Schizophrenia Research Trends

Evolution and Schizophrenia 123derives benefit. In humans, competition between tribes presumably resulted in group-leveladaptations. Thus, individuals, kin or tribes can be the beneficiaries of adaptive traits.Individual AdvantagesThere are only two hypotheses suggesting that some advantage resides inside theindividual with schizophrenia that counterbalances its disadvantages – both hypotheses aremore for historical interest. The Huxley et al paper has already been introduced. The secondhypothesis was formulated by J.M. Kellet in 1973 [57]. It suggested that characteristicsassociated with schizophrenia could have helped early man’s territorial instincts, whereasaffective disorders would have assisted negotiating hierarchal tensions. Schizophrenia traits,such as inventiveness and the ability to tolerate low levels of stimulation while remainingalert, would have been advantageous to territorial animals. Kellet’s hypothesis, however,addresses only a small component of schizophrenia, providing no evolutionary explanationfor psychotic symptoms. Further, the social structure of Homo sapiens lineages is bettercharacterized as hierarchal instead of territorial.Advantages to KinThere have been three major hypotheses suggesting that relatives of patients withschizophrenia are the ones that accrue the evolutionary advantages associated with theillness. Studies by Karlsson found superior academic success among relatives of patients withschizophrenia [58]. Accessing records from Iceland’s stable population and using diversemethods to measure creative intelligence strengthened confidence in the results. Karlssonexplain his results using the balanced polymorphism model – suggesting that creativerelatives of schizophrenia patients are super-adaptive heterozygotes. Although not anevolutionary hypothesis per se, Karlsson’s work could perhaps explain the persistence of theschizophrenia genotype.The relationship between insanity and exceptional ability, in afflicted individuals or theirrelatives, has been a frequent theme through history and in Western culture dates back toAristotle [59]. Several remarkable personal accounts are known – Isaac Newton becamepsychotic at age 51 years, and Albert Einstein’s son was diagnosed with schizophrenia [60-61]. Other notable examples include Nobel laureate John Nash, who developed schizophreniain his early 30’s and Bertrand Russell, who apparently had several relatives withschizophrenia. Perhaps, a more convincing connection exists with affective disorders [62].One recent review suggested little evidence exists to link creativity and mental illness [59].However, the author failed to fully appreciate the discernible bias against making aconnection – historical references to mental illness will always be underreported whileachievements are without exception widely recognized. The author dismissed even reputablework such as Karlsson’s Icelandic study solely because it was of retrospective design.Furthermore, if psychiatric conditions were responsible for only a fraction of alldemonstrations of creativity, proving an association would be difficult.Allen and Sarich [63] postulated that the “ schizophrenia advantage is in the somewhattouchy relationship between an individual and his culture and society”. Using the balancedpolymorphism argument, overt schizophrenia or having no genetic loading for schizophreniawould be non-adaptive. Asymtomatic heterozygotes, perhaps 5%, with some genetic loading