder characterized by delusions, hallucinations, and other cognitive abnormalities, the underlying mechanisms of which remain obscure. Although AD and SCZ partially overlap in terms of psychiatric symptoms and some aspects of cognitive impairment, the causal relationship between AD and SCZ is unclear. Based on the similarity of APs with yeast prion in terms of stress-induced protein aggregation, we recently proposed that evolvability of APs might be an epigenetic phenomenon to transmit stress information of parental brain to cope with the stressors in offspring. Although amyloid evolvability may be beneficial in evolution, AD might be manifested during parental aging as the mechanism of antagonistic pleiotropy phenomenon. Provided that accumulating evidence implicates stress as an important factor in SCZ, the main objective of this paper is to better understand the possible connection of AD and SCZ through amyloid evolvability. Hypothetically, the delivery of information of stress by APs may be less efficient under the decreased evolvability conditions such as disease-modifying treatment, leading to SCZ in offspring. Conversely, the increased evolvability conditions including gene mutations of APs are supposed to be beneficial for offspring, but might lead to AD in parents. Collectively, AD and SCZ might transgenerationally interfere with each other through amyloid evolvability, and this could explain why both AD and SCZ have not been selected out through evolution.
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Affiliation(s)
- Yoshiki Takamatsu
- Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo, Japan
| | - Gilbert Ho
- PCND Neuroscience Research Institute, Poway, CA, USA
| | - Masaaki Waragai
- Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo, Japan
| | - Ryoko Wada
- Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo, Japan
| | - Shuei Sugama
- Department of Physiology, Nippon Medical School, Tokyo, Japan
| | - Takato Takenouchi
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, Tsukuba, Ibaraki, Japan
| | - Eliezer Masliah
- Division of Neurosciences, National Institute on Aging, National Institutes of Health, Bethesda, MD, USA
| | - Makoto Hashimoto
- Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo, Japan
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Yao Y, Yang J, Xie Y, Liao H, Yang B, Xu Q, Rao S. No Evidence for Widespread Positive Selection Signatures in Common Risk Alleles Associated with Schizophrenia. Schizophr Bull 2020; 46:603-611. [PMID: 31150552 PMCID: PMC7147583 DOI: 10.1093/schbul/sbz048] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Schizophrenia poses an evolutionary-genetic paradox as it exhibits strongly negative fitness effects (early mortality and decreased fecundity), yet it persists at a prevalence of approximately 1% worldwide. Evidence from several studies have suggested that schizophrenia is evolved and maintained in part as a maladaptive byproduct of recent positive selection and adaptive evolution in human beings. However, inconsistent results have been also proposed, challenging the recent positive selection theory to explain the high population frequency of schizophrenia-associated alleles. Here, we used public domain data to locate signatures of positive selection based on genetic diversity, derived allele frequency, differentiation between populations, and long haplotypes at schizophrenia-associated single nucleotide polymorphisms (SNPs) and randomly selected SNPs (as negative controls). We found evidence for positive selection at 10 out of the 105 schizophrenia-associated SNPs, while 5 of these SNPs involved positive selection for the protective allele. Taken together, the absence of widespread positive selection signals at the schizophrenia-associated SNPs, along with the fact that half of the positive selection favored the protective allele, provide little evidence supporting the positive selection theory in schizophrenia.
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Affiliation(s)
- Yao Yao
- State Key Laboratory of Biotherapy and Collaborative Innovation Center for Biotherapy, West China Second University Hospital, Sichuan University, Chengdu, China,School of Life Science and Engineering, Southwest Jiaotong University, Chengdu, China,School of Basic Medicine, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Jia Yang
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Yimin Xie
- School of Basic Medicine, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Hai Liao
- School of Life Science and Engineering, Southwest Jiaotong University, Chengdu, China
| | - Baoying Yang
- College of Mathematics, Southwest Jiaotong University, Chengdu, China
| | - Qi Xu
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Shuquan Rao
- School of Life Science and Engineering, Southwest Jiaotong University, Chengdu, China,State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China,To whom correspondence should be addressed; tel: +86 28 87603202; fax: +86 28 87603202; e-mail:
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Cariaga-Martinez A, Gutiérrez K, Alelú-Paz R. Rethinking schizophrenia through the lens of evolution: shedding light on the enigma. RESEARCH IDEAS AND OUTCOMES 2018. [DOI: 10.3897/rio.4.e28459] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Schizophrenia refers to a complex psychiatric illness characterized by the heterogenic presence of positive, negative and cognitive symptoms occurring in all human societies. The fact that the disorder lacks a unifying neuropathology, presents a decreased fecundity of the affected individuals and has a cross-culturally stable incidence rate, makes it necessary for an evolutionary explanation that fully accounts for the preservation of “schizophrenic genes” in the global human genepool, explaining the potential sex differences and the heterogeneous cognitive symptomatology of the disorder and is consistent with the neuropsychological, developmental and evolutionary findings regarding the human brain. Here we proposed a new evolutionary framework for schizophrenia that is consistent with findings presented in different dimensions, considering the disorder as a form of brain functioning that allows us to adapt to the environment and, ultimately, maintain the survival of the species. We focus on the epigenetic regulation of thalamic interneurons as a major player involved in the development of the clinical picture characteristic of schizophrenia.
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11
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Genetic predilections and predispositions for the development of shamanism. Behav Brain Sci 2018; 41:e73. [DOI: 10.1017/s0140525x17002047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractSingh's cultural evolutionary theory of shamanism provides a valuable framework for understanding shamanism. We argue, however, that a full understanding of shamanism should incorporate the psychological predilections and genetic predispositions commonly found in individual shamans. In other words, only a small subset of individuals in a culture is prone or attracted to shamanistic practices, regardless of the evolutionary value of those practices.
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12
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Viscardi LH, Paixão-Côrtes VR, Comas D, Salzano FM, Rovaris D, Bau CD, Amorim CEG, Bortolini MC. Searching for ancient balanced polymorphisms shared between Neanderthals and Modern Humans. Genet Mol Biol 2018; 41:67-81. [PMID: 29658973 PMCID: PMC5901502 DOI: 10.1590/1678-4685-gmb-2017-0308] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 11/26/2017] [Indexed: 01/06/2023] Open
Abstract
Hominin evolution is characterized by adaptive solutions often rooted in behavioral and cognitive changes. If balancing selection had an important and long-lasting impact on the evolution of these traits, it can be hypothesized that genes associated with them should carry an excess of shared polymorphisms (trans- SNPs) across recent Homo species. In this study, we investigate the role of balancing selection in human evolution using available exomes from modern (Homo sapiens) and archaic humans (H. neanderthalensis and Denisovan) for an excess of trans-SNP in two gene sets: one associated with the immune system (IMMS) and another one with behavioral system (BEHS). We identified a significant excess of trans-SNPs in IMMS (N=547), of which six of these located within genes previously associated with schizophrenia. No excess of trans-SNPs was found in BEHS, but five genes in this system harbor potential signals for balancing selection and are associated with psychiatric or neurodevelopmental disorders. Our approach evidenced recent Homo trans-SNPs that have been previously implicated in psychiatric diseases such as schizophrenia, suggesting that a genetic repertoire common to the immune and behavioral systems could have been maintained by balancing selection starting before the split between archaic and modern humans.
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Affiliation(s)
- Lucas Henriques Viscardi
- Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | | | - David Comas
- Institut de Biologia Evolutiva (CSIC-UPF), Departament de Ciències Experimentals i de LaSalut, Universitat Pompeu Fabra, Barcelona, Spain
| | - Francisco Mauro Salzano
- Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Diego Rovaris
- Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Claiton Dotto Bau
- Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Carlos Eduardo G. Amorim
- Department of Biological Sciences, Columbia University, New York, NY, U.S.A
- Department of Ecology and Evolution, Stony Brook University, Stony Brook, NY, U.S.A
| | - Maria Cátira Bortolini
- Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
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Riordan DV. Mimetic Theory and the evolutionary paradox of schizophrenia: The archetypal scapegoat hypothesis. Med Hypotheses 2017; 108:101-107. [PMID: 29055381 DOI: 10.1016/j.mehy.2017.08.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 07/23/2017] [Accepted: 08/07/2017] [Indexed: 01/22/2023]
Abstract
Schizophrenia poses an evolutionary paradox, being genetically mediated yet associated with reduced fecundity. Numerous hypotheses have attempted to address this, but few describe how the schizophrenic phenotype itself might constitute an evolutionary adaptation. This paper draws on René Girard's theory on human origins, which claims that humans evolved a tendency to mimic both the desires and the behaviours of each other (mimetic theory). This would have promoted social cohesion and co-operation, but at the cost of intra-group rivalry and conflict. The mimetic dynamic would have escalated such conflicts into reciprocal internecine violence, threatening the survival of the entire group. Girard theorised that the "scapegoat mechanism" emerged, by which means such violence was curtailed by the unanimity of "all against one", thus allowing the mimetic impulse to safely evolve further, making language and complex social behaviours possible. Whereas scapegoating may have emerged in the entire population, and any member of a community could be scapegoated if necessary, this paper proposes that the scapegoat mechanism would have worked better in groups containing members who exhibited traits, recognised by all others, which singled them out as victims. Schizophrenia may be a functional adaptation, similar in evolutionary terms to altruism, in that it may have increased inclusive fitness, by providing scapegoat victims, the choice of whom was likely to be agreed upon unanimously, even during internecine conflict, thus restoring order and protecting the group from self-destruction. This evolutionary hypothesis, uses Girardian anthropology to combine the concept of the schizophrenic as religious shaman with that of the schizophrenic as scapegoat. It may help to reconcile divergent philosophical concepts of mental illness, and also help us to better understand, and thus counter, social exclusion and stigmatisation.
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Affiliation(s)
- Daniel Vincent Riordan
- West Cork Mental Health Services, HSE South, Bantry Hospital, Bantry, County Cork, Ireland.
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Orsolini L, St John-Smith P, McQueen D, Papanti D, Corkery J, Schifano F. Evolutionary Considerations on the Emerging Subculture of the E-psychonauts and the Novel Psychoactive Substances: A Comeback to the Shamanism? Curr Neuropharmacol 2017; 15:731-737. [PMID: 27834144 PMCID: PMC5771049 DOI: 10.2174/1570159x15666161111114838] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 05/24/2016] [Accepted: 10/03/2016] [Indexed: 01/21/2023] Open
Abstract
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.
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Affiliation(s)
- Laura Orsolini
- Psychopharmacology, Drug Misuse and Novel Psychoactive Substances Research Unit, School of Life and Medical Sciences, College Lane Campus, University of Hertfordshire, Hatfield, Herts, AL10 9AB
- Villa San Giuseppe Hospital, Hermanas Hospitalarias, Ascoli Piceno, Italy
- Polyedra Research, Polyedra, Teramo, Italy
| | - Paul St John-Smith
- Hertfordshire Partnership University NHS Foundation Trust, Civic Offices, Elstree Way, Borehamwood, Hertfordshire, WD6 1WA
| | - Daniel McQueen
- Child and Family Department, The Tavistock and Portman NHS Foundation Trust, Child and Family Department – 120 Belsize Lane, London, NW3 5BA & Eating Disorder Unit, Cygnet Hospital Ealing, 22 Corfton Road, Ealing, W5 2HT, UK
| | - Duccio Papanti
- Psychopharmacology, Drug Misuse and Novel Psychoactive Substances Research Unit, School of Life and Medical Sciences, College Lane Campus, University of Hertfordshire, Hatfield, Herts, AL10 9AB
| | - John Corkery
- Psychopharmacology, Drug Misuse and Novel Psychoactive Substances Research Unit, School of Life and Medical Sciences, College Lane Campus, University of Hertfordshire, Hatfield, Herts, AL10 9AB
| | - Fabrizio Schifano
- Psychopharmacology, Drug Misuse and Novel Psychoactive Substances Research Unit, School of Life and Medical Sciences, College Lane Campus, University of Hertfordshire, Hatfield, Herts, AL10 9AB
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15
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Srinivasan S, Bettella F, Mattingsdal M, Wang Y, Witoelar A, Schork AJ, Thompson WK, Zuber V, Winsvold BS, Zwart JA, Collier DA, Desikan RS, Melle I, Werge T, Dale AM, Djurovic S, Andreassen OA. Genetic Markers of Human Evolution Are Enriched in Schizophrenia. Biol Psychiatry 2016; 80:284-292. [PMID: 26681495 PMCID: PMC5397584 DOI: 10.1016/j.biopsych.2015.10.009] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 09/30/2015] [Accepted: 10/05/2015] [Indexed: 12/13/2022]
Abstract
BACKGROUND Why schizophrenia has accompanied humans throughout our history despite its negative effect on fitness remains an evolutionary enigma. It is proposed that schizophrenia is a by-product of the complex evolution of the human brain and a compromise for humans' language, creative thinking, and cognitive abilities. METHODS We analyzed recent large genome-wide association studies of schizophrenia and a range of other human phenotypes (anthropometric measures, cardiovascular disease risk factors, immune-mediated diseases) using a statistical framework that draws on polygenic architecture and ancillary information on genetic variants. We used information from the evolutionary proxy measure called the Neanderthal selective sweep (NSS) score. RESULTS Gene loci associated with schizophrenia are significantly (p = 7.30 × 10(-9)) more prevalent in genomic regions that are likely to have undergone recent positive selection in humans (i.e., with a low NSS score). Variants in brain-related genes with a low NSS score confer significantly higher susceptibility than variants in other brain-related genes. The enrichment is strongest for schizophrenia, but we cannot rule out enrichment for other phenotypes. The false discovery rate conditional on the evolutionary proxy points to 27 candidate schizophrenia susceptibility loci, 12 of which are associated with schizophrenia and other psychiatric disorders or linked to brain development. CONCLUSIONS Our results suggest that there is a polygenic overlap between schizophrenia and NSS score, a marker of human evolution, which is in line with the hypothesis that the persistence of schizophrenia is related to the evolutionary process of becoming human.
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Affiliation(s)
- Saurabh Srinivasan
- NORMENT, KG Jebsen Centre for Psychosis Research, Institute of Clinical Medicine, University of Oslo, Oslo, Norway,Division of Mental Health and Addiction, Oslo University Hospital, Oslo, Norway
| | - Francesco Bettella
- NORMENT, KG Jebsen Centre for Psychosis Research, Institute of Clinical Medicine, University of Oslo, Oslo, Norway,Division of Mental Health and Addiction, Oslo University Hospital, Oslo, Norway
| | - Morten Mattingsdal
- NORMENT, KG Jebsen Centre for Psychosis Research, Institute of Clinical Medicine, University of Oslo, Oslo, Norway,Division of Mental Health and Addiction, Oslo University Hospital, Oslo, Norway
| | - Yunpeng Wang
- NORMENT, KG Jebsen Centre for Psychosis Research, Institute of Clinical Medicine, University of Oslo, Oslo, Norway,Division of Mental Health and Addiction, Oslo University Hospital, Oslo, Norway,Multimodal Imaging Laboratory, University of California at San Diego, La Jolla, CA, USA
| | - Aree Witoelar
- NORMENT, KG Jebsen Centre for Psychosis Research, Institute of Clinical Medicine, University of Oslo, Oslo, Norway,Division of Mental Health and Addiction, Oslo University Hospital, Oslo, Norway
| | - Andrew J. Schork
- Multimodal Imaging Laboratory, University of California at San Diego, La Jolla, CA, USA,Cognitive Sciences Graduate Program, University of California, San Diego, La Jolla, CA, USA,Center for Human Development, University of California at San Diego, La Jolla, CA, USA
| | - Wesley K. Thompson
- Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA
| | - Verena Zuber
- NORMENT, KG Jebsen Centre for Psychosis Research, Institute of Clinical Medicine, University of Oslo, Oslo, Norway,Division of Mental Health and Addiction, Oslo University Hospital, Oslo, Norway,Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo and Oslo University Hospital, Oslo, Norway
| | | | | | - Bendik S. Winsvold
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway; Department of Neurology and FORMI, Oslo University Hospital, Ullevål, Oslo, Norway
| | - John-Anker Zwart
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway; Department of Neurology and FORMI, Oslo University Hospital, Ullevål, Oslo, Norway
| | | | - Rahul S. Desikan
- Multimodal Imaging Laboratory, University of California at San Diego, La Jolla, CA, USA,Neuroradiology Section, Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, CA, USA
| | - Ingrid Melle
- NORMENT, KG Jebsen Centre for Psychosis Research, Institute of Clinical Medicine, University of Oslo, Oslo, Norway,Division of Mental Health and Addiction, Oslo University Hospital, Oslo, Norway
| | - Thomas Werge
- Institute of Biological Psychiatry, Mental Health Center St. Hans, Mental Health Services Copenhagen, Roskilde, Denmark. Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark. The Lundbeck Foundation Initiative for Integrative Psychiatric Research, iPSYCH, Denmark
| | - Anders M. Dale
- Multimodal Imaging Laboratory, University of California at San Diego, La Jolla, CA, USA,Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA,Lilly UK, Erl Wood Manor, Windlesham, Surrey, UK,Department of Neuroscience, University of California at San Diego, La Jolla, CA, USA
| | - Srdjan Djurovic
- NORMENT, KG Jebsen Centre for Psychosis Research, Institute of Clinical Medicine, University of Oslo, Oslo, Norway,Division of Mental Health and Addiction, Oslo University Hospital, Oslo, Norway,Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
| | - Ole A. Andreassen
- NORMENT, KG Jebsen Centre for Psychosis Research, Institute of Clinical Medicine, University of Oslo, Oslo, Norway,Division of Mental Health and Addiction, Oslo University Hospital, Oslo, Norway,Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA,Corresponding author: , NORMENT, KG Jebsen Centre for Psychosis Research, Oslo University Hospital - Ullevål, Kirkeveien 166, PO Box 4956 Nydalen, 0424 Oslo, Norway; Tel.: +47- 22 11 98 90, Fax: +47- 22 11 98 99
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16
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van Dongen J, Boomsma DI. The evolutionary paradox and the missing heritability of schizophrenia. Am J Med Genet B Neuropsychiatr Genet 2013; 162B:122-36. [PMID: 23355297 DOI: 10.1002/ajmg.b.32135] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Accepted: 01/04/2013] [Indexed: 12/11/2022]
Abstract
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.
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Affiliation(s)
- Jenny van Dongen
- Department of Biological Psychology, VU University Amsterdam, Amsterdam, The Netherlands.
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17
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García-Montes JM, Pérez-Álvarez M, Perona-Garcelán S. Affinities in the phenomenological perspective of schizophrenia and recent cognitive research: Towards mutual enrichment. THEORY & PSYCHOLOGY 2012. [DOI: 10.1177/0959354312456600] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
This work presents affinities existing between the phenomenological view of schizophrenia and recent cognitive research on this disorder. We postulate that the core abnormality in schizophrenia is a particular kind of disturbance of the sense of self, which has two main aspects, an enhanced sense of awareness or hyperreflexivity, and diminished self-affection. Noticeable parallels are shown between “hyperreflexivity” and some cognitive models and research that concentrate on attentional processes in schizophrenia patients. It is also argued that “diminished self-affection” may be related to certain factors recently dealt with in cognitive research, such as “beliefs about superstition and responsibility related to one’s own thoughts” and “dissociation.” Furthermore, certain points which, in our opinion, could be of mutual enrichment to both viewpoints are briefly analyzed. Finally, several limitations and problems that such mutual sharing may have are also described, and some possible lines of future research are suggested.
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18
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Agnati LF, Barlow P, Ghidoni R, Borroto-Escuela DO, Guidolin D, Fuxe K. Possible genetic and epigenetic links between human inner speech, schizophrenia and altruism. Brain Res 2012; 1476:38-57. [PMID: 22483963 DOI: 10.1016/j.brainres.2012.02.074] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2011] [Revised: 02/29/2012] [Accepted: 02/29/2012] [Indexed: 11/19/2022]
Abstract
Unique mental abilities have been crucial for evolutionary success of Homo sapiens and for the development of his complex social organization. However, these abilities have also become a target for mental disorders which often result in a reduced fitness and in conflicts between the individual and the conventions of society. To account for this evolutionary maladaptation, we advance a new concept: that of "mis-exaptation", derived from SJ Gould and E Vrba's concept of exaptation. Mis-exaptation is a characteristic which, although it may confer positive effects in one field of activity, may reach an inappropriate degree of specialisation to have deleterious effects in that or in another field thereby leading to a decrease in fitness of the individual. This paper considers "inner speech" as an exaptation. Although inner speech is usually a positive aid to learning and reasoning, it may also favour the emergence of mental disturbances, such as the auditory hallucinations which are characteristic of schizophrenia. There is, nevertheless, a possible evolutionary value in mis-exaptational inner speech; two traits associated with the mis-exapted state would be altruistic behaviour and heightened creativity, the latter being over-expressed in relatives of schizophrenic patients. A possible solution for the evolutionary-genetic paradox posed by altruism and schizophrenia arising from mis-exaptation will be suggested in the light of a cryptic genetic repertoire. A selection of illustrative examples of each of these mental states is presented as they appear in the pages of the European literature. This article is part of a Special Issue entitled: Brain Integration.
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Abstract
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.
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Affiliation(s)
- Simon Dein
- Department of Mental Health Sciences, University College London, Charles Bell House, 67 Riding House Street, London WC1 7EY, UK.
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20
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Nesse RM. Ten questions for evolutionary studies of disease vulnerability. Evol Appl 2011; 4:264-77. [PMID: 25567972 PMCID: PMC3352562 DOI: 10.1111/j.1752-4571.2010.00181.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2010] [Accepted: 12/20/2010] [Indexed: 12/20/2022] Open
Abstract
Many evolutionary applications in medicine rely on well-established methods, such as population genetics, phylogenetic analysis, and observing pathogen evolution. Approaches to evolutionary questions about traits that leave bodies vulnerable to disease are less well developed. Strategies for formulating questions and hypotheses remain unsettled, and methods for testing evolutionary hypotheses are unfamiliar to many in medicine. This article uses recent examples to illustrate successful strategies and some common challenges. Ten questions arise in the course of considering hypotheses about traits that leave bodies vulnerable to disease. Addressing them systematically can help minimize confusion and errors.
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Affiliation(s)
- Randolph M Nesse
- Departments of Psychiatry and Psychology, Institute for Social Research, The University of Michigan Ann Arbor, MI, USA
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21
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Jansen A, Krach S, Krug A, Markov V, Eggermann T, Zerres K, Stöcker T, Shah NJ, Nöthen MM, Treutlein J, Rietschel M, Kircher T. A putative high risk diplotype of the G72 gene is in healthy individuals associated with better performance in working memory functions and altered brain activity in the medial temporal lobe. Neuroimage 2009; 45:1002-8. [PMID: 19167508 DOI: 10.1016/j.neuroimage.2008.12.054] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2008] [Revised: 09/08/2008] [Accepted: 12/17/2008] [Indexed: 01/14/2023] Open
Abstract
G72 is a vulnerability gene for schizophrenia and affective psychosis, disorders that are characterized by deficits in working memory. In the present study we investigated whether the G72 genotype influences verbal and spatial working memory functions in healthy individuals. Working memory was assessed at the behavioural level in 423 subjects using the spatial span of the Wechsler Memory Scale (spatial working memory) and the letter-number-span test (verbal working memory). In a sub-sample of 83 subjects, we assessed working memory functions also at the neural level using functional magnetic resonance imaging during a classical letter variant of the n-back task. Unexpectedly the high risk allele carriers performed better in the verbal working memory task than the other subjects. These behavioural differences were accompanied by brain activation differences in the right parahippocampus, a brain region that plays a major role in schizophrenia and affective disorders. The high risk variant of a vulnerability gene therefore does not necessarily have to negatively affect cognitive abilities per se, but may even have beneficial effects on cognitive functions in the non-affected population.
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Affiliation(s)
- Andreas Jansen
- Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Marburg, Germany.
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22
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Burns JK. Reconciling 'the new epidemiology' with an evolutionary genetic basis for schizophrenia. Med Hypotheses 2008; 72:353-8. [PMID: 19028022 DOI: 10.1016/j.mehy.2008.09.046] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Revised: 09/09/2008] [Accepted: 09/25/2008] [Indexed: 02/05/2023]
Abstract
Recent epidemiological findings of variable incidence and prevalence pose a problem for evolutionary genetic analyses of schizophrenia. The author rejects models of psychosis based on balanced polymorphism and develops an alternative evolutionary model incorporating concepts of anatagonistic pleiotropy, 'cliff-edged fitness' and gene-environment interactions. In essence, genes for psychosis are considered as 'normal genes' that play a fundamental role in neurodevelopment. A spectrum of genetic vulnerability exists in the population, which in the context of a toxic social environment is expressed as a continuum of psychosis. Complex bidirectional gene-environment interactions operate throughout neurodevelopment to mediate expression of the disorder. Harmful social conditions lead to epigenetic alterations in the expression of susceptibility genes/alleles. This in turn alters the trajectory of normal brain development resulting in abnormalities of neural connectivity, dysregulation of neurotransmitter and other biochemical systems, and resulting psychotic illness. In this manner, the evolved genetic make-up that defines the unique social cognitive abilities of modern Homo sapiens, also carries with it an inherent genetic vulnerability to harmful features of the social environment. Psychosis therefore, is not just a costly by-product of social brain evolution in modern humans, but is also a consequence of the unhealthy societies we create around us.
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Affiliation(s)
- Jonathan Kenneth Burns
- Department of Psychiatry, Nelson R Mandela School of Medicine, University of KwaZulu-Natal, Durban, 4000 South Africa.
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Pearlson GD, Folley BS. Schizophrenia, psychiatric genetics, and Darwinian psychiatry: an evolutionary framework. Schizophr Bull 2008; 34:722-33. [PMID: 18033774 PMCID: PMC2632450 DOI: 10.1093/schbul/sbm130] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The evolutionary origins of one of the most dramatic and seemingly deleterious behavioral phenotypes, the syndrome known as schizophrenia, are mysterious. Schizophrenia occurs in all cultures and is inherited. Although most phenotypes are said to be "selected for" based on adaptive qualities, it is difficult to understand how the genetic basis of schizophrenia could have operated under a similar framework. This has lead several theorists analyzing the proposed evolutionary origins of other disease states to that of schizophrenia. To date, several models have been applied. We have tried to conceptualize schizophrenia in a compensatory advantage framework whereby incomplete penetrance of the full disorder, or alternatively, the inheritance of risk alleles insufficient in number to manifest as the classic clinical syndrome, may manifest as a behavioral phenotype with adaptive advantages (eg, creative behavior or novel illuminating ideas). The idea that even full penetrance can also be advantageous has been offered as applied to religious experience and ancient social standing, but is unlikely. Can complex behavioral phenotypes such as schizophrenia, and particularly those that seem purely deleterious, be explained by mechanisms of Darwinian psychiatry? Can models from other disease classes be applied successfully to schizophrenia? Such ideas have generated intense speculation, but often in the absence of testable models. In this article, we will examine some of these proposed ideas and offer suggestions for future research.
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Affiliation(s)
- Godfrey D. Pearlson
- The Olin Neuropsychiatry Research Center, 200 Retreat Avenue, Whitehall Building, Hartford, CT 06106,Department of Psychiatry, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06510,Department of Psychiatry, Johns Hopkins University, 600 North Wolfe Street, Baltimore, MD 21287,To whom correspondence should be addressed; tel: 860-545-7757, fax: 860-545-7797, e-mail:
| | - Bradley S. Folley
- The Olin Neuropsychiatry Research Center, 200 Retreat Avenue, Whitehall Building, Hartford, CT 06106
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Debunking evolutionary psychiatry’s schizophrenia paradox. Med Hypotheses 2008; 70:1215-22. [DOI: 10.1016/j.mehy.2007.10.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2007] [Accepted: 10/06/2007] [Indexed: 11/22/2022]
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26
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Burns JK. Psychosis: a costly by-product of social brain evolution in Homo sapiens. Prog Neuropsychopharmacol Biol Psychiatry 2006; 30:797-814. [PMID: 16516365 DOI: 10.1016/j.pnpbp.2006.01.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/10/2006] [Indexed: 10/25/2022]
Abstract
The plethora of varied and often conflictual research evidence on the functional psychoses calls for a unifying explanatory framework. An evolutionary framework is appropriate in view of the paradoxical epidemiology of the disorders. Evolutionary models that rely on balanced polymorphism or group selection models are not supported by the evidence. Rather, a hypothesis is presented arguing that the spectrum of psychoses should be regarded as a costly by-product of social brain evolution in Homo sapiens. Under social selective pressures, hominid ancestors evolved a sophisticated neural network supporting social cognition and adaptive interpersonal behaviour--this is termed the 'social brain'. The functional psychoses (and schizophrenia in particular) are characterised by functional and structural deficits in these fronto-temporal and fronto-parietal circuits; hence the epithet 'social brain disorders' is fitting. I argue that accumulating evidence for an evolved social brain calls for a new philosophy of mind; a philosophy focussed on the social and interpersonal nature of human experience and derived from the philosophies of Fromm, Heidegger and Merleau-Ponty. Such a paradigm shift would aid modern neuroscience in finally abandoning Cartesian dualism and would guide psychiatry towards an integrated and 'socio-neurologically' embedded understanding of mental disorders.
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Affiliation(s)
- Jonathan Kenneth Burns
- Department of Psychiatry, Nelson Mandela School of Medicine, University of KwaZulu-Natal, Durban 4000, South Africa.
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27
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Abstract
OBJECTIVE Science needs to constantly match research models against the data. With respect to the epidemiology of schizophrenia, the widely held belief that the incidence of schizophrenia shows little variation may no longer be supported by the data. The aims of this paper are (i) to explore data-vs.-belief mismatch with respect to the incidence of schizophrenia, and (ii) to speculate on the causes and consequences of such discrepancies. METHOD Based on a recently published systematic review of the incidence of schizophrenia, the distribution of incidence rates around the world was examined. In order to examine if the incidence of schizophrenia differed by sex, male vs. female risk ratios were generated. RESULTS The distribution of incidence rates for schizophrenia is asymmetrical with many high rates skewing the distribution. Based on the central 80% of rates, the incidence of schizophrenia varies in a five-fold range (between 7.7 and 43.0 per 100,000). Males have a significantly higher incidence of schizophrenia compared with females (median male to female risk ratio = 1.4), and this difference could not be accounted for by diagnostic criteria or age range. CONCLUSION The beliefs that (i) the incidence of schizophrenia does not vary between sites and (ii) males and females are equally affected, may have persisted because of an unspoken deeper belief that schizophrenia is an egalitarian and exceptional disorder. Our ability to generate productive hypotheses about the aetiology of schizophrenia rests on an accurate appraisal of the data. Beliefs not supported by data should be identified and relabelled as myths.
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Affiliation(s)
- J J McGrath
- Queensland Centre for Mental Health Research, The Park Centre for Mental Health, Wacol, QLD 4076, Australia.
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28
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Wilson DR. Schizophrenia as one extreme of a sexually selected fitness indicator. Schizophr Res 2004; 70:111-4. [PMID: 15246470 DOI: 10.1016/j.schres.2003.10.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2003] [Revised: 09/28/2003] [Accepted: 10/28/2003] [Indexed: 10/26/2022]
Affiliation(s)
- Daniel R Wilson
- Department of Psychiatry, Creighton University Medical Center, 3528 Dodge Street, Omaha, NE 68131, USA.
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29
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Abstract
The term 'schizophrenia' refers to a group of disorders that have been described in every human culture. Two apparently well established findings have corroborated the need for an evolutionary explanation of these disorders: (1) cross-culturally stable incidence rates and (2) decreased fecundity of the affected individuals. The rationale behind this relates to the evolutionary paradox that susceptibility genes for schizophrenia are obviously preserved in the human genepool, despite fundamental reproductive disadvantages associated with the disorders. Some researchers have therefore proposed that a compensatory advantage must exist in people who are carriers of these genes or in their first-degree relatives. Such advantages were hypothesised to be outside the brain (e.g. greater resistance against toxins or infectious diseases), or within the social domain (e.g. schizotypal shamans, creativity). More specifically, T.J. Crow has suggested an evolutionary theory of schizophrenia that relates the disorders to an extreme of variation of hemispheric specialisation and the evolution of language due to a single gene mutation located on homologous regions of the sex chromosomes. None of the evolutionary scenarios does, however, fully account for the diversity of the symptomatology, nor does any one hypothesis acknowledge the objection that the mere prevalence of a disorder must not be confused with adaptation. In the present article, I therefore discuss the evolutionary hypotheses of schizophrenia, arguing that a symptom-based approach to psychotic disorders in evolutionary perspective may improve upon the existing models of schizophrenia.
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Affiliation(s)
- Martin Brüne
- Centre for Psychiatry and Psychotherapy, University of Bochum, Alexandrinenstr, Bochum, Germany.
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30
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Karagianis J. Re: Evolutionary perspectives on schizophrenia. CANADIAN JOURNAL OF PSYCHIATRY. REVUE CANADIENNE DE PSYCHIATRIE 2003; 48:641. [PMID: 14631886 DOI: 10.1177/070674370304800916] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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