Breaking News: The Cause of Schizophrenia Finally Discovered?
On January 27, 2016, a study1 was published online in the prestigious journal Nature that touted the possibility of discovering some potential biological origins of an "illness" called "schizophrenia" (See note at the end). Subsequently, headlines across the world beamed excited proclamations of the latest breakthrough to occur in psychiatric research. Here is just a small sample of what the major media outlets were purporting:
"New study helps explain cause of schizophrenia" - CNN
"Researchers say they're now closer than ever to understanding the science behind schizophrenia" - The New York Times
"Scientists open the 'black box' of schizophrenia with dramatic genetic finding" - The Washington Post
"Genetic study provides first-ever insight into biological origin of schizophrenia" - The Broad Institute of MIT and Harvard
"Schizophrenia breakthrough as genetic study reveals link to brain changes" - The Guardian
Clearly some amazing discoveries must have emerged from this groundbreaking study! The sound bites have certainly led a very large population to come to believe so. The problem is, there is nothing profound about this study at all and, in fact, it is one of the least profound studies to emerge in the last few years on the topic of "schizophrenia". The information that has been disseminated to audiences across the globe, no doubt with the assistance of a rhetorically biased news release and included highlights, is distorted, it asserts exaggerated claims based on reductionistic conclusions, and it ignores the robust support that has accumulated that undermines the genetic disease model of "mental illness" and the categorical understanding of experiences falling under the umbrella term "schizophrenia".
While these news reports discuss the "dramatic" "first-ever insights" and the assumed fact that scientists do not have a clue what causes "schizophrenia", the accumulating evidence indicating an almost irrefutable causal relationship between childhood adversity and most experiences labelled psychotic gets completely disregarded. This is despite the fact that childhood adversity can actually explain the very biological "discoveries" being promoted in the first place. Additionally, many of the biological correlates associated with the category of schizophrenia are also found in persons not diagnosed as such, whether they meet criteria for another disorder or none at all, and are more generally associated with chronic stress and trauma than any discovered disease process. How can this "breakthrough" study go viral across the globe without any consideration of context or the broader literature base explaining the causal pathways of "schizophrenia"? How does this study actually fit in to greater research base?
What are the study findings?
Genetic associations with "schizophrenia"
The authors' premise for conducting the study was an association previously found between variations of the genes of the major histocompatibility complex (MHC) locus and a diagnosis of schizophrenia at the population level. What does this mean in English? It means that there was a very tiny statistical likelihood that variations of genes associated with the immune system were more prevalent in a group of individuals determined to fall into a category called schizophrenia as compared to another group not diagnosed as such. In this particular study, Sekar et al. discovered that, specifically, part of this association was explained by an increased expression of the C4 protein. This particular protein in humans is involved in a process called synaptic pruning. As stated in the New York Times article, an increase in the C4 protein is estimated to be associated with a .25 (one quarter) percent increase in the risk of meeting criteria for a diagnosis of schizophrenia in the general population.
Reduced synapses and synaptic pruning as possible causal mechanisms for schizophrenia
The theory that synaptic pruning may be defective in individuals diagnosed with schizophrenia, and therefore may explain why it tends to emerge in late adolescence, was first purported over 30 years ago by Feinberg2. Synaptic pruning refers to a process that occurs in early childhood (around ages two to four) and again in late adolescence (around the ages of 15 to 18) wherein "excess" neural synapses, or connections, are eliminated in the brain. There is some evidence that individuals who are diagnosed with schizophrenia tend to have reduced neural connections in the brain. The Feinberg hypothesis asserts that this may be explained by a faulty process that occurs during this synaptic pruning in adolescence that is likely genetic in origin.
Due to lack of evidence at that time, this hypothesis was largely ignored, until it was revisited3 10 years later during the "decade of the brain". It was believed that a specific errant process of synaptic pruning may underlie schizophrenia wherein there is an excessive elimination of neural connections, specifically in the prefrontal cortex. This means that there is less activity in the area of the brain associated with decision making, problem-solving, rational thought, and attention. The prefrontal cortex has been shown fairly frequently to have decreased activity and decreased neural connections in individuals experiencing so-called psychotic phenomena.
The Feinberg hypothesis of excessive synaptic pruning emerging from some illness process is still an unproven hypothesis, but is indirectly supported by the evidence demonstrating the deceased connections and activities in the prefrontal cortex of some individuals diagnosed with schizophrenia. The Sekar et al. study was based upon trying to help explain how, if this hypothesis is true, the process might be explained. The study did not prove this hypothesis, nor did it develop the hypothesis; it simply gave some evidence of how this process might be explained at a biological level if it is, in actuality, true. The study also did not "help explain [the] cause of schizophrenia", as purported by CNN; it simply provided some possible evidence of a biological correlate that exists in a small number of individuals diagnosed with schizophrenia that may underlie a hypothesized process that may exist in some individuals diagnosed with schizophrenia. This is breaking "dramatic" news?
The bigger picture
Taken at face value, if there is, in fact, a greater number of C4 protein and variations of the genes in the MHC locus in some individuals diagnosed with schizophrenia than in the general population, and this explains a hypothesized excessive pruning process that occurs in adolescence, then what might really be going on? Remember, this study (and most others like it) have found a biological correlate associated with a small number of individuals fitting into a particular category called schizophrenia. This does not necessarily mean that there is a causal relationship or that an actual illness process is occurring. As I write this, my brain is demonstrating many biological correlates in activity, including an increased stress response. As you read this, your brain is demonstrating a very different biological correlate that may or may not also have an associated stress response. Just because there is a difference in brain biology, and just because there is an associated stress response, this does not mean that an illness is in place, nor does it prove that either of us is "mentally ill".
Looking at the broader scientific literature, it is clear that there are certain biological correlates associated with a diagnosis of schizophrenia at the group level. But, this does not tell us much of anything beyond the fact that the brain and body are demonstrating a different physiology than those who are not in such extreme distress. This is to be expected. However, these associations are also evident in other major DSM-defined diagnostic categories, including posttraumatic stress disorder. Most problems that get labelled as mental illness emerge in adolescence as well, and synaptic pruning has been suggested as one major reason for this across diagnostic categories6. In other words, what we seem to be looking at are physiological and neurological responses to difficult life experiences that are correlated with varying manifestations of distress, emotional pain, and socially unacceptable behaviors.
How does all of this relate to the Sekar et al. study?
The immune system
The immune system, inflammation, and schizophrenia
Recall that the genetic variations found in this study, and previous studies, to be minutely associated with schizophrenia are those genes that are also associated with the immune system. C4 proteins, those found to be increased for those with "schizophrenia" in the Sekar et al. study, work within the immune system, in part, by responding with inflammation in order to protect the body. In general, when the immune system responds to a perceived injury or infection, inflammation is the result. Abnormalities in C4 are associated with various autoimmune diseases, such as lupus, kidney diseases, and even alcoholic liver disease (they did not, as far as I can tell, account for the potential confound of alcoholism, by the way).
Interestingly, an unbalanced immune response and a slight inflammatory process of the central nervous system have been associated with individuals diagnosed with schizophrenia4. Because of the discovery of a higher than normal immune cell activity in the brains of those diagnosed with, or considered at risk of, schizophrenia, it has been suggested that early anti-inflammatory treatments might prove an invaluable treatment intervention5. So, the idea that the immune system may be faulty in some individuals diagnosed with schizophrenia is not surprising. Nor is it surprising that genes associated with immune system may demonstrate some variation in individuals diagnosed with schizophrenia. However, this does not mean that C4 abnormalities or inflammatory responses cause some disease called schizophrenia. It may be that some individuals experiencing a psychotic reaction are suffering the direct results of an autoimmune reaction targeting the neuronal structure of the brain. This is the case with encephalitis. Of course, we call this disease of inflammation in the brain encephalitis not schizophrenia. It is understood that they are at least two entirely different problems.
It is also entirely possible (and not even considered in these studies) that behaviors and experiences associated with the diagnosis of schizophrenia are interconnected with an immune response that are all, or partially, resulting from some other source. In fact, the increased response of the C4 genetic proteins and other variations found may be entirely the result of emotional breakdown rather than the cause. Genes are not determinants of most human behavior or experience. Genes are affected by the environment and may get "turned on" by events within the environment, such as pollution, viruses, psychological trauma, and other acquired experiences. The statement by Sekar et al. that "schizophrenia is a heritable brain illness" is a rhetorical declaration that has not been proven, and there are numerous refutations of the research upon which such assertions have been made7, 8. This is an important point to make because genetic variation does NOT equate with genetic (or inherited) disease. And, brain differences do NOT equate with brain disease. Genetic and brain variations can easily arise from environmental events; first, however, one needs to set aside the assumption that "schizophrenia" is a genetic disease and examine the evidence as a whole.
The immune system, trauma, and autoimmune problems
When the immune system becomes faulty, especially over time, tissue damage may ensue. Autoimmune diseases, such as rheumatoid arthritis, are actually inflammatory disorders that occur when an organ, tissue, or internal system is damaged by the immune response. C-reactive protein (CRP) is a biomarker of inflammation that is also involved in the regulation of the complement system9, which includes the C4 protein measured by Sekar et al. In 2007, Danese et al.10 published a study demonstrating that childhood adversity is associated with increased CRP levels in adults 20 years after the experience of trauma. In fact, childhood trauma has been found to be independently associated with autoimmune diseases (including rheumatoid arthritis11 and chronic fatigue syndrome12) later in life, in part through the process of inflammatory and neuroendocrine responses.
There may be some value in considering the Sekar et al. findings in terms of some forms of psychosis being the result of an autoimmune disorder resulting from childhood trauma. The relationships of childhood adversity and "schizophrenia", and the problems in ignoring this relationship, will be discussed shortly, but the point to be made here is that no such possibilities were raised. Rather, there was some discussion about "schizophrenia" being an autoimmune disorder caused by a genetic abnormality, despite the fact that not ALL people diagnosed with this disorder demonstrate an inflammatory response, not ALL demonstrate predictable physiological differences of any kind, and that genetics (or more correctly, epigenetics) may simply be a mediating factor wherein something in the environment (i.e., childhood adversity) may actually be the cause.
Synaptic pruning, as stated previously, is a normal process that occurs in all humans during two different periods of life: early childhood and adolescence. There is large variation in the amount of pruning that occurs, particularly across genders6. The process basically consists of eliminating connections in the brain that are redundant or unused. So, if one is isolated, depressed, and uncared for, areas of the brain associated with empathy, socialization, and executive functioning are likely to be eliminated. Although surely there is some function of genetic determinism in the selection of synapses to eliminate, this is not proven and the environment and one's lifestyle appear to be much more prudent factors in this regard.
The Feinberg hypothesis, which is the basis upon which the Sekar et al. study and their conclusions are based, purports that "schizophrenia" results from an excess of synaptic pruning in the prefrontal cortex. Yet, it has been found that stress and trauma, especially when experienced during adolescence, can result in decreased synaptic density in the prefrontal cortex and these changes can endure into adulthood13. In other words, one cannot differentiate if decreased synapses in the prefrontal cortex are the result of trauma and childhood adversity or if they are the result of some theoretical disease process called "schizophrenia".
Trauma and Psychosis
Recently, another study was published regarding "schizophrenia" that did not go viral through the media, but, some (i.e., me) might argue, should have. Anjnakina et al.14 built on several other recent studies to demonstrate specificity of childhood adversity and psychotic experiences as an adult. A robust association was found between childhood adversity, most notably childhood sexual abuse, and delusions and hallucinations. In a previous study, Bentall et al.15 found that bullying had a specific relationship with paranoia. Perhaps most importantly to the Sekar et al. study is the finding that being taken into custody (i.e., foster care, juvenile justice) as a child was associated directly and robustly with an "excited" dimension of psychosis, characterized by hostility, lack of impulse control and uncooperativeness. This builds on previous research demonstrating that children who experience abuse that comes to the attention of social services are more likely to behave in antisocial and impulsive ways16. These traits are often associated with decreased activity in the prefrontal cortex.
In a very different tone than that of "schizophrenia is a destructive, inherited brain disease", Anjnakina et al. state at the top of their article "The relationship between childhood adversity and psychotic disorder is well documented". Indeed, this is true. There is not enough room here to begin to do the vast amount of literature justice, but I will provide just a few key resources. Read et al.17 concluded in 2005 that child abuse is a causal factor in "schizophrenia". Read et al.18, after identifying similarities in the brains of traumatized children and adults who were diagnosed with schizophrenia, demonstrated the neurodevelopmental pathways through which childhood adversity may cause psychosis. In 2004, Janssen et al.19 established a strong dose-response relationship between childhood abuse and psychosis after following 4045 individuals from the general population for two years. Bentall et al.15 also found a dose-response relationship between childhood abuse and psychosis (meaning that the greater number of adverse experiences and/or the higher the severity, the greater the risk), wherein those who had a high-severity of childhood abuse were 48.4 times more likely to develop psychosis as an adult. When specificity and dose-response relationships are demonstrated, a causal relationship is strongly probable. In fact, Bentall et al.15 stated that "experiencing multiple childhood traumas appears to give approximately the same risk of developing psychosis as smoking does for developing lung cancer". And, lastly, in the same month as the Sekar study was released (January 2016), so to was a nationwide cohort study out of Denmark and Sweden20 which found that experiencing the death of a first-degree relative before 18 years of age, especially from suicide or accident, resulted in a 39% increased risk of schizophrenia.
Yet, the media screams from the proverbial rooftops the "dramatic" findings that a genetic variant has shown there to be an estimated increase of .25% in the risk of "schizophrenia"? How does this happen? I can surmise many reasons, including corporate and guild interests and financial resources, but at the end of the day no one likes to hear about the bad things that exist in the world. Sadly, as a result, those who are unfortunate enough to live with oppression, social isolation, poverty, institutionalization, and/or child abuse find that when they turn for help, their traumatic experiences are rendered meaningless, their response to the trauma is reduced to a "brain disease" that was probably risen from some defective genes in the first place, and "help" consists of further traumatization and isolation and promises of a better life through a pill. This is, at this point, unjustifiable.
To sum up
It may seem after reading this that the Sekar et al. study has, indeed, given us some useful findings in understanding the pathophysiological mechanisms behind the psychotic experience for some people. This would be correct as far as academic gratification is concerned. Inflammation is at the root of most modern diseases, and dietary changes, exercise, and psychotherapy have proven invaluable in treating such conditions. It is a positive step forward to consider the healing effects of anti-inflammatory changes in diet and lifestyle.
The conclusions and recommended possible clinical responses suggested by Sekar et al, however, are dangerously reminiscent of some Orwellian terror. Shall we really entertain the idea that it might be useful to mess around with the brain as it develops and changes over time through invasive chemical or other biological interventions? Does anybody have a clue what Frankenstein result may come out of such actions? Are we supposed to start genetically manipulating people because of a barely noticeable increased risk of a category of disease that is not even valid or reliable in the first place? There is a strong association of "mental illness" and creativity; are we to rid the world of innovation and creation? This may reek of hyperbole, but if there is even a small chance of such outcomes is it worth it? Have we not learned from previous experience that just because those in power say something is so, or even that it is helpful, that this means it's true?
We keep hearing about how wonderful modern Western mental healthcare is…if that were the case why did the World Health Organization find that countries who did not adopt our paradigm of "care" (i.e., "undeveloped" countries) had better outcomes21, 22 only to find that 30 years later, after adoption of that very paradigm, outcomes are no better than they are here? If our treatment paradigm was so "advanced", then why have disability rates and rates of illness continued to climb year after year, even as non-mental illnesses have decreased?23
What if, instead, we tried to decrease poverty, inequality, racism, and child abuse? What if that? What if we paid heed to more humane interventions that allow for the variety of human experience (for instance, the Hearing Voices Network, Soteria, Open Dialogue, etc. ) and helped people to feel less isolated, more secure, and empowered to find meaning in life, as those who have personal experience with such experiences have asked for? What if we listened to those who have been there instead of telling them what they should or should not find helpful? What if we considered the whole person instead of reducing them to cells in a brain? These would be silly suggestions for someone facing a genetic brain disease. But, for someone experiencing the natural result of overwhelming life experiences, perhaps they are not. Will the media pay attention to this before it's too late?
Note: The category of "schizophrenia" has been determined to lack validity and reliability as a diagnostic category and does not have any predictive value, and this is agreed upon even by the most preeminent experts in mental health research. In order to argue the points as they have been put forth in the media, and as they exist in the research, this subject was not argued here for purposes of brevity.
- Sekar, A., Bialas, A. R., de Rivera, H., Davis, A., Hammond, T. R., Kamitaki, N.,…& McCarroll, S. A. (2016). Schizophrenia risk from complex variation of complement component 4. Nature. doi:10.1038/nature16549
- Feinberg, I. (1983). Schizophrenia: Caused by a fault in programmed synaptic elimination during adolescence? Journal of Psychiatric Research, 17(4), 319-334.
- Keshavan, M. S., Anderson, S., Pettergrew, J. W. (1994). Is schizophrenia due to excessive synaptic pruning in the prefrontal cortex? The Feinberg hypothesis revisited. Journal of Psychiatric Research, 28(3), 239-265.
- Muller, N., Myint, A. M., Schwarz, M. J. (2012). Inflammation in schizophrenia. Advances in Protein Chemistry and Structural Biology, 88, 49-68.
- Bloomfield, P. S., Selvaraj, S., Veronese, M., Rizzo, G., Bertoldo, A., Owen, D. R.,…& Howes, O. D. (2015). Microglial activity in people at ultra high risk of psychosis and in schizophrenia: An [11C]PBR28 PET brain imaging study. The American Journal of Psychiatry, 173(1), 44-52.
- Paus, T., Keshavan, M., Giedd, J. N. (2008). Why do many psychiatric disorders emerge during adolescence? Nature Reviews: Neuroscience, 9, 947-957.
- Joseph, J. (2015). The trouble with twin studies: A reassessment of twin research in the social and behavioral sciences. New York: Routledge.
- Ross, C. A., & Pam, A. (1995). Pseudoscience in biological psychiatry: Blaming the body. New York: John Wiley & Sons.
- Pepys, M. B., & Hirschfield, G. M. (2003). C-reactive protein: A critical update. Journal of Clinical Investigation,111, 1805-1812.
- Danese, A., Pariante, C. M., Caspie, A., Taylor, A., & Poulton, R. (2007). Childhood maltreatment predicts adult inflammation in a life-course study. Proceedings of the National Academy of Sciences, 104, 1319-1324.
- Dube, S. R., Fairweather, D., Pearson, W. S., Felitti, V. J., Anda, R. F., & Croft, J. B. (2009). Cumulative childhood stress and autoimmune diseases in adults. Psychosomatic Medicine, 71(2), 243-250.
- Heim, C., Nater, U. M., Maloney, E., Boneva R., Jones, J. F., & Reeves, W. C. (2009). Childhood trauma and risk for chronic fatigue syndrome. Archives of General Psychiatry, 66(1), 72-80.
- Leussis, M. P., Lawson, K., Stone, K., & Andersen, S. L. (2007). The enduring effects of an adolescent social stressor on synaptic density, Part II: Poststress reversal of synaptic loss in the cortex by Adinazolam and MK-801. Synapse, 62, 185-192.
- Ajnakina, O., Trotta, A., Oakley-Hannibal, E., Di Forti, M., Stilo, S. A., Kolliakou, A.,…& Pariante, C. (2016). Impact of childhood adversities on specific symptom dimensions in first-episode psychosis. Psychological Medicine, 46(2), 317-326.
- Bentall, R., Wickham, S., Shevlin, M., & Varese, F. (2012). Do specific early-life adversities lead to specific symptoms of psychosis? A study. Schizophrenia Bulletin, 38, 734-740.
- Cohen, P., Brown, J., & Smaile, E. (2001). Child abuse and neglect and the development of mental disorders in the general population. Development and Psychopathology, 13, 981-999.
- Read, J., van Os, J., Morrison, A. P., & Ross, C. A. (2005). Childhood trauma, psychosis, and schizophrenia: A literature review with theoretical and clinical implications. Acta Psychiatrica Scandinavica, 112, 330-350.
- Read, J., Fosse, R., Moskowitz, A., & Perry, B. (2014). The traumagenic neurodevelopmental model of psychosis revisited. Neuropsychiatry, 4(1), 65-79.
- Janssen, I., Krabbendam, L., Bak, M., Hanssen, M., Vollebergh, W., de Graaf, R., & van Os, J. (2004). Childhood abuse as a risk factor for psychotic experiences. Acta Psychiatrica Scandinavica, 109, 38-45.
- Liang, H., Olsen, J., Yuan, W., Cnattingus, S., Vestergaard, M., Obel, C., Gissler, M., & Li, J. (2016). Early life bereavement and schizophrenia: A nationwide cohort study in Denmark and Sweden. Medicine, 3. Doi: 10.1097/MD. 0000000000002434.
- de Girolamo, G. (1996). WHO studies on schizophrenia. The Psychotherapy Patient, 9, 213-231.
- Jablensky, A., & Sartorius, N. (2008). What did the WHO studies really find? Schizophrenia Bulletin, 34(2), 253-255.
- Viola, S., & Moncrieff, J. (2016). Claims for sickness and disability benefits owing to mental disorders in the UK: Trends from 1995 to 2014. BJPsych Open, 2, 18-24. Doi: 10.1192/bjpo.bp.115.002246.