Distorted View:
Artist's interpretation of schizophrenia, which has hereditary features that are hard to elucidate.
Image: M. Kulyk Photo Researchers, Inc.
-
The Best Science Writing Online 2012
Showcasing more than fifty of the most provocative, original, and significant online essays from 2011, The Best Science Writing Online 2012 will change the way...
Read More »
Schizophrenia hides its heritability well. Although fewer than 1 percent of the general population will be diagnosed as schizophrenic based on symptoms such as hallucination and disorganized thought, for children of a schizophrenic parent, those odds jump to about one in 10. And yet the condition’s genetic underpinnings have stubbornly resisted discovery. In the latest attempt, three crack teams of investigators pooled genomic data from 8,000 schizophrenics of European ancestry but could lay claim to only a handful of weak genetic risk markers.
Analyses such as these, which appeared online July 1 in Nature (Scientific American is part of the Nature Publishing Group), have led researchers to question the value of brute-force genomics for analyzing schizophrenia. “I think we need to pause and think through the risk pathways to disease more clearly,” says Dolores Malaspina, director of the social and psychiatric initiatives program at New York University Langone Medical Center. In particular, devotees of genetics might want to cede a little ground to their colleagues in epidemiology, who over the past decade have amassed a provocative, interlocking set of studies implicating urban birthplace and migrant status as persistent risk factors.
Researchers believe the potential for schizophrenia starts to emerge during early brain development, beginning in the womb. Rates tick up slightly for offspring whose mothers were infected with influenza or undernourished during pregnancy, for newborns who suffered obstetric complications such as oxygen deprivation, and for offspring born in the winter or spring.
Starting in the 1990s, studies from Denmark, the Netherlands and Sweden began making the case for urban life as a distinct risk factor. In the largest of these, out of a cohort of 1.75 million Danes, being born in Copenhagen was associated with a 2.5-fold greater risk of schizophrenia than being born in rural areas. Danes who were born in smaller cities showed intermediate risk. Although the nature of the exposure remains obscure, researchers were able to narrow down its timing: Danes who lived in urban centers for the first 15 years of life had the most elevated risk.
A second wave of findings has documented that immigrants to European countries are at heightened risk of schizophrenia as compared with native-born residents. Second-generation immigrants show increased risk relative to their parents, and rates are highest among those of African heritage. In a study of three cities in the U.K., Afro-Caribbeans were nine times as likely as the general population to be treated for schizophrenia. Neighborhood composition seems to play a role. In South London epidemiologist James Kirkbride of the University of Cambridge and his colleagues at King’s College London have found that in neighborhoods with higher measures of “social cohesion,” such as voter turnout, the incidence of schizophrenia is proportionally lower.
Despite the consistency of the findings, epidemiologists who work in the field say scientific journals in the U.S. have shown reluctance to consider papers that explore the relation between race and schizophrenia. Hence, it was not until 2007 that Michaeline Bresnahan, Ezra Susser and their colleagues at the Columbia University Mailman School of Public Health cautiously published data from a cohort of 12,000 Californians enrolled in the Kaiser Permanente health plan, which showed that the rate of hospital admission for schizophrenia was twice as high for African-Americans as for whites, even after controlling for socioeconomic status of the parents. Because the cohort was part of the same health plan, reduced access to health services was unlikely to account for the discrepancy, Susser says.
Given that schizophrenia has no clear biological markers, skeptics may question whether diagnostic criteria have been applied rigorously across diverse cultural groups. For epidemiologists, such arguments miss the point. “The strategy is to identify important risk or protective factors within a given group,” observes Dana March, a Ph.D. candidate in Susser’s group.
See what we're tweeting about
18 Comments
Add CommentSo...
Reply | Report Abuse | Link to thisGood genes...make better kids.
It's common for people with the same emotional problems to have children together.
What's environmental about that.
There is no Oakland County in California; the City of Oakland is in Alameda County.
Reply | Report Abuse | Link to thisShel Carroll, San Jose, CA
Look up this 2009 Harvard study entitled:
Reply | Report Abuse | Link to thisRelation of Schizophrenia Prevalence to Latitude, Climate, Fish Consumption, Infant
Mortality, and Skin Color: A Role for Prenatal Vitamin D Deficiency and Infections? by Kinney et al.
The reference to 'migrant status' is too oblique -- we are not talking about Swedes moving to Spain but rather people with darker skin moving further away from the equator.
Vitamin D deficiency is common in dark skinned immigrants to high latitude countries for the simple biological and non-racist reason that dark skins do not generate as much vitamin D per unit sunshine as light skin.
It is also well documented that urban populations tend to get less exposure to the sun than rural and tend to have a higher rate of vitamin D deficiency.
I was frankly surprised to find no mention of the vitamin D deficiency hypothesis as a contributor to schizophrenia in this article.
Is it possible that schizophrenia stems simply from inadequate pattern-matching capabilities? An incorrect match would thereby trigger a halucination, being simply the wrong sensoriel image being selected?
Reply | Report Abuse | Link to thisTalk about poorly formed questions. "What causes schizophrenia?" is on par with "What causes traffic accidents?"
Reply | Report Abuse | Link to thisCongrats SciAm - no detail, poor grammar and a geographical error in one story.
Reply | Report Abuse | Link to thisDoes anyone proof-read or fact check?
The minor errors in the articles copy do not invalidate its contents. As a mental health worker for the past 46 years, I found the article to be interesting and informative.
Reply | Report Abuse | Link to thiseco-steve at 09:42 AM on 11/17/09
Reply | Report Abuse | Link to thisIs it possible that schizophrenia stems simply from inadequate pattern-matching capabilities? An incorrect match would thereby trigger a halucination, being simply the wrong sensoriel image being selected?
I think you got something there.
There is one old saying that comes to mind here. "If the brain was so simple we could understand it, we would be so simple we couldn't." The introduction of the concept that the environment may be more important than we think is indeed valid. However, the genetic component is real as acknowledged.
Reply | Report Abuse | Link to thisThis situation may prove to be most instructive. Genes are far more complex than anticipated. They work as a team and in a manner that eludes us to date. They respond to the environment - as they must. They take care of trillions of cells. With respect to the brain, genes and 'dysfunction', we are face to face with a remarkably sophisticated network that defies our attempt(s) to identify 'cause and effect'. I suggest that these efforts are (correctly) well intentioned but the brain is simply far beyond us at this point. We might get there - millions of years from now ...
Nature and Nurture intersect. What is so surprising? If you take someone who has a potential problem, and put them in a crowded, poorly educated environment, filled with violence, why would you be surprised if the outcome is mental illness; as opposed to putting them in a serene well nourished atmosphere where they might have a more reasoned response to their problems?
Reply | Report Abuse | Link to thisVitamin D deficiency, infection, and stress might suppress neurogenesis, leading to symptoms of depression, anxiety, schizophrenia, or other 'mental illnesses.'
Reply | Report Abuse | Link to thisExcerpt from http://seedmagazine.com/content/print/the_reinvention_of_the_self/ :
"For example, if a pregnant rhesus monkey is forced to endure stressful conditionslike being startled by a blaring horn for 10 minutes a dayher children are born with reduced neurogenesis, even if they never actually experience stress once born. This pre-natal trauma, just like trauma endured in infancy, has life-long implications. The offspring of monkeys stressed during pregnancy have smaller hippocampi, suffer from elevated levels of glucocorticoids and display all the classical symptoms of anxiety. Being low in a dominance hierarchy also suppresses neurogenesis."
A propos: nurture re schizophrenia: nutritional i.e. vitamin deficiencies may well play a part in triggering onsets of schizophrenia; this applies specifically to migrants from sunnier climates with fruits aplenty who often lack their traditional food intake patterns in their northern host countries, which can cause nutritional starvation mode for the brain, with probable malfunctions such as schizophrenia and depression as consequence.
Reply | Report Abuse | Link to thisThere's no mention of the many who unexpectedly develop severe schizophrenia shortly after puberty.
Reply | Report Abuse | Link to thisAdult-onset schizophrenia devastates families with its sudden arrival, affecting those who were perfectly normal as a child and teenager.
See http://DrMcKenzie.com for one of the major factors in experiencing schizophrenia, early trauma. His textbook link at amazon.com is: http://www.amazon.com/exec/obidos/ISBN=9057025019/recoverybydiscovA/
Reply | Report Abuse | Link to thisadfhsteh
Reply | Report Abuse | Link to thisRisk factor? Horror story!
Reply | Report Abuse | Link to thisDeaf son. Hallucinating and paranoid (command / control issues). Did not recognize his mom or dad. 15 y.o.
Could not get him into a treatment facility for 2.5 days!
Then a psychiatrist made arrangements for him to get into LI Jewish Memorial hosp where the truth be told, they had no idea if that was a proper diagnosis.
Since, he been diagnosed depressed and now, finally, ADD!
He had grown 4 inches in he space of 5 months! He had major kidney surgery (UPJ obstruction) and a broken toe 3 months prior.
Why am I sending this? I hope someone can use this info to prevent disabled kids from further deterioration and anxiety. I believe the main reason it happened was he was alienated and had the risk factors: born in late Nov., lived in NYC for a few years, mainstreamed school (a lot of pressure).
But let's not forget he is not dark skinned. I would like to believe his height change and internal pressures "snapped" him.
Is there a snap gene?
Am I being silly "bugging" about science looking in a skin color direction when there are "non-colored" components, me being one of those voices?
You want to write an impressive article? Why do the professional "front line" doctors tell me , '...the northeast is notoriously poor at diagnosis, treatment and support of adolescent neuroses.'?
Then throw a disability on?
The one doctor that was going to take us would NOT provide for a deaf child!
Where are the doctors espousing 'inability to cope" and hormone changes?
European? Vitamin D? Possible.
Dr. Feynman, rest his soul, said a long time ago, 'We scientists look in our own directions for answers. Then some day, we get a call from a colleague telling us to look over here. So we put down what we're doing and try to get back to it later'...paraphrasing all the way, but you get the gist.
I believe your latest viewpoint is awaiting a much needed update...
At least, for the layman it seems easy to call this latest effort mumbo-jumbo, premature at best.
Constant Stress as Schizophrenia Trigger?
Reply | Report Abuse | Link to thisI wonder if anyone ever studied the impact of long period stress factor as a possible schizophrenia trigger ?
I mean such factors as :
- Noisy, crowded city environment, with continuous sensory stimulation.
- Prejudiced, unfriendly people around
- Lower self esteem
It is possible that human brain exposed to such long term stress factors may experience some specific modifications, which end up as schizophrenia in some more prone people.
It would be interesting to study what is the impact of migration for people who experience a good assimilation and much better life quality in the new country.
It could be that higher risk of schizophrenia among people of African origin can be attributed to two factors :
- evolutionary : in Europe more people, for longer periods lived in overcrowded urban communities, so people more resistant to stress linked to such life conditions could be more favored by evolution. (ex. people more stressed more easily get infections, and by having a weakened immunity system, are more likely to die and leave less progeny)
For the most of its history Africa was less urbanized, so people living there had no chance to evolve a higher psychical hardiness to difficulties and stresses linked with the life in the overcrowded urban environment.
- since Afro-Americans are in minority and in general they experience worse economic and social status, this may be the cause of a life-long stress and lower self esteem.
It should be compared what is the frequency of schizophrenia among people living a placid life in calm, friendly environment when compared to people exposed on overwhelming sensory stimulus, neighborhood hostility, insecurity, stressful work.
Ask and ye shall receive: http://www.scientificamerican.com/article.cfm?id=more-vitamin-d-could-prevent-some-psychosis
Reply | Report Abuse | Link to this