Is Schizophrenia Caused by Environmental Factors or Genetic Factors?

Abstract

Schizophrenia affects a quarter of a million people in the UK. Schizophrenia is a psychotic disorder which unmediated patients find difficulties to sustain relationships and can become unable to represent themselves appropriately, this can lead to difficulties with employment, cause hallucinations, delusions, loss of sense of pleasure, loss of concentration, unnecessary behaviour outside of the social norm and social withdrawal. This essay highlights the environmental factors and genetic factors which can influence the role of an individual developing schizophrenia, the symptoms, how schizophrenia is diagnosed and the treatment in controlling the illness.

Studies however, are difficult to replicate and greater work needs to be complete in all areas of the development of schizophrenia. Inheritance is important in schizophrenia although it is not 100 percent based on the genetic of the individual. Dizygotic twins have a 17 percent risk factor to developing schizophrenia whereas monozygotic twins have a staggering 48percentrisk of developing the disease. There has been 27 genes which have been identified with schizophrenia to date although interestingly dopamine was not among them although the dopamine receptor is.

Drugs and psychiatric therapies have been found effective in some cases although the drugs do have a few side effects and the talking therapies cannot be guaranteed to always work. Environmental factors can also be important with the treatment and family members need to support individuals correctly.

Schizophrenia is a major illness within the UK. Current statistics have shown that a staggering 220,000 people, both male and female, are being treated for the illness by the NHS according to (living with schizophrenia, 2017). Schizophrenia has been found to have no definite answer in the causes of the illness but several different factors which combine to create the illness. Schizophrenia can be an important issue to cover due to the staggering amount of individuals being treated in the UK each year. But what are the causes of the illness and how can it affect daily lives of the individuals who suffer from it. This essay will analyse what factors can influence an individuals likelihood of developing the disorder, the symptoms associated with the disorder and what treatments are available to ensure individuals with the disorder can live a happy and normal life.

Bressert (2018) suggests that symptoms regarding schizophrenia are both psychological and physical leading from delusions, hallucinations, catatonic behaviour and disorganised speech, Silber (2014) also back up these symptoms. Doctors describes there being two types of symptoms in individuals who suffer with schizophrenia, positive symptoms and negative symptoms.

Tracy (2016) along with Silber (2014) states that positive symptoms refer to excess or distortion of normal functions. Positive symptoms are most commonly associated with schizophrenia due to the individuals confusion and beliefs of reality. Dr Knott (2016) states that a primary symptom of schizophrenia would be delusions and hallucinations. Knott explains delusions as a false belief which is ongoing and based on incorrect reasoning. He argues that there are criteria which are required for a delusion. One being the certainty of a situation, this meaning that the individual believes the delusion unconditionally. Secondly, incorrigibility leading to the belief not being diminished in any way. Thirdly, impossibility which is positively fabricated. In an individual with schizophrenia delusions will be classified as primary, this means that it will occur within the mind and will be fully formed with no proceedings and will be showing a range of delusional topics, polythematic. Hallucinations are described as a sensory perception being experienced regardless of there being no external stimulus. Hallucinations can range from being visual, auditory, olfactory or tactile. Visual hallucinations have been reported in 72% of patients with schizophrenia although auditory characteristics are seen in most patients which relates to one or more taking voices.

Other positives symptoms of schizophrenia will also include movement disorder, where individual becomes agitated or catatonia. Disorganised behaviour, showing signs of unusual and inappropriate behaviour which could be childlike. Another would be thought disorder, difficulty organising or expressing thoughts resulting in patients stopping mid-sentence, making up words or speaking of nonsense.

Whereas negative in schizophrenia will be a decrease or the absence of normal day to day functions. These may exist many years before positive symptoms occur in schizophrenia due to negative symptoms being much harder to diagnose. Negative symptoms in schizophrenia include apparent lack of emotion (small emotional range), neglect of personal hygiene, loss of motivation, decreased ability to complete activities and neglect social interaction. Individuals suffering from negative symptoms are more prone to require help with everyday tasks including taking care of themselves. Due to the negative symptoms an individual may show traits of not wanting help or that they are frustrated and not trying while this is just an exhibition of the symptoms.

Moving on, NHS UK (2016) suggests that there is no sole test for diagnosing schizophrenia and it is typically diagnosed after crucial assessments undergone by a specialist within the mental health field. It states that individuals who may sense a change in their mood or behaviour to seek help from their doctor. During an appointment with the doctor, if schizophrenia is suspected the individual will be referred promptly to the local community mental health team (CMHT). The CMHT consists of different professionals to support individuals with complex conditions. Usually a psychiatric will carry out a more thorough assessment of the symptoms. Alternatively, due to their delusional thoughts, individuals showing signs of schizophrenia may believe that there is nothing wrong with them and refuse help. At this stage of diagnoses a mental health professional will undertake a diagnostic checklist. Usually if the individual has experienced one or more of the above symptoms for most of the time of a month, symptoms has shown significant impact on performance in work or studies and that all alternative illnesses has been ruled out such as alcohol intake drug misuse and other possible disorders a positive diagnosis of schizophrenia could be expected.

Grohol (2019) explains that schizophrenia will require lifelong treatment due to the illness being a chronic condition which exist in on a wide spectrum. He states that although schizophrenia can be devastating and sever that there are treatments which have been found to be effective. Medication can help with controlling symptoms such as psychosis and is the main treatment for schizophrenia along with psychotherapy including cognitive behavioural therapy, arts therapies and family interventions which is done alone side a professional within this field of treatment.

There are two classes of medications used in the treatment of schizophrenia, one being antipsychotics. This medication has been found to block dopamine receptors in the body and are effective in controlling the hallucinations, delusions and confusions which has been caused by the illness. Antipsychotics such as chlorpromazine, haloperidol and fluphenazine have all been a manageable medication used. Another being atypical antipsychotics, these include quetiapine, risperidone and olanzapine. This medication was first introduced in the 1990 and have been found in some cases to have a positive effect on both positive and also negative symptoms of schizophrenia.

Mind (2017) recommends cognitive behavioural therapy to be used alongside medication to help the individual cope with symptoms of psychosis, to reduce stress, handle other problems that could arias due to the condition and also manage side effects caused from medication. Cognitive behavioural therapy is a treated as a talking therapy for patients and helps to ease the individuals patterns of thinking or behaviour. This type of treatment will focus of helping the individuals cope with symptoms of schizophrenia instead of convincing the individual that their experiences and beliefs are incorrect. Family interventions can help relative or carers find a way which is best suited to support the needs of the patient and support families in finding necessary ways of coping and solving problems together. Family intervention is a type of treatment regarding relatives, carers and families of the patient who is diagnosed with schizophrenia. All treatments go hand in hand and together can help the individual diagnosed with the condition in finding a way to get their lives as close to normal as possible (Tse, 2013).

Moving on to different causes of schizophrenia. According to Silber (2014) there have been numerous evidence and studies found to have shown the different causes of schizophrenia, although no one cause has been constructed. Mind (2017) suggests that schizophrenia has been generally agreed to have a combination of causes rather than one. Environmental factors and genetic factors have a strong link within the cause of schizophrenia.

According to Schoenstadt (2017) genetic factors are not the exact cause of schizophrenia although genes do have a reflection on a person’s risk of developing the condition. Schoenstadt suggests that schizophrenia will occur in only 1% of the general population despite the fact schizophrenia is also seen in 10% of people who has a parent of biological sibling who suffers from schizophrenia. Twin studies have also been produced to potentially helping identify the genes responsible for the symptoms of schizophrenia.

Scientists from the University of Copenhagen in Denmark collectively gathered information through their Danish Twin Register and collaborated that information with the data collected from the Danish Psychiatric Central Research Register. This research found that a staggering sample of 31,524 twins born between 1951 and 2000 had realistically required psychiatric support. Due to monozygotic twins inheriting the same sets of genes from the parents it is possible to compare them with those of dizygotic twin pairs and can provide a powerful indication whether schizophrenia was caused by the genes a person inherits or as a result of environmental factors.

However, John (2014) states that research into the neurodevelopment of schizophrenia has also been undergone by an international collaborative group of researchers, studying the brain development during childhood and adolescence in people with and without schizophrenia. The researchers have now been able to describe brain development outlines to supplement the development of schizophrenia. This has been able due to the new statistical approaches and long term follow up with individuals. Research investigating the path of cortical thickness growth curves was conducted on 106 individuals with childhood onset schizophrenia and a comparison group of 102healthy individuals. Each individual ranging for ages 7-32 had repetitive imaging scans over the course of a number of years. Using above 80,000 vertices through the cortex, the research were able to fashion the effect of schizophrenia on the growth curve of the cortical cortex. This research discovered transformations which occur with a specific group of vastly connected brain regions which mature in association during distinctive development, although, follow changed trajectories of growth within schizophrenia. These finding show a relationship that the theorem that schizophrenia is a neurodevelopmental illness and the hypothesis that schizophrenia is a disease of altered connectivity amongst different sections of the brain.

Scientist have also found that individuals who have the disorder may well be more likely to have glitches within their genes which could contribute to disruptive brain development. Studies show that certain chemicals of the brain can control thinking, emotions and behaviour can be too active or not active enough within individuals with schizophrenia. They believe that brain loses tissue over time which PET scans and MRI scans for instance have shown individuals with schizophrenia have shown less gay matter which is the area of the brain which contains nerve cells.

Two chemicals within the brain dopamine and glutamate carry messages to cells along brain pathways, this is where professionals believe can control thinking, motivation and perception. Dopamine is well researched due to it linked characteristics to addiction, psychiatric and movement disorders. Dopamine in individuals with schizophrenia has been linked closely to hallucinations and delusions, this is due to the areas of the brain which drive off dopamine may well become overactive.

Karlsgodt (2014) Claims there are many theories have also justifies schizophrenia being a disorder of reduced or disturbed neural connectivity which impaired communication between brain areas leads to associated symptoms and cognitive changes in individuals with schizophrenia. White matter changes has also been connected to schizophrenia. Supporting evidence of this includes the neuroimaging studies of the first-episode and chronic patients that find white matter volume reductions and structural abnormalities (Write et al, 2000).

There have also been research produced in finding variations in many genes which are likely to contribute to the risk of developing schizophrenia. In a high number of cases multiple genetic changes along with a small effect combine to increase an individuals risk of developing schizophrenia. Although genetic changes are still an active field of research scientists are convinced genes have a higher risk factor leading to schizophrenia that environmental factors alone. Genetics Home Reference (2018) states that deletions and duplications of genetic material in any numerous chromosomes, which have the strength to affect multiple genes, are also known to increase an individuals risk of developing schizophrenia. A small deletion (microdeletion) in an area of chromosome 22 known as 22q11 may be involved within a small percentage of schizophrenia cases. Individuals who show this deletion have also shown other features in addition to schizophrenia for instance heart abnormalities, opening in the roof of the mouth (cleft palate) and problems with immune system and are diagnosed with an illness called 22q11.2 deletion syndrome.

Sekar (2016) explains that researchers feel they have found a new schizophrenia risk factor within genetics. A gene called C4 appears to be involved in the elimination of the connections of the neurons, this is a process called synaptic pruning and occurs naturally in the teen years. Researchers speculate that it is possible that excessive or inappropriate pruning of the neural connections could lead to schizophrenia being developed, which is why schizophrenia symptoms often start or appear during the teen years. This hypothesis was also confirmed during the rodent model (Sekar, A. et al. 2016.) Crew (2016) agrees with this statement and continues to say that in 2014 a tat of researchers from Harvard Medical School performed a genetic study based on 36,989 schizophrenia cases and 113,075 controls. They identified 108 regions of DNA where genetic variants increased an individuals risk of schizophrenia. They continued with their research and combined data from a genetic analysis of approximately 100,000 DNA samples from 30 countries, post-mortem brain samples from 700 patients and animal models. This was created to identify one gene which is associated with the highest risk of developing schizophrenia. Researchers then found the compliment component 4 gene known as C4. This specific gene is associated with the immune system and the development if the brain which also varies is structure significantly across individuals. A genetic investigation of more than65, 000 individuals with and without schizophrenia found that those who carried the specific variant of the gene had a greater risk of schizophrenia in their youth.

Harrison (2019) suggests that if a sibling or one parent has schizophrenia then the chances of an individual developing the disorder is around 10%, if an identical twin has the illness the chances are 50%, although, if both parents suffer with schizophrenia then an individual has 35% chance of developing it themselves.

Environmental Factors have also been studied to analyse the effects on the development of schizophrenia. Environment risk factors include obstetric complications such as prenatal infections, prenatal maternal malnutrition, foetal hypoxia, maternal life stressors birth season and location.  There have also been links found with later candidate environmental factors which can consist of psychological stress factors, substance abuse and individuals personality trait that can contribute to the causes of schizophrenia.

Kraepelin, a leading researcher into schizophrenia suggested that following the 1918 influenza epidemic there were increased numbers of “dementia praecox” now known as schizophrenia, this has since lead Kraepelin to the belief that such infection may be a factor in the development of schizophrenia. Recently, an increasing number of researchers have documented that an infectious hypothesis for schizophrenia is both biological plausible and testable. Investigators from various areas of research such as infectious disease, paediatrics, neonatology, obstetrics and paediatrics have known for some time that infections during prenatal life have many neuropsychiatric development, including behavioural issues, mental retardation, mood alterations and learning disabilities. Additional evidence to this hypothesis was the well replicated excess of births of schizophrenic individuals during the winter and mid spring. This was an era distinct by the increase in the occurrence of infections such as the influenza virus (brown, 2008, p. 7-10).

Substance exploitation has also been found to have been a co-occurring issue among those diagnosed with schizophrenia. In the region of 50 percent of individuals suffering with schizophrenia struggle with drug abuse. Though Substance abuse does not cause schizophrenia it will act as an environmental trigger. Using substances such as amphetamines, marijuana and cocaine can increase the symptoms associated with schizophrenia dramatically and can also cause symptoms to worsen in severity over time. Some researchers believe that individuals who are more at risk of developing schizophrenia are also more at risk for substance use. There is also evidence which shows that environmental factors can also play a role due to most individuals with schizophrenia and substance abuse also experiencing significant trauma early on in life.

Nutritional factors have also clearly been hypothesised to play a role in the cause of schizophrenia. A lack of specific micronutrients and the general nutritional deprivation have both been previously concerned as risk factors of the development of schizophrenia. In one landmark study of prenatal nutritional deprivation known as the Dutch Famine Study (Susser et al 1998), neurodevelopmental conclusions were measured after severe intake of calories where decreased. The rates of schizophrenia doubled for individuals who were conceived under circumstances of nutrient deprivation throughout premature foetal development, whereas, late gestational exposure did not. Later studies lengthened theses finding to schizophrenia showed a 2 fold growth in risk for early gestational exposure to famine (Hoek et al. 1998). Two further studies found evidence that low maternal body mass index or low birth weight can also be associated with schizophrenia (Done et at. 1991: Wahlbeck et al 2001).

Stress also has a partial influence to the glutamate and dopamine which provides with an environmental factor toward schizophrenia and appears to control neurotransmitter function. Furthermore, dopamine dysregulation may also ascend through a process called sensitisation. Varied individuals can be particularly sensitive to the effects of certain drugs for either genetic factors or due to a result of pre-environmental damage. Leading to the reason stress, such as drug use in adolescence may propel the neurodevelopmental impaired individual over the limit for schizophrenia (Picker, 2005).

In conclusion to this essay it can be seen that the genetic factors of schizophrenia has a greater relationship to the individuals chances of developing the illness, it has received further research than the contrasting environmental factors, and have shown that various genetic mechanisms of schizophrenia are only recently being identified. As evidence suggests that genetic vulnerability along with environmental factors can be combined in the development of schizophrenia although without the genetic factors already in place it is of a low certainty the schizophrenia will develop in the individual.

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