An introduction to Schizophrenia
Schizophrenia is a mental disease, group of psychotic disorders that interfere with thinking and responsiveness. It is a disease of the brain, like Alzheimer’s and Parkinson’s diseases. A person with schizophrenia has deteriorated occupational, interpersonal, and self-supportive abilities. Schizophrenia is known as one of the most disabling and emotionally devastating illness among mankind. But this disease has been misunderstood for so long that it has received relatively little attention and its victims have been undeservingly stigmatized. Schizophrenia is not a split personality, a common idea about what schizophrenia is, but it is a rare and very different disorder usually common among young people.
The word schizophrenia comes from Greek origins “schizein” and “frenos” meaning split mind. (Wikipedia contributors. “Schizophrenia.” Wikipedia, the Free Encyclopedia.)
But schizophrenia does not imply a split minded personality instead it describes a person who believes two different reality at the same time. While a normal person can only be able to believe in one reality, a schizophrenic person can adopt a second reality which can not be understand by a man in mental health.
Introduction to Causes of Schizophrenia
It is considered that there is not just an etiologic reason behind schizophrenia in fact various factors play roles in the development of schizophrenia. Organic factors, genetic factors, endocrine factors, viral and immune factors are some of them. (A-ksuz, Dr. Emine. Azizofreninin erken doneminde hasta ailelerine uygulanan grup eAYitiminin etkinliAYinin deAYerlendirilmesi)
The nearly universal belief is that the main causes of schizophrenia based on environmental and genetic factors. Some psychiatrist considers both genetic and environmental risk factors-and their interaction-to be on an equal footing. Psychiatric genetics has provided some of the strongest evidence that the environment plays a causal role in the expression of psychiatric illness. (Faraone, T.Tsuang and W.Tsuang, Genetics of Mental Disorder.)
While schizophrenia may affect a person in any time, it is somehow more common in those persons who are genetically bent to this disease. The first symptoms mostly occur between the ages 17-21 or 24-30. As Schizophrenia is a common disease among men, the causes of this disease are yet unknown. According to some psychiatrists there are many possible causes exist. Many things such as genetics, environmental triggers or birth defects may affect people to develop schizophrenia.
When schizophrenia researchers talk about environmental factors of schizophrenia, they mean everything other then genetic factors of the disease. The word “environment” here can be considered as their living areas of patients including their houses, neighborhoods, school or working and other socialization places. But environmental factors is a comprehensive issue which contains social, hormonal, nutritional points as well as education, stress, drug use, personal experiences and so on. So, one must think a wide subject when talking about”environmental causes of schizophrenia” which covers every other factors except genetic ones.
A person born in an urban environment has about a 50% higher risk of developing schizophrenia. A child born from a mother who has Rubella has about a 500% increased risk of schizophrenia. (Public Library of Science, 2005.)
One with blood protein incompatibility, maternal influenza infections, or maternal malnutrition (those are all considered as other environmental factors) is closer to develop schizophrenia than other people. If ones’ genetics are susceptible to develop this disease, life stressors such as broken families, leaving home, unsuccessful business life or failed relationships may affect the emergence of schizophrenia as well. Personal struggles, unsatisfying life styles or lack of live hood may also be developing factor in schizophrenia but these are all not a cause but a factor for the disease.
Because of biological reasons, people may be proclivity to disease but it may take years to emergence of schizophrenia. The combination of biological factors with environmental factors such as stress, business life or family life can help disease to emergence more quickly. These are called as the trigger factors. (A-ksuz, Dr. Emine.Azizofreninin erken doneminde hasta ailelerine uygulanan grup eAYitiminin etkinliAYinin deAYerlendirilmesi)
“One might conclude that these numerous absent or inconsistent small effects mean that there is nothing environmental going on. This being the case, one must accept that the findings with respect to clear environmental factors are negative. Having done this, one can then focus on genetic and epigenetic models, and all that these might entail, such as evolutionary perspective. The position is simple: a single environmental cause of large effect is not there.” (Crow, T J. Sexual selection, Machiavellian intelligence, and the origins of psychosis. Lancet.)
As mentioned above, the causes of schizophrenia are yet unknown, but researches about the subject shows that genes play an important role as well as environment on development of schizophrenia. It is considered that if not a real cause of disease at least genetic factors are important to give more clues about disease. Twin studies are helpful to understand genetics of this disease. In addition to twin studies, schizophrenia genetics research has also studies parent-sibling genetics to get more clues about genetic role of the illness.
The family history of schizophrenia depends upon (as mentioned in the genetic factors) the level of interrelatedness of the family member who had schizophrenia and other brain disorders in the family.But many schizophrenics have no schizoid family history at all. Plus, it is thought that some people are closer to develop this illness unknowingly than others though they both have a schizoid family history.
If so finding a cause for schizophrenia is extremely complicated; there are various factors and triggers linked to each other also genetics of illness can be misleading as it is not yet proved. Psychiatrists have to search for many reasons (both environmental and genetic factors) which could be seen behind of the disorder.
An Overview of Heredity and Genetics of Schizophrenia
Studies on the genetics of schizophrenia show that schizophrenia has a genetic composition. While in general population its lifetime prevalence is %1, the risk of schizophrenia is higher in relatives of schizophrenic patients. Third-degree relatives (e.g. cousins) share their %12.5 genes and carry a %2 risk for schizophrenia. Second-degree relatives (e.g. half brothers) share their %25 genes and carry %6 risk for schizophrenia. Many First degree relatives (e.g. siblings, fraternal twins) share their %50 and carry %9 risk for disease. In addition, in identical twins genetic structure is %100 the same and carries %48 risk for schizophrenia.(A-ksuz, Dr.Emine.Azizofreninin erken doneminde hasta ailelerine uygulanan grup eAYitiminin etkinliAYinin deAYerlendirilmesi.)
It is also known that schizophrenia seen more commonly among schizophrenics’ family members. Among general population the risk of developing schizophrenia is only %1 but if one of parents is schizophrenic the risk increases to % 12.If both of the parents are patients of schizophrenia the risk increases to %35 – %45. If one of the distant relations has this disease, the risk of developing schizoid is %2.5.Moreover if a brother/sister is schizophrenic, the risk is %8.(A-ksuz, Dr.Emine.Azizofreninin erken doneminde hasta ailelerine uygulanan grup eAYitiminin etkinliAYinin deAYerlendirilmesi)
The NIMH genetic studies focus on gathering families’ genetic information to better understand what places one family member at risk and conversely, what protects other family members [from becoming susceptible].” Through genotyping, the NIMH has discovered that “at least 60% of the factors that give rise to schizophrenia maybe related to a genetic susceptibility.” Studies have been done on identical twins to show that while genetics may not be the sole cause of schizophrenia, it at least plays a major role in contributing to the overall development of the disorder. For example, you are more likely to develop schizophrenia if a close family member develops the illness themselves (much in the same way of other illnesses such as Type I Diabetes). “A person whose parent has schizophrenia has a ten percent chance of inheriting the condition directly from them.” While genetic susceptibility is a prominent cause of schizophrenia, arguments have been made against this factor as the main cause due to the fact that many people develop the illness while having no prior family history of the illness. (Morgan, Rebecca. “Genetics, Environment, and Dopamine: The Pathway to Schizophrenia .” The Synapse Newsletter)
Genetic Vulnerability Factors and Schizophrenia
The question here to ask is “Can we define schizophrenic factors as genetic and non genetic subtypes ?” It is hard to define some reasons of this mental disorder as genetic and some others as enviromental factors.It is more suitable to define them as due primarily to genetic reasons or due primarily to enviromental reasons.
Up to this time many things are said about causes of shizophrenia. Today’s accepted view is that there are many reasons which causes this mental illness, sometimes only one of them sometimes combination of them leads to this disease.The gene which causes disease is not known yet. Recent studies indicate that multiple genes play role on disease. (A-ksuz, Dr.Emine.Azizofreninin erken doneminde hasta ailelerine uygulanan grup eAYitiminin etkinliAYinin deAYerlendirilmesi)
“A study which began in 1990, investigating about 20% of the genomes in a large group of families with history of schizophrenia in eastern Quebec, has begun to show clear evidences of the association areas of particular chromosomes with schizophrenia. In particular, chromosomes 11q, 3q, 18q, and 6p have been examined, and the results have shown strong evidence for a schizophrenia susceptibility gene in 6p22-p24 and 11q21-22. Finding the specific gene or genes that lead to schizophrenia has large social implications. The discovery of these genes is the first step towards possible gene therapy. Even if gene therapy is not feasible, the study of gene products can lead to a more detailed biochemical and mechanistic understanding of schizophrenia that may also lead to palliation. If it is known which alleles of which genes cause greater susceptibility to schizophrenia, precautions can be taken, as well, to minimize the chances of developing the disease. ” (Maziade, M. ” Psychoses in the Eastern Quebec Population.” American Journal of Medical Genetics)
New Gene Identifications That Provides Clues to Schizophrenia
According to USA newspaper “Proceedings of the National Academy of Science” a gene called SHANK3 which is mutated, seen in schizophrenic cases. Professor Guy Rouleau said” Our research shows that majority cases of schizophrenia are a result of the mutated gene SHANK3.” He adds they believe that some other researches will help them to prove the effects of this mutated gene SHANK3 on disease. (“Azizofrenide gen mutasyonu etkisi.” Online posting. EHA haber ajansA±.)
Another research about new gene identification published in Rutgers University-Linda Brzustowicz. According to what they say, there is link between the gene CAPON and schizophrenia. The gene activities in patients with schizophrenia differ from other people. It is said that schizophrenic’ CAPON gene shaped more shortly than normal people’s. Results support the idea that schizophrenia is connected with CAPON gene that researchers must obtain more information about its shorter version. (“Azizofreni Geni Bulundu ” Online posting. DonuAYum KonaAYA±. )
Schizophrenia and Genetic Counseling
Genetic counseling or counselling (British English) is the process by which patients or relatives, at risk of an inherited disorder, are advised of the consequences and nature of the disorder, the probability of developing or transmitting it, and the options open to them in management and family planning in order to prevent, avoid or ameliorate it. This complex process can be separated into diagnostic (the actual estimation of risk) and supportive aspects. (Wikipedia contributors. “Genetic counseling.” Wikipedia, the Free Encyclopedia)
Genetic counseling is a service that helps individuals and families understand genetic conditions and use scientific information practically. A genetic counselor works with the person or family, explaining relevant conditions and the inheritance patterns. The counselor will work out the approximate chance of individuals or their relatives developing a condition and explain this chance to the individuals. The main purpose of genetic counseling is to explain to families the chance of them developing conditions and to help them understand this, and work out any decisions they need to make. Genetic counseling is provided by trained counselors who have completed a two-year masters degree. Genetic counseling may also be provided by genetic nurses, psychiatrists and other medical professionals. (“Genetic Counseling.” Blog. Genetic Counseling.)
Genetic counseling may have several benefits for these people. One of the main benefits is that genetic counselors are able to explain the causes of schizophrenia and the chances of individuals developing the condition. They will also discuss what this means personally for the individual. People who have schizophrenia in their family, often see a genetic counselor when they are trying to decide whether to have children or not. Genetic counselors can discuss the different factors involved in this decision, helping the client to weigh up the psychosocial, personal and genetic issues. Genetic counselors are non directive and will never tell a client what to do. Genetic counselors will also explain that having a gene known to be associated with schizophrenia does not mean that individual will develop schizophrenia. (“Genetic Counseling.” Blog. Genetic Counseling.)
“Unlike the search for susceptibility genes for schizophrenia, those interested in non genetic risk factors are not able to map the environment systematically. However, research has identified a number of pre- and perinatal candidate risk factors for schizophrenia. These include family history, season of birth, place of birth, obstetric complications, prenatal exposure to viruses and prenatal famine. Other risk factors have been identified that are more proximal to the onset of illness. (e.g. head injury, substance abuse, life events).
When assessing risk factors, it is important to consider the strength of the evidence (consistency, design rigour), the effect size associated with the exposure (odds rations or relative risks), and the population attributed risk (PAR). The PAR is an estimate of how many cases could be prevented if a particular risk factor were eliminated (assuming that the risk factor is causally related to the outcome; Last, 1988). PAR does serve to rank order risk factors in a manner of interest to prevention research. It emphasizes the fact that small risk factors, if widely distributed among the community, may ’cause’ more cases than rarer, but larger, risk factors. It also has to assume that risk factors are true, risk-modifying factors with causal effect.” (Murray, Robin M., et al., eds. The epidemiology of schizophrenia.)