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torsdag den 10. maj 2012

Orkidé-hypotesen - og generne for særligt følsomme personligheder - og for depressioner

De fleste populære bøger om kreativitet hævder at vi alle er eller kan være kreative. Det er typisk bøger som skal hjælpe folk på arbejde og i særlige former for job hvor kravet om nye ideer er indbygget i rollen, til at klare sig bedre.
   Men det passer utvivlsomt ikke. Kreativitet er er produkt af hjernens konstruktion og funktion, og den konstruktion kan variere fra person til person ligesom folks kropshøjde, hårfarve og mange andre biologiske og fysiologiske egenskaber. En variation som grundlæggende skyldes vores genetiske lægning.
  Kreativitet er altså i et eller andet omfang - ganske stort sandsynligvis - genetisk bestemt - og dermed arveligt.

Det er nemt at finde abstracts fra videnskabelige artikler som underbygger det:
Why are genetic polymorphisms related to severe mental disorders retained in the gene pool of a population? A possible answer is that these genetic variations may have a positive impact on psychological functions. Here, I show that a biologically relevant polymorphism of the promoter region of the neuregulin 1 gene (SNP8NRG243177/rs6994992) is associated with creativity in people with high intellectual and academic performance. Intriguingly, the highest creative achievements and creative-thinking scores were found in people who carried the T/T genotype, which was previously shown to be related to psychosis risk and altered prefrontal activation.
This comparative study of Icelanders, born during the period 1881–1910, indicates that close relatives of psychotic individuals have a significantly increased probability of being considered persons of eminence. Their rate of listing in Who Is Who is doubled, both in regard to general listings and those based on artistic or scholastic endeavors. Review of relevant literature supports the view that the dominant principal gene proposed for schizophrenia may in a heterozygous state lead to cerebral stimulation, with improved  performance in areas of giftedness and creativity.   
http://onlinelibrary.wiley.com/doi/10.1111/j.1601-5223.1970.tb02343.x/abstract
Mange undersøgelser peger i retning af at nogle gener disponerer for både skizofreni og det at være særligt kreativ. Hvad det så er der i anden omgang bestemmer at det går den ene eller anden vej, er ikke klart. Men en af hypoteserne er at den afgørende forskel er de kognitive kontrolfunktioner som udøves af den del af hjernen som kaldes prefrontal cortex. 
If we could identify a gene for creativity, let's call it the "creativity gene", you would be hard pressed to find very many people who would consider it a "negative gene" or a hazard to possess or carry. But what if, purely hypothetically, we could identify a gene for Schizophrenia? Or Bipolar Disorder? Or Depressive Disorder? Or ADHD? Would you select for those traits if you could genetically engineer your offspring at will? If you wanted to give birth to a creative child, the answer should be yes.
   The very traits that make someone creative, passionate, and likely to achieve a high degree of success in their domain, are the same traits that define psychological disorders such as Bipolar Disorder, Schizophrenia, and ADHD. So what is the difference between creativity and psychopathology? Where do we draw the line between functional excess of extreme traits and the point at which they define a psychological disorder? Is there a discriminating characteristic that separates these two groups? Yes, there is, and it's called cognitive control, or high executive function.  
En beslægtet diskussion udfolder sig videnskabeligt omkring noget der nok så poetisk kaldes "orkidé-hypotesen". Den tager afsæt i at en kombination af gener tilsyneladende disponerer for den personlighedstype som jeg tidligere har omtalt: HSP - den hypersensitive personlighed, en personlighedstype der er sårbare som "orkider" og kræver megen varme og omsorg for at blomstre - og som ellers nemt mentalt og socialt går i hundene. 

I følgende citat sættes HSP´erne i modsætning til den robuste personlighedstype - "mælkebøtten" ("dandelion") - som kan slå rod, klare sig og blomstre under de mest besværlige og ufrugtbare vilkår:
Most of us have genes that make us as hardy as dandelions: able to take root and survive almost anywhere. A few of us, however, are more like the orchid: fragile and fickle, but capable of blooming spectacularly if given greenhouse care. So holds a provocative new theory of genetics, which asserts that the very genes that give us the most trouble as a species, causing behaviors that are self-destructive and antisocial, also underlie humankind’s phenomenal adaptability and evolutionary success. With a bad environment and poor parenting, orchid children can end up depressed, drug-addicted, or in jail—but with the right environment and good parenting, they can grow up to be society’s most creative, successful, and happy people.
http://www.theatlantic.com/magazine/archive/2009/12/the-science-of-success/7761/
I det følgende citat kobles den kendsgerning at depression er noget man genetisk er disponeret for, sammen med orkidé-hypotesen. Depression er ikke forudsætningen for kreativitet sådan som nogle hypoteser har gået ud på at sammenhængen er. Men kreativitet kan udspringe af de samme "overfølsomhedsgener" som depressioner - hvis omverdenen er mild og varm og uden stressvilkår:
The question of depression generating insight leads inevitably to the much-discussed (and sometimes disputed) association between depression and creativity. Does depression, either unipolar or bipolar, generate creativity? There’s some evidence it does. There are links. But what’s the source of the link?
   Well, depression might, as above, sometimes directly inspires introspection and insights contributing to creativity. That’s a direct causal relation.
   But I think that some attributing creativity to depression may, in some cases and perhaps in general, mistake association for cause — that depression is not the thing that generates creativity and insight but a byproduct of another trait that does. And that this other trait is sensitivity — and particularly the sensitivity that comes from the “sensitivity” genes I recently wrote about in The Atlantic.
   The sensitivity hypothesis asserts that some gene variants presently considered “risk genes” for mental health problems in people with stressful lives are actually “sensitivity genes” that make you more sensitive to all experience. One of the genes in question is the serotonin transporter gene, or SERT gene, which helps regulate the neurotransmitter serotonin. Two of the three variants of this gene (the “short-short” or s/s version and the “short-long” or s/l versions) have been shown to put people with stressful life histories at greater risk for depression. The sensitivity or orchid hypothesis asserts that these short SERT variants don’t make people more sensitive to bad experience but to all experience, bad or good. It’s not a “depression gene” but a sensitivity gene. What you make of that sensitivity naturally depends on other assets or experiences you have.
   If this is so, then it’s possible that this sensitivity hypothesis may account (wholly or in part) for findings that “depressed people” have more insights or creativity — only it’s not necessarily the depression that generates the insight, it’s the heightened sensitivity. http://www.wired.com/wiredscience/2010/03/does-depression-have-an-upside-its-complicated/
Når jeg kom på sporet af denne orkidé-hypotese og dens kobling til den genetiske sammenhæng mellem kreativitet og forskellige former for genetiske betingede personlighedsforstyrrelser, så skyldes det en Facebook-henvisning fra videnskabsjournalisten Lone Frank, som medvirkede i et australsk radioprogram hvor temaet blandt andet var den genetiske sammenhæng mellem depression og hypersensitivitet.
   Krogen var Lone Franks bog "Mit smukke genom" som også er oversat til engelsk. Hun bruger  i den sig selv som frendriftgivende plot og får undervejs kortlagt sit genom der bl.a. viser at hun er disponeret for depression og mental sårbarhed.
   Citat fra bogens indledende kapitel:
„Det er ikke, fordi jeg nyder at sige det, Lone,“ sagde en velmenende studiekammerat for mange år siden,  „men du har din personlighed imod dig.“ Det var sjovt nok på nogenlunde samme tid, hvor en amerikanskveninde kaldte mig hudløst ærlig. En bedømmelse der gjorde mig helt varm indeni, lige indtil hun satte hænderne i siden og råbte:  „Det er brutalt! Fatter du da ikke, at folk afskyr ærlighed?“
   Men hvor meget af den åbenbart utiltrækkende personlighed og af min psyke i det hele taget kan jeg tørre af på nogle bitte små variationer indskrevet i mit DNA? Er det kombinationen af en håndfuld uheldige gener fra  to familier, der giver mig tilbagevendende depressioner og et konsekvent sortsyn? Eller stammer begge dele fra en til tider udfordrende opvækst med et par forældre, der altid var i totterne på hinanden, indtil de afsluttede samlivet med en grim skilsmisse? 
Jeg har vist tidligere skrevet at Lone Frank utvivlsomt hører til den særligt kreative personlighedstype - og har haft den type belastende opvækst med mentale tab og savn som også er typisk for mange meget kreative mennesker.

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