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Genes, Lesions, and Lead – Their Contributions to the Onset of Schizophrenia

Genes, Lesions, and Lead – Their Contributions to the Onset of Schizophrenia

Two recent studies were published concerning the question “is schizophrenia genetic?”  This is a common question, which we have touched on previously on Schiz Life, so it is with much emphasis that we take a deeper look at some of the current research surrounding this specific question.

Genome-Wide Clinical Microarray Testing

Very recently in the Oxford Journal of Human Molecular Genetics, a research paper was published by members of the Centre for Addiction and Mental Health and The Centre for Applied Genomics on the discovery of genetic circumstances that seem to play a large role or even be a causative factor in the onset of schizophrenia.  It turns out that these genetic factors have already been determined to have a causal relationship (as opposed to a correlative relationship) with autism spectrum disorders.  With our current medical skills, this may not provide an immediate cure, but it is progress in isolating the variables that all contribute to the onset of schizophrenia in certain vulnerable individuals.  It helps build the case that specific genes and genetic alterations play a role in many brain and mental disorders.

Chromosomal Lesions

We must be thankful to the Canadian Institutes of Health Research for providing the much appreciated funding for this wonderful study.  The sample population for this study included 459 adults living in Canada and currently diagnosed with schizophrenia.  What the researchers found was that among these schizophrenics, eight percent featured genetic lesions on chromosome 2.  When this 8% number is extrapolated to account for the entirety of suffers, this means that this genetic rarity could be the cause of schizophrenia for one in every 13 patients.

Forward Progress

This study was also a major step forward in efficiency regarding this type of research.  The scientists were able to develop a procedural approach to systematize the work, which will allow a quicker analysis of genes and chromosomes.  The hope is that this will increase the speed of research and the sensitivity, allowing a deeper look into smaller variables and changes in the structure of the chromosomes.  Because schizophrenia is such a complex illness with many contributing factors, finding all of the possible genetic abnormality combinations will then allow researchers to begin focusing on preventative measures to keep these abnormalities from occurring, even if this means interfering with the development of schizophrenia further up the biological path, such as in the way that these genetic anomalies effect brain growth and development.

Gene-Environment Interaction: Chronic Lead Exposure

In another study published in the Schizophrenia Bulletin, mice that were previously engineered to feature a human gene partially responsible for schizophrenia were repetitively exposed to dosages of lead in their early stages of development.  The researchers at Columbia University’s Mailman School of Public Health and the Johns Hopkins University School of Medicine determined that these exposed mice exhibit structural brain changes and behaviors associated with schizophrenia.  The consistency of these changes and behaviors led the researchers to the conclusion that there is a synergy between being predisposed genetically to developing schizophrenia and constant contact with lead.  This synergy arises because the lead seems to instigate the genetic risk factor into becoming no longer a risk, but a causative factor.

Lead Triggers Schizophrenia

It has been long-known that there is a relationship between prenatal exposure to lead in humans and the development of schizophrenia.  However, the question of how lead triggers this illness to develop remained a mystery.  But by mutating mice to carry a human gene known to be involved in schizophrenia, these researchers were able to isolate this pathway.  It turns out that lead inhibits the activity of the N-methyl-D-aspartate receptor in the brain.  With the inhibition of the synapse activity, normal brain development is affected with specific deterioration effects on memory and learning.  This hypoactivity of this specific receptor, in combination with the reduced glutamate neurotransmission are both large explanations for the memory, learning, and other dysfunctions associated with schizophrenia.

The sample population of mice involved two groups, a control group of normal mice and an experimental group of mice given the mutant Disrupted-in-Schizophrenia-1 gene discussed above that makes humans more vulnerable to schizophrenia.  Both groups were split in half, with each sub-group being either fed food with lead or a normal diet.  They were then all four subjected to a battery of brain scanning and behavioral examinations to detect any development of the illness.

Forward Progress

The main take-aways from this study is that the environment does have an effect on the expression of genes, and not just those that are considered risk factors.  It should also be noted that lead is not the only toxic chemical that can effect this specific receptor.  It has paved the way for more research to further isolate variables such as exposure times to these chemicals, including pre-natal and post-natal windows.

Unfortunately, our animal brothers are taking the hit for this one, but their sacrifice will lead to the reduction of suffering for millions of humans.  Progress is being made!

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