Causal Factors of Schizophrenia

Schizophrenia has long been a focus of research due to the seriousness of the disorder as well as the many years of anguish and incapacitation experienced by the patients. Predisposition to schizophrenia is high if an immediate family member has the disorder, but there are chances of developing Schizophrenia even without a family history of the disorder.

Biological factors

Genetic predisposition:

Strong evidence exists of genetic predisposition to schizophrenia, but some develop the disorder without family history. The more closely an individual is related to a person with the disorder, the higher the chances are of him developing it. According to studies, identical twins have a higher rate of developing the disorder than fraternal twins. Adoption studies show a higher concordance with biological parents than with adoptive parents.

But genetics is not the only cause; if it was, the concordance rate of schizophrenia in twins would be at 100 percent. Schizophrenia develops in adulthood. Men develop symptoms of schizophrenia in their late teens or early twenties, while women show symptoms of the disorder in their twenties or thirties. More subtle signs of the disorder maybe present earlier, such as poor performance in school, troubled relationships, and lack of motivation.

Brain abnormalities:

Brain scans of such individuals indicate a number of structural abnormalities. According to the Neurodegenerative Hypothesis, the destruction of neural tissue can cause schizophrenia. MRI studies have shown mild to moderate brain atrophy; a general loss or deterioration of neurons in the cerebral cortex and limbic system, together with enlarged ventricles (cavities containing cerebrospinal fluid).

The atrophy is centered in the brain region influencing cognitive process and emotion. This may explain the thought disorders and inappropriate emotions seen in such patients. Likewise, MRI images of the thalamus, which collects and routes sensory input to various parts of the brain, reveal abnormalities as well. This may help account for the disordered attention and perception reported by the patients whose cerebral cortex may be getting garbled with unfiltered information of the thalamus. These structural differences are more common in patients exhibiting negative symptoms.

Biochemical factors:

Dopamine, a major excitatory neurotransmitter, may play a key role in schizophrenia. According to the Dopamine Hypothesis, the symptoms of schizophrenia, specifically the positive symptoms, are produced by overactivity of the dopamine system in areas of the brain which regulate emotional expression, motivational behaviour, and cognitive function.

Individuals diagnosed with schizophrenia have more dopamine receptors on neuron membranes than non-schizophrenics. These receptors seem to be overactive to dopamine stimulation and additionally, the effectiveness of antipsychotic drugs used to treat this disorder are positively related to their ability to reduce dopamine-produced synaptic activity. Other neurotransmitter systems could be involved in this complex disorder, too. Considering the biochemical and brain findings concerning schizophrenia, it is not clear whether they cause the disorder or vice versa.

Psychological factors

Freud and other psychoanalytic thinkers' view of schizophrenia was that it is a retreat from unbeatable stress and conflict. To Freud, schizophrenia represented an example of an extreme defence mechanism of regression, in which such a person retreats to an earlier and more secure (even infantile stage) of psychological development, when faced with overwhelming anxiety. Other psychodynamic thinkers, focusing on the interpersonal withdrawal, which is an important feature of schizophrenia, tend to view the disorder as a retreat from an interpersonal world that’s too stressful to deal with.

Even though Freud’s explanation on regression hasn’t received much direct research support, the belief of stress as a causal factor is accepted today. Some cognitive theorists believe that people with schizophrenia have a defect in the attention mechanism which filters out irrelevant stimuli, making them feel overwhelmed by both internal and external stimuli and in turn, causing sensory input to become a chaotic flood, resulting in irrelevant thoughts and images flashing into consciousness. The stimulus overload produces distractability, thought disorganisation, and a sense of being overwhelmed by disconnected thoughts and ideas.

As one schizophrenic noted, “Everything seems to come pouring in at once…I can’t seem to keep  anything out” (Carson). The recent MRI findings on thalamic abnormalities described earlier may help explain how the stimuli overload could occur through a malfunction of the brain's switchboard.

Environmental factors

Stressful life events seem to play an important role in the emergence of schizophrenic behaviour. Two to three weeks preceding a 'psychotic break', when acute signs of schizophrenia appear, these events tend to cluster. Stressful life events seem to interact with such a person's personality or biological vulnerability factors. A highly-vulnerable individual may require just a small stressful event to reach the breaking point. In a study, psychotic and non-psychotic individuals rated their emotional responses as they encountered stressful events in their daily lives. The psychotic individuals' reactions to their stresses were more intense with negative emotions, suggestive of emotional overactivity being a vulnerability factor.

Family dynamics have for long been a prime suspect in the origins of this disorder, but the search for characteristics of a parent or family causing the disorder has largely been unsuccessful. Significantly, children with biologically normal parents who are raised by adoptive parents with the schizophrenic disorder do not show an increased risk of developing the disorder. Although schizophrenic individuals often are from families with problems, the nature of the seriousness of such problems is not different from those of which non-schizophrenics are raised.

This does not mean that family dynamics are unimportant; it may just mean that a person must have a biological vulnerability factor in order to be affected by stressful family events to such a degree. There is indeed evidence that this vulnerability factor may appear early in life. In a study conducted by researchers, pre-schizophrenic children and their non-schizophrenic brothers and sisters were analysed using home movies of schizophrenic children. Even at these early ages, sometimes a child as young as two years old seem to show more odd and uncoordinated movements and less emotional expressiveness, especially for positive emotions. These odd behavioural patterns may not just reflect a vulnerability factor, but may also help create environmental stress by evoking negative reactions from others.

Although researchers have had difficulty pinpointing family factors contributing to the initial appearance of this disorder, one finding is consistent of previously-hospitalised schizophrenics being more likely to relapse when returned to a home environment that is high in a factor called 'Expressed Emotion'. Expressed emotion involves high levels of criticism, hostility, and over-involvement. One review of 26 studies showed that within 9-12 months of returning home, an average relapse of 48% in patients with  families who were high in expressed emotion, compared with a relapse rate of 21% with families that were low in this factor.

However, before we conclude on high expressed emotions causing relapses in patients, there is a finding from another study worth noting; which are videotapes of actual interactions between patients and their families. Analysis of the videotapes revealed that families who were high in expressed emotion did indeed make more negative comments to patients when they engaged in strange behaviours, but they also showed these patients behaving around four times as many strange behaviours, clouding the issue of what causes what. Thus, high expressed emotion may be a cause of a response to these patients' disordered behaviours; because people with this disorder can be overly sensitive to stress and even mildly negative family reactions could trigger underlying biological vulnerabilities, resulting in a relapse.

Sociocultural factors 

Sociocultural factors are undoubtedly linked to schizophrenia. According to many studies, the highest prevalence of schizophrenia is found in lower socioeconomic populations.Why is this? Is schizophrenia caused due to poverty, or is it an affect of the disorder? Two views tend to give opposite answers. The Social Causation Hypothesis attributes the higher prevalence of schizophrenia  to the higher levels of stress experienced by low-income people, particularly in urban environments.

In contrast, the Social Drift Hypothesis proposes that with the development of schizophrenic disorder, these individuals' personal and occupational functions tends to deteriorate, causing them to drift down the socioeconomic ladder into poverty and migrate to economically depressed urban environments. Perhaps both social causation and social drift maybe at work, for the factors linking poverty, social and environmental stressors, as well as schizophrenia, are undoubtedly complex.

In contrast to most disorders, schizophrenia may be a culture-free disorder. According to a worldwide epidemiological study sponsored by the World Health Organisation, the prevalence of schizophrenia  is not dramatically different throughout the world. Researchers have, however, found that the likelihood of recovery is greater in developing countries than in the developed nations, such as North America and Western Europe. This may be due to stronger community orientation and greater social support extended to disturbed individuals in developing countries.

Schizophrenia reflects complex interactions among psychological, biological, and environmental factors and presents prominent causal factors identified by analysis. Some patients do well with treatment and live productive lives, while others continue to be symptomatic. As this disorder starts in early adulthood, these individuals can benefit from rehabilitation and help them develop management skills, complete education or vocational training, and hold onto a job. This helps with self-sufficiency in people afflicted with schizophrenia.

There is no cure for schizophrenia, but management of symptoms with medication, cognitive behavioural therapy, and supportive psychotherapy. Substance abuse is high in schizophrenic patients, owing to the misuse of drugs, which can make diagnosis harder.