White Bears, Written Words

What did you get for Christmas, maybe you got a book? As books are one of the most popular Christmas gifts we ask in today's article "Can Reading Harness Brain Plasticity?"

“Once upon a time in Uzbekistan” is not a way that many neuroscience stories begin. But for this issue on nature and nurture, a key narrative began there that would come to influence debates up to the present day.
Alexander Luria, a Soviet neuropsychologist keenly interested in the relationship between culture and the mind, studied the influence of literacy on styles of argumentation. He wanted to test whether cultural experiences could affect thought patterns. By working with illiterate peasants, he uncovered fascinating examples of how written language seemed to be necessary for abstract thought patterns. His most famous example went something like this:

Luria: “In the North, there is snow, and all bears are white. Novaya Zemlya is in the far North. What color are the bears there?”

Peasant: “I don’t know. I’ve never been to the far North. I saw a black bear here once.”

Many more such examples (dealing with everything from describing shapes to objects to self-reference) were collected in Luria’s bestseller, Cognitive Development: its Social and Cultural Foundations [1]. It went on to be a fundamental text in both neuroscience and anthropology.

via Wikimedia Commons

Putting Text in Context
Although literacy has developed too recently to alter the human genome, it is an integral part of most human societies. For example, if you are on your computer today, you will probably scan more than 500,000 words (not to mention what you see in your time offline) [2]! Furthermore, the practice of reading makes a fascinating case study for the effect of a very special type of nurture on the brain.
Reading text is a multimodal exercise, incorporating visual, auditory, and cognitive/predictive elements of language comprehension. Luria argued (and many today agree) that reading was necessary to provide a scaffold for certain types of abstract thought [1,3]. While fascinating on a purely ethnographic basis, studies such as these still leave many questions to ponder. Though literacy underlies many human interactions, it has only developed on a widespread basis in the last few hundred years. Could this relatively new type of cognitive processing be sufficient to make changes in our brain?

Reading the Signals from Neuroimaging
The hills of Uzbekistan are distant from the labs of today, and indeed, so are the approaches that are used. Although many groups worldwide still do not use written language, they generally aren’t accessible with an MRI scanner in tow. So what do we do now?
Today, our primary knowledge about the effects of reading on the brain comes from longitudinal studies in school-age children. These studies [cf 4,5] demonstrate that literacy appears to co-opt pre-existing language networks in the brain. Notably, the left superior temporal sulcus and inferior frontal areas show robust activation, correlating well with development of reading abilities. These findings are intriguing, but not entirely conclusive. In the countries where these studies were performed, children are legally obligated to go to school and receive formalized instruction. Therefore, a non-literate control group cannot be used to provide more definitive answers about the effects of literacy on the brain.

by Mark Larson via Flickr, "Use your library often!"

Recently, researchers have found a way around these challenges, to examine the development of reading skills in a more controlled setting. For example, a group in France has published a set of studies examining the neural correlates of the development of literacy in adults. Essentially, the scientists scanned the brains of adults who had learned to read in childhood using diffusion tensor imaging. They compared them with the brains of adults who had only recently acquired literacy skills. Vast tissue tracts were affected, with literacy acquisition leading to elaboration of tempero-parietal connectivity [6].
A separate study which compared two groups of illiterate adults, one of which received a reading intervention program, found evidence of reading-mediated changes in early visual processing [7]. Other evidence of literacy’s effects on the brain come from people who have reading disorders such as dyslexia. These individuals, contrary to their normally-reading peers, have been shown to demonstrate hypoactivation of several superior temporal areas typically associated with word processing and semantic retrieval [8,9]. Taken together, this work suggests a tightly interlinked series of regions in the brain that are altered through learning to read and whose malfunction may underlie a failure to do so.

Literacy: A Thoroughly Complicated Business
So can we still stand by Luria 80 years later? Yes and no. Although it appears that literacy skills do foster changes in activation and connectivity, we are still a long way from understanding how these changes might underlie certain types of abstract thought (and beliefs about polar bears). Moreover, there are several obstacles to getting the full picture about reading and the brain. At the end of the day, reading is a fundamentally culture-bound phenomenon. It is deeply influenced by the values and educational emphases of the society in which it develops.
As neuroimaging studies progress, we should not forget where all these questions started. Though a trip through the wilderness is certainly not for the faint of heart, it may still be the best way to integrate neuroscientific, ethnographic, and linguistic inquiry. And with a business as complicated as understanding literacy, it may be where we need to return.

[1] Luria, Cognitive Development: Its Cultural and Social Foundations, 1976
[2] Bunz, “Is the link economy of UK news sites managing or making abundance?” in PDA: The digital content blog, Nov 2, 2009
[3] Nell, Neuropsych Rev, 1999
[4] Berl et al, Brain Lang, 2010
[5] Horowitz-Kraus et al, Front Hum Neurosci, 2014
[6] de Schotten et al, Cereb Cort, 2014
[7] Boltzmann and Rüsseler, BMC Neuroscience, 2014
[8] Christodoulou et al, PloS One, 2014
[9] Eicher and Gruen, Mol Genet Metab, 2013

by Constance Holman, PhD Student AG Schmitz
This article originally appeared 2014 in CNS Volume 7, Issue 3, Nature vs Nurture 

Tracing the Roots of Aggression

Many evolutionary theories explain the development of human aggression as a necessary trait for survival. However, aggression rarely has practical use in contemporary society. When exhibited, it is often in a violent and illegal context and therefore it is incriminated. Sometimes, it can even be considered part of someone’s temperament.

Aggression is thought to be the result of a complex corticolimbic interaction between subcortical neural systems, decision-making circuits, and frontoparietal regions [1]. Strong genetic and hormonal influences, in addition to the various environmental stimuli, seem to regulate these networks. This raises questions regarding the degree of responsibility that violent people bear.

Aggression Is a Male Phenomenon
According to statistics, the ratio of crimes committed by males compared to females is greater than 10:1. The more aggressive behavior of males starts to manifest itself even before adolescence, with boys being more likely to be involved in some kind of antisocial conduct [2].
Hormones are among the first suspects for male aggression. Exposure to androgens in the early stages of adolescence is thought to constitute a possible cause. However, according to a recent meta-analysis, the association between testosterone levels and antisocial behavior is weak [3]. Next is the stress hormone cortisol, whose action is regulated through the hypothalamus and adrenal axis. Lower cortisol concentration was found in the saliva of males with antisocial conduct [4]. Finally, low levels of the serotonin metabolite 5-HIAA and low blood sugar are other messengers implicated in the regulation of aggressive behavior.

Is It You Y?
More than four decades have passed since males with XYY syndrome, known also as supermales, were associated with criminal behavior. A higher percentage of XYY men was found in prisons and in institutions for criminally insane people than was found among the normal population. This hypothesis has been significantly weakened after the publication of epidemiological studies that suggested otherwise [5], although it has not been totally refuted as emerging evidence still supports the initial claim [6].
Taking a closer look at the genes, recent knockout studies in mice have excluded any contribution of the Y-linked loci to aggression [7]. Nevertheless, the investigation of other chromosome loci revealed genes that might explain the sex-related difference in aggression and should be interpreted along with the hormone hypothesis. A shorter GAG repeat in the Androgen receptor in Swedish and Indian males accused of aggressive behavior has been associated with it [8]. Certain polymorphisms of the monoamine oxidase (MAOA, MAOB)-coding genes have been linked with functional differences in expression. A plethora of enzyme-coding genes (COMT, dopamine-β-hydroxylase and tryptophan hydroxylase) has been linked to male aggressive behavior [9].

Environmental Interactions
Stressful events, especially in the first years of life, confer a higher risk for manifesting antisocial conduct. Interestingly, it seems that stress triggers aggressive behavior in males with a “vulnerable” genetic background and more specifically a low-activity polymorphism in the MAOA gene. The causality in this case is not clear yet, as evidence suggests that an initial stressful event down-regulated the activity of the MAOA genes later on [2].

The Role of Recreational Substances
Substance use is closely related to offending behavior in both sexes, with alcohol being the most common culprit. It is not only widespread alcohol use, but also its high correlation with violent behavior that make it one of the most significant perpetrators of aggression. Drug users on the other hand, rarely exhibit such behavior, with cocaine users being the only exception [10]. 
Aggressive behavior, like every behavior, is difficult to approach and explain with molecular and genetic mechanisms. However, there seems to be a notable interaction between the environment and one's genetic background. This requires further investigation, as the potential implications for preventing the development of an aggressive behavior, even in a small portion of the population, could improve dramatically the fabric of our societies.

[1] Coccaro et al, Biol Psychiatry, 2011
[2] Craig and Halton, Hum Genet, 2009
[3] Book et al, Aggress Violent Behav, 2001
[4] Shirtcliff et al, Dev Psychopathol, 2005
[5] Noël et al, Clin Genet, 1974
[6] Stochholm et al, BMJ Open, 2012
[7] Gatewook et al, J Neurosci, 2006
[8] Rajender et al, Int J Legal Med, 2008
[9] Pavlov et al, J Appl Genetics, 2012
[10] Lammers et al, Tijdschr Psychiatr, 2014

by Andreas A. Diamantaras, MSc student
This article originally appeared in CNS Volume 7, Issue 3, Nature vs Nurture

Can You Raise Your Kids Gay?

Over the years, the controversy of the nature versus nurture debate has extended beyond childhood behavior to intelligence and also sexual preference. Today's article aims at uncovering the roots of male homosexuality.

digitalart / FreeDigitalPhotos.net

On July 16th 1993, the Daily Mail ran the headline: "Abortion hopes after the 'gay genes' findings". The author, Jason Lewis, claimed that, thanks to recent advances, it might soon be possible to predict the sexual orientation of a baby and give parents the option of abortion. Irrespective of the intentions of the author and possible implications of this article, let us first consider whether this will ever be possible. Since male homosexuality is much more common in nature than female homosexuality, most of the research on sexual orientation concerns only male homosexuality. Years into research on the topic, scientists cannot give a conclusive answer to the question of reasons for our sexual orientation. Simply put, it does not exist.

The Evolutionary Mystery
Homosexual behavior is natural in the animal world, with over 1500 species practising it [1]. Does this give us a first clue that biological factors play a crucial role in establishing sexual orientation? Possibly. In 1991, a twin study conducted by Michael Bailey and Richard Pillard showed that among monozygotic male twins, one gay brother increased the probability of the second being gay by up to 52% [2]. In contrast, this percentage was as low as 22% for dizygotic twins and 11% for adoptive brothers. Hamer and colleagues proposed that an Xq28 allele influences sexual orientation, as its sharing between gay brothers was 64%, not 50% as would be expected by chance [3].

Over 1500 species practice homosexual behaviors

Yet, evolution would intuitively not promote a gene that is anti-reproductive. Why would it then survive in our population at all? The hypothesis here is simple and elegant – the gene that in males promotes homosexuality, in females contributes to their fecundity. Families with homosexual members have been shown to reproduce more than those without  [1]. We must, however, note that genetic studies conducted on a large group of participants showed that the genetic changes can explain only a small fraction of the occurrence of homosexuality [4].

If Not Genes, Then What?
If genes do not explain 100% of homosexuality, there must be some additional factors. Interestingly, a fraction of male homosexuality might be explained by immunology. A phenomenon called the fraternal birth order effect shows that homosexual males have a higher number of older brothers. To put it differently, having a son increases the probability of the next male child being homosexual.
This is explained by the maternal immunity hypothesis. It states that male offspring immunize the mother to male cells, thus producing anti-male antibodies during the next pregnancy with a male. The theory posits that those antibodies cross the placenta and blood-brain barrier, changing the brain’s development. This, in turn, may cause diverted sexual attraction and sexual orientation in the male offspring [5]. This phenomenon is the most thoroughly established factor in the field of human homosexuality [1]. However, we cannot forget that more than half of homosexual males have no older brothers [1].

The Neuroscience of Homosexuality
Concerning the ‘homosexual brain’, a number of brain regions have been shown to be, either functionally or anatomically, different in homosexuals compared to heterosexuals. Research has shown that brain regions such as the interstitial nuclei of the anterior hypothalamus show similar anatomy in homosexual men as in heterosexual women, that is clearly different from heterosexual men [6]. Yet it must be noted that even if homosexual males’ brains are similar to those of heterosexual women, it is not clear whether those changes precede the development of homosexuality, or whether attraction to males has elicited changes in the brain.

Environment and Sexual Orientation
In his paper, John Bancroft argues that homosexuality is caused by environmental factors [1]. He starts with an argument that homosexual males usually experience sexual attraction earlier than heterosexuals. They might therefore develop same-sex attraction because at this point of time, boys spend most of their time with other boys. This is, however, only a speculation.
He goes further and says that homosexuality is often just a phase in human development and that the final phase is heterosexuality. To support his hypothesis, Bancroft gives an example of a people in Papua New Guinea: Young boys around the age of ten are taken to all-male dormitories. They are told to fellate older boys and swallow their semen (in a belief that it is crucial for their proper development). At a particular age, they leave the dormitories and lead a heterosexual life that leads to marriage. He claims that this proves his argument of homosexuality being just a phase. Yet, the author fails to mention that activities performed in all-male dormitories might be merely a cultural concept and that in no way are they a proof of homosexuality.
Additionally, nurture theorists claim to have identified characteristic familial patterns that are supposedly related to children’s homosexuality. Those include low paternal presence or high maternal cues in the case of male homosexuality. However, this can be easily reversed – perhaps those familial patterns were caused by the homosexuality of children [1].

Homosexuality is multifaceted and extremely complicated

Clearly, homosexuality is a multifaceted and extremely complicated phenomenon. But why do we even think about it? The Daily Mail headline from 1993 seems unnecessarily harsh and, at least now, incorrect. We are investigating the basis of homosexuality, but can it have detrimental outcomes? Being able to predict one's sexual preferences might mean denying the right to live. So maybe, we should just let it go and try to accept that people are different no matter where this difference comes from.

[1] Jannini et al, J Sex Med, 2010
[2] Bailey and Pillard, Arch Gen Psychiatry, 1991
[3] Hamer et al, Science, 1993
[4] Mustanski et al, Hum Genet, 2005
[5] Blanchard and Bogaert, Am J Psychiatry, 1996
[6] LeVay, Science, 1991

by Filip Morys, PhD student Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig
This article originally appeared in CNS Volume 7, Issue 3, Nature vs Nurture 

The Origins of Intelligence

The intelligence quotient (IQ) is the best predictor of success in academia and at work. It also serves as a reliable indicator of longevity [1], making the origin of intelligence and the possibility of enhancing it a most interesting research topic.

The theory of multiple intelligences proposed by Howard Wagner in 1983 outlines nine types [2]. Some of them, such as bodily-kinesthetic intelligence (“body smart”) would be hard to assess using a written test. Yet, it has been shown that people who performed well on any single test section, such as linguistic intelligence, also score high on other areas [2].

Source

Big Brains Mean More Intellect
Intelligence positively correlates with the size of the whole brain [1]. However, brain size is limited by skull size and the skull has to pass the birth canal. Complications are hence more likely during the birth of naturally intelligent babies, possibly lowering their survival chances. Moreover, the individual volumes of brain areas are highly heritable [1,3], supporting the theory that nature is more influential on intelligence than nurture. Thus, not surprisingly, in diseases that cause dementia, brain cells are lost and the brain effectively shrinks.

Genes for Smartness and Intellectual Disability
Intelligence is a polygenetic trait. This year, the University of Edinburgh announced the discovery of the first intelligence gene. A highly active NPTN gene allows adolescents to score higher on intelligence tests [4]. The gene codes for a neuronal synapse protein that plays a role in brain development and neuronal signaling. Surprisingly, the NPTN gene explains only about 0.5% of the variability in intelligence. Conversely, candidate gene studies have revealed over 282 genes associated with intellectual deficits (formerly known as mental retardation).

“The measure of intelligence is the ability to change.” – Albert Einstein

Results pooled from a number of studies conducted during the last century on human intelligence research indicate that genetic factors are responsible for up to 50% of differences in intelligence between individuals [1,5].

Race over Education or Education over Race?
The philosophy of race superiority suggests that some ‘types’ of humans are superior from birth because of their lineage. Fortunately, this has largely been unpopular since the abolishment of slavery in America (1865) and the defeat of Nazi Germany (1945). Following each of these events, the Caucasian and Afro-American races began to mingle. With the establishment of racially integrated schools, it became apparent that Afro-Americans showed a lower cognitive ability compared to their white peers [5]. This result was partly attributed to their lower socioeconomic status [5], but may have fueled racism in Europe.

Intelligence is an indicator for success

A post-World War II study in Germany looked at the “occupation babies” of Afro-American and Caucasian American soldiers with German mothers. The IQ of the mixed-race children was 96.5 compared to 97 in Caucasian children [6]. This suggested that inheritance of culture, education, and equal opportunity (rather than race) influence IQ.

Dirty Minds at Age 5 Associated with Lower IQ
A study published this year showed that the exposure of pregnant women to air pollution released by the burning of fossil fuels can cause birth defects and lower the IQ of their offspring by about 3.8 points at age 5 [7]. This result persisted even after the scientists accounted for the level of parental education and several other factors that might influence child IQ. Similar studies have shown that pollution is a cause of birth defects, childhood behavioral disorders, and rare cancers [7].

The Recipe for Raising a Genius Is Continuous Practice
In 1993, K. Anders Ericsson presented evidence showing that violinists who practiced more than 10,000 hours before their 20^th birthday were likely to become professionals [6,8]. This was applied to the mastery of other skills and eventually became known as the 10,000 hours rule. Talent plays a lesser role.
A standard IQ test provides no or unreliable results for half of the intelligence types known so far. Intrapersonal intelligence, for example, contributes to good teamwork, stress management, and leadership. However, there is no comprehensive and standardised measure for it [9].
It requires four hours of practice (with coaching and reinforcement), for six days a week, for fifty weeks a year, over ten years will help you master anything! It's no wonder, really. But honestly, how many of us would volunteer to undergo such rigorous training?

[1] Gardner, The Nine Types of Intelligence, http://bit.ly/19kchVz
[2] Deary et al, Eur J Hum Genet, 2006
[3] Science Daily, 2007, http://bit.ly/1s8kvcf
[4] Desrivières et al, Mol Psychiatry, 2014
[5] Dickens, Future Child, 2005
[6] Blech, Spiegel Online, 2010, bit.ly/1pVTiEV
[7] Perera et al, J Public Health Policy, 2014
[8] Ericsson et al, Psychol Rev, 1993
[9] Arora et al, Med Educ, 2010

by Rick Cornell Hellmann, PhD student AG Schwab
This article originally appeared in CNS Volume 7, Issue 3, Nature vs Nurture 

How Much of Ourselves Are We Born With?

Today is Universal Children's Day, which was established in 1954 to promote international togetherness and awareness among children worldwide. In today's article we are revisiting the nature versus nurture debate.

The phrase ‘nature versus nurture’ is derived from early studies on the effects of parenting on childhood development. Researchers sought to determine the relative contributions of an individual’s innate qualities, determined by one’s genes (nature), and parenting or personal experiences (nurture) on the psychological and behavioral traits of children. If a child shows aggressive behavior, was he or she genetically ‘programmed’ to behave in such a way, or is it the product of his or her upbringing or environment? Consider if one of the child’s parents is also aggressive. Did the child acquire this behavioral trait through exposure to his or her parent's behavior or through inheritance?
No concept is as pervasive in the study of health and disease as distinguishing the effects of internal and external stimuli on bodily function. Since Claude Bernard elegantly introduced the idea, it has not only formed the basis of modern physiology but has also helped us understand numerous pathological states in terms of the interaction between inherited and environmental factors.
Over the years, the controversy has extended beyond childhood behavior to intelligence, sexual preference, and the propensity for certain diseases (see ''The Origin of Intelligence'' and ''Can You Raise Your Kids Gay?''). Despite being heavily researched, at least two problems make the nature versus nature debate a major challenge facing modern biology. The diseases and traits being investigated, particularly those to do with the brain, are themselves complex and often hard to characterize. Moreover, as our understanding of biology progresses, separating the consequences of intrinsic and extrinsic factors on a certain physiological or pathological state becomes increasingly difficult (see here).

Shedding Light on the Issue Using Twin Studies
Separating the effects of genes and environment on childhood development and the pathogenesis of diseases can be achieved by performing adoption and twin studies. Francis Galton first proposed this approach in 1875. It gained impetus at the beginning of the 20^th century when Gregor Mendel’s insights into the mechanism of heredity became widely known. Identifying differences in specific traits by studying monozygotic twins, who share identical genetic information, over portions of their lives gives us insights into the contribution of the environment in developing these characteristics.
In terms of psychological traits, separated twins usually grow up to be very similar even when brought up in substantially different environments. In the landmark Minnesota Twin Study, which began in 1979, researchers studied more than 100 sets of twins or triplets that had been separated in infancy and raised apart from one another. They found that genetics can explain up to 70% of the variability in personality, intelligence, and temperament between the twins [1].

Implications Beyond Medicine
Investigating the relative contributions of innate and acquired factors in human psychology and health can have far-reaching consequences. Not surprisingly, the nature versus nurture debate has also made its way to the courtrooms. Many experts believe that criminality, for example, is a trait that is predominantly inherited. Thus, defense lawyers sometimes argue (with varying degrees of success) that, in certain cases, people accused of committing crimes cannot be held responsible for their actions because they cannot be held accountable for their DNA.
The discovery of rare mutations that strongly predispose to aggression, such as that of the monoamine oxidase type A gene, has helped encourage the acceptance of such legal arguments [2] (see also ''Tracing the Roots of Aggression"). Biologists and physicians often oppose legal battles that attempt to make use of such a defense. They believe that the public often poorly understands the link between genes and behavior, which is a complex issue.

Is the Debate Obsolete?
Over the past few decades, we have made some astounding discoveries regarding how our genetic material is controlled. We now know that DNA is not the rigid, unchanging blueprint of our entire lives that it was once thought to be. Gene expression is a flexible (yet tightly regulated) process that is modulated continuously in health and disease.
Epigenetics (meaning ‘in addition to’ genetics) is the field of biology that deals with the alterations in gene expression that occur in the absence of changes to the DNA sequence. These changes can persist over long periods of time and, perhaps most interestingly, can be inherited from one generation to the other. The signals that trigger epigenetic changes can come from within the organism itself or from the surroundings (see "Lamarck's Last Laugh" on p.4).
The more we learn about epigenetics, the smaller the distinction between nature and nurture becomes. Consider an example. Exposing an individual to stress can alter the expression of proteins involved in the pathogenesis of mood disorders [3]. This altered expression can persist not only throughout the individual’s lifetime, but can also be transmitted to his or her offspring. If one of this individual’s children eventually develops depression, is the contribution of the exposure of the child’s parent to stress inherited or environmental? The simple answer is both. It thus comes as no surprise that, nowadays, many experts consider the debate obsolete.

Although we should not insist on drawing a line where boundaries are becoming less and less clear, making a distinction between the effects of nature and nurture aids our understanding of complex biological processes.

[1] Bouchard TJ Jr et al, Science, 1990
[2] Brunner, Nelen et al, Am J Hum Genet, 1993
[3] Murgatroyd, Nat Neurosci, 2009

by Ahmed Khalil
This article originally appeared in CNS Volume 7, Issue 3, Nature vs Nurture
 

To Do or Not to Do: Prenatal Testing and Its Ethical Issues

A healthy couple is expecting their first child. The woman is 34 years old and is 16 weeks pregnant. Although she carries no major risk factors, she and her partner decide to opt for prenatal testing. The results of the tests show that their baby girl has Turner syndrome. This is a genetic disorder with a missing X chromosome leading to abnormalities such as short stature, dysfunctional gonads, and problems with the kidney, thyroid, and heart. However, a number of these problems can be treated. The question for the couple now is whether they decide to terminate the pregnancy or carry the child to full term. 

 Source: Merge of pixabay  and wikimedia commons 

What is Prenatal Testing?
Prenatal diagnosis refers to tests performed on the unborn fetus with the aim of detecting genetic and chromosomal abnormalities, as well as birth defects. The most common noninvasive procedure is an ultrasound. This procedure can provide a lot of information about gestational age, fetal position, and can detect abnormalities with up to 90% accuracy.

PRENATAL DNA CAN BE OBTAINED DIRECTLY FROM THE WOMAN'S BLOOD

  
Invasive techniques include amniocentesis, chorionic villus sampling, and fetal blood sampling from the umbilical cord. Amniocentesis can usually be performed only after the 14th week of pregnancy and takes at least a few weeks for the results to be obtained. On the other hand, chorionic villus can be done very early on in gestation (9-12 weeks) and takes only 24 hours for the results [1]. However, with such early testing comes a higher risk to the fetus.
Recently, genetic tests have also been developed, making it possible to analyze fetal DNA directly from the pregnant woman’s blood. But the commercialization of this latter group of tests has spurred a huge legal battle.

Genetic Testing: Criticisms and Defenses
The major ethical issue about prenatal testing is that it increases the number of abortions, potentially supporting the tenets of eugenics. Eugenics stems from the Greek words eu, meaning ‘good’, and -genēs, meaning ‘born’. It refers to the practice of improving the genetic quality of the human population [2]. This philosophy advocates the promotion of higher reproduction of people with positive traits (positive eugenics) and the reduced reproduction of people with less-desirable traits (negative eugenics).
The results of a prenatal test provides a couple with a lot of information about their unborn child. Naturally, one can see how this might lead to supporting eugenics. It is certainly wrong to abort a child based on sex, and some countries have even taken legal action to prevent this practice [3]. However, getting valuable information about the health of their child can make a couple more financially and emotionally prepared to receive their child. Some birth defects like spina bifida can be treated immediately after the child is born. Knowing about such conditions in advance can also prepare medical professionals for the birth.
Another problem that can arise with the birth of a child with a disorder can be the quality of relationship between the parents and the child. For example, parents may not be willing to let their child indulge in certain activities leading to a restriction in the child’s freedom. In addition, for late-onset genetic disorders, the issue of societal discrimination from employers and insurance companies is to be taken into account.

OLDER PREGNANT WOMEN ARE ADVISED TO GET TESTED

  
What is often forgotten is that being a carrier for disease-linked genes does not guarantee getting the disease. Often, physical and environmental factors can influence genetic expression to a large extent. But do the benefits of prenatal testing outweigh the consequences of bringing a helpless baby who you know might suffer into this world?

When Should We Test?
Prenatal testing is usually advised for older pregnant women, couples who have a family history of genetic disorders or already have a child with a genetic disorder, and couples concerned about a specific disorder that might occur more frequently in their ethnic group [4]. On the other hand, every couple has the right to opt for prenatal testing as it provides valuable information about their child. While a negative result will certainly ease anxiety, a positive result will drastically change the couples’ lives. In addition, like all scientific tests, they are also not free from false positives and false negatives. In general, it is always recommended to speak to a genetic counselor before opting for a prenatal test.
The question about whether to test remains a personal matter of conscience, and ultimately,  any decision that this couple takes will change their lives forever.

[1] Alfirevic Z et al, The Cochrane Coll, 2009
[2] National Library of Medicine, 2010
[3] Reproductive Health Matters, 2005, http://www.jstor.org/stable/3776292
[4] http://ubeclu.unibe.ch/insel/GENETEST.HTML

by Apoorva Rajiv Madipakkam, PhD Alumni AG Sterzer
This article originally appeared in CNS Volume 7, Issue 3, Nature vs Nurture