Chris Breen responds to comments on his article in our last issue on mental health
It may be unwise to rule out genes playing any role in mental health, but if they do it is likely to be a complex one that is only a small part of the picture.
The social and environmental contribution to mental illness is even more important than for other illnesses. The human mind and disorders of it are deeply shaped by our social environment.
Blaming the genes of those imprisoned on Nauru or Manus, where over half are currently suffering serious mental health conditions, would be both cruel and implausible.
The reference in my original article to “interactions between genes and the environment that predispose some people to dealing better or worse with particular situations” meant no blame attribution.
I was referring to the many environmental factors that can affect the onset of mental illness, for example class, family support, age, physical health, and the experience of oppression like sexism or homophobia. Those driven to mental illness are in no sense “weaker”.
The claim that genetic tendencies to mental health problems have been well established does not stand up on available evidence. Even if it turns out there are genetic “tendencies” for some disorders, this can’t explain why some people who develop mental health issues are fine at some times, but not at others. And it can’t explain the sheer numbers.
Forty five per cent of the Australian population will experience a mental health issue in their lifetime. That can’t all be down to genetics. If it was then you might as well say the problem is having human genes.
Genetics also cannot explain why mental health issues have been rising. One study reports rates today five times that of the 1930s.
There have been claims that genes are responsible for everything from IQ scores, to poverty or gender differences. But these studies ultimately assume that the unequal world we live in is the natural order of things, not something that contributes to these problems.
As one recent paper looking at widespread concerns about the growing lack of reproducibility and indeed false results in some scientific fields put it, “For many current scientific fields, claimed research findings may often be simply accurate measures of the prevailing bias”.1
All the studies Heather provides are meta-analyses. Meta-analysis is highly dependent on selection criteria. It can play a role in science, but is dependent on the quality of the studies it includes. Further the meta-analyses provided all include a number of twin studies. These have a long history of misuse and systematic bias.
One problem is that twins often share the same environment. It is also difficult to find enough identical twins for statistically useful results.2 In regard to suicide, there are only very small numbers of identical twins who commit suicide each year. A twin study looking for a genetic link to suicide is therefore unlikely to produce meaningful results.
As an example one study provided Genetic Epidemiology of Major Depression: Review and Meta-Analysis includes several twin studies. One of those, by Slater and Shields, used just 67 pairs of identical twins. 16 of the twins identified as schizophrenic were labeled “questionable” as to whether they were monozygotic (identical, from the same egg), or dizygotic (non-identical).
A bewildering array of gene regions have been claimed to be associated with mental illness.
Many studies that do report possible genetic associations report only small effects, many have either not been reproduced or are later contradicted, and there is good reason to believe that many are flawed3.
Treatment
Not all mental illness is the same, and different disorders can have different causes. But there is a difference between mental illness and diseases such as heart disease or cancer. Because there is no objective definition for either schizophrenia or depression, these illnesses are based on classifying particular symptoms. Unlike diagnosing cancer or heart problems, evaluating behavior is very subjective.
The drugs for depression (SSRIs) and anti-psychotics for schizophrenia were both discovered accidentally (through observing the effects they had on people). In both cases they are treating symptoms, not underlying causes. There is debate within medicine and psychiatry about whether SSRIs are effective.
Anti-psychotic drugs can reduce particular acute symptoms of schizophrenia at first onset, but they are a blunt instrument. They have serious side-effects, including shrinkage of the brain over time, heart conditions and permanent involuntary muscle movements. Some people have described anti-psychotics as a chemical straight jacket. There is some evidence that schizophrenic patients who come off drugs fare better compared to those who continue with them long term.4
Mental illness needs to be treated, but there is evidence that “chemical imbalance” theories are wrong. Treatments based on these theories are problematic. Attempts at genetic explanations are not leading to better treatments. More resources need to be put into increased social support and addressing social problems.
Notes
1. John P. A. Ioannidis, Why most published research findings are false PLOS Medicine http://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.0020124
2. As an example, the California Twins Autism Study over turned decades of previous autism twin study claims by studying 192 twin pairs, four times as many as any previous study www.ageofautism.com/2011/07/new-autism-twin-study-demolishes-decades-long-belief-in-genetic-causation.html
3. Marcus Munafò and Jonathan Flint, Genetic ‘breakthroughs’ in medicine are often nothing of the sort The Guardian www.theguardian.com/science/2009/nov/06/genetics-medicine-depression-significance
4. Harrow, Jobe and Faull, Do all schizophrenia patients need antipsychotic treatment continuously throughout their lifetime? Psycholocial medicine http://www.ncbi.nlm.nih.gov/pubmed/22340278
