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Discussion about the aetiology or cause of schizophrenia has over the years generated much debate. This debate is reflected in the diverse areas upon which investigation for the cause of schizophrenia has focused. This section will briefly identify and describe the following suggested causes of schizophrenia: genetics;
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biochemical; the family; behavioural; cognitive; neurological; and, sociological factors. The diathesis-stress model is also described and discussed.
Genetics
Geneticists have investigated schizophrenia by observing the rates of schizophrenia across families (Bernheim & Lewine, 1 979). Evidence provided by investigating the prevalence of schizophrenia in specific populations (see Table 1
below), and adoption studies (Kety, Rosenthal, Wender, & Schulsinger, 1 968; Rosenthal, Wender, Kety, Schulsinger, Weiner, & Ostergaard, 1 968; Wender, Rosenthal, Kety, Schulsinger, & Weiner, 1 974), suggest that genetics plays a definite role in the development of schizophrenia. A pure genetic explanation for schizophrenia would have a concordance rate of 1 00 percent in monozygotic twins. In other words, every time that one identical twin had schizophrenia, so would the other twin. As is indicated in Table 1 below, the concordance rate for monozygotic twins has been found to be forty-seven percent. This means that genetics does not completely explain the presence of schizophrenia.
Table 1. The prevalence of schizophrenia in specific populations (Kaplan & Sadock, 1 991 :328)34.
POPULATION PREVALENCE
* General 1 .0
* Nontwin of a 8.0
* Child with one 1 2.0
* twin of a 1 2.0
* Child of two 40.0
* twin of a 47.0
Biochemical
It is a person's biochemistry which is the focus of biochemical explanations for the cause of. schizophrenia. Ever since the first clinical definition of schizophrenia, focus has been on a biochemical cause. Kraepelin speculated about poisons secreted from the sex glands, and Jung proposed the effects of 'toxin X' (Davison 34 Statistics focusing on the prevalence of schizophrenia in families vary depending on which
26 & Neale, 1 986). Nearly every known neurotransmitter, the body's chemical
messengers, has been studied for its possible link to schizophrenia (Kaplan &
Sadock, 1 991 ). The neurotransm itter dopamine has held a prominent position in this biochem ical research. Findings of this research suggest a link between schizophrenia and an excess of dopam ine in particular parts of the brain (Kaplan
& Sadock, 1 991 ). The newer more effective neuroleptic medications however act
to block both dopamine and serotonin receptors (Janssen-Cilag, no dateb; Meltzer, 1 992a; Reed Healthcare Australia, no dateb). The most researched neurotransm itters besides dopamine are: serotonin; phenylethylamine (PEA); noradrenaline; methylated amines; acetylcholine; gamma-aminobutyric acid (GABA); and, neuropeptides. Although results of these studies have yet to provide a body of reliable and valid evidence (Birchwood et ai, 1 988), the most effective treatment currently available for schizophrenia primarily attempts to control the symptoms of schizophrenia by acting upon neurotransmitters and their receptor sites. As will be explained below, neuroleptic medications, or drug therapy, are considered to be the most effective treatment for schizophrenia. Role of the Family
'The family' has traditionally been considered a causal agent of an individual's schizophrenia. This is highlighted" by Lamb, Hoffman, Hoffman, & Oliphant's (1 986) who make the comment that families have been blamed for their family mem ber's schizophrenia. Four main theories have related family influences to the existence of schizophrenia:
1 ) 'Schizophrenogenic mother' was a term developed by Fromm-Reichmann ( 1 948):
... to denote a domineering, cold, rejecting, possessive, guilt producing person, who in combination with a passive, detached, and ineffective father, causes her male offspring to feel confused and inadequate and ultimately to become schizophrenic (Goldenberg & Goldenberg, 1 985:99).
Although the 'schizophrenogenic mother' theory describes a combination of a cold dom ineering mother, and a passive detached father, the implications of this theory have been particularly harsh for mothers. As the title 'schizophrenogenic mother' suggests, mothers in particular have been
27 considered to be the causative agent within the family. The current understanding is that there is no scientific evidence to support the 'schizophrenogenic mother' theory (Keefe & Harvey, 1 994). However, discussion in this chapter will argue that despite this understanding, mothers are still considered by lay persons and some mental health professionals as a causative agent of a family member's schizophrenia. Further, it will be asserted that this understanding has hindered the informal care provision of mothers to their adult children.
2) The 'double bind' comm unication theory proposes that a child exhibits the
symptoms of schizophrenia when they continually are put in the position where they must choose between two alternatives, each alternative resulting
in negative consequences (Bateson, Jackson, Haley & Weakland, 1 956).
An example of the
double-bind communication theory is when a mother intimates to her child that she wants to embrace the child. However, when the child attempts to hug h is mother the mother withdraws from her child's touch. In this case, the child disobeys his mother's verbal or non-verbal instructions no matter what
action he takes. ;
3) Families which are either 'schismatic' or 'skewed' have been considered to have the potential to cause schizophrenia among their members. 'Schismatic families' are those in which one parent becomes overly close to their child, . causing a schism between the parents. In 'skewed families' a power struggle exists between the parents (Lidz, Cornelison, Fleck & Terry, 1 957).
4) The 'expressed emotion' (EE) theory proposes that persons diagnosed with schizophrenia are more likely to experience relapse if their environment is negatively charged, especially with negative criticism (Brown, Mench, Carstairs, Wing, 1 962). Although the EE theory does not identify the family as the cause of their member's schizophrenia, this theory does implicate the family in maintaining the expression of the symptoms of schizophrenia. Hatfield (1 987:341 ) has argued that the EE theory has the following implication for families:
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Families who have long protested the idea that they are pathological agents in the cause of mental illness are now faced with the notion that they are pathological agents in maintaining it.
In endeavouring to prevent their family member from experiencing an acute episode of schizophrenia, It is likely that care-givers, aware of the EE theory, would monitor the emotional environment within the household. It could also be argued that in maintaining a stable and positive emotional environment, the care givers' own emotional expression around the family members could come under scrutiny. Care-givers may need to constantly monitor and restrict their own emotions in order to ensure that they do not negatively charge their family members' environment.
One main question about the validity of these theories describing the role of the family in relation to schizophrenia, is whether these family patterns are actually the cause of, or the response to, a family member being diagnosed with schizophrenia. Further implications for informal care provision of the discourses associated with these theories about family aetiology will be noted· further on in
this chapter. "
In summary, the 'schizophrenogenic mother' theory, double-bind communication theory, and 'schismatic' and 'skewed' family theory, are considered weak explanations for the causation of schizophrenia (Davison & Neale, 1 986;
Goldenberg & Goldenberg, 1 985; Higgens, 1 966; Keefe & Harvey, 1 994; Straus & Carpenter, 1 98 1 ). The level of expressed emotion within the family does however seem to have some influence on whether an individual continues to express schizophrenic symptoms and their rate of relapse (Atkinson, 1 986; H udson, 1 982;
Kuipers & Bebbington, 1 987; Seeman et ai, 1 982). Cognitive
Cognitive theory looks at the inability of those who exhibit the symptoms of schizophrenia to maintain attention and filter out distracting stimuli. For example, McGhie and Chapman ( 1 961 ) have assumed that the basic problem in schizophrenia is an inability to select, focus on and regulate incoming information.
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The effects of these attentional deficits have been identified by, for example, Gold and Harvey (1 993). These researchers found that people exhibiting the symptoms of schizophrenia reliably demonstrated deficits in their attention, memory and problem solving. Despite the various evidence associated with the attentional deficit theory (Hudson, 1 982; Perry & Braff, 1 994; Shean, 1 978), there still needs to be some form of longitudinal study to produce stronger evidence. It is equally plausible, for example, that these phenomena are a result of a deeper process also producing schizophrenia.
Neurological
Some research has indicated that persons diagnosed with schizophrenia are likely to have neurological differences in their brain, not found in the 'normal' population. Examples of these differences are: atrophy of the hippocampus, thalamus and cerebral cortex; reduced levels of brain metabolism especially in the temporal and frontal areas of the brain, and larger ventricles (Davison & Neale, 1 986; Kalat, 1 992; Keefe & Harvey, 1 994; Lezak, 1 995; Nestor, Shenton, McCarley, & Haimson, 1 993). Again, the question needs to be answered as to whether these neurological differences explain the schizophrenia, or if the schizophrenia explains the neurological differences . .;
Sociological
Sociological theories move away from the tradition of focussing on the individual in order to explain mental illness. Szasz ( 1 976) for example, states that schizophrenia is a myth. It is not a disease, since no physical cause can be found, but instead is the result of disagreement between the powerful and the less powerful. The label of 'schizophrenic' is applied in order to control behaviour which challenges the status quo. Szasz's (1 976) view of schizophrenia is largely ignored by researchers today. There is evidence for both the social causation hypothesis (Cochrane, 1 983) which proposes that being in a lower socio-economic class is a significant factor in causing illness, and the social selection hypothesis (Gottesman & Shields, 1 982) which states that having a psychiatric illness results in a person having a lower socio-economic position. Although it seems as though the social selection hypothesis is more valid, it is asserted that the social
causation and the social selection hypotheses are not mutually exclusive. In other words, both theories are equally capable of explaining how schizophrenia occurs (Cochrane, 1 983).
Diathesis-stress
The diathesis-stress model links both physiological and environmental factors in explaining the cause of schizophrenia. Atkinson (1 986:35) has explained that underlying the diathesis-stress model is the assumption:
... that to develop schizophrenia an individual needs to have a genetic predisposition to develop the disorder which is triggered by an environmental stress of some kind. This stress might come from upbringing, lifestyle, maturation and, indeed, anything in the individual's milieu.
Table 2 illustrates how diatheses and stressors interact. If a person is predisposed to a certain disorder, their environment will either reduce or increase the magnitude of this disorder. The diathesis-stress model is supported by the research examining the role of genetics in the cause of schizophrenia. As was noted above, this research (Kaplan & Sadock, 1 991 ) has indicated that some other factor(s) combine with genetics in order for an individual to exhibit the
, symptoms of schizophrenia.
Table 2. Components of the Diathesis-Stress Model.
Diathesis
Genetic dis sit ion
Stressors
Environmental stressors
Outcome
Disease/disorder
To conclude, there is no unitary, universally accepted explanation for schizophrenia. Reflecting this lack of consensus is the advice that a multi dimensional approach should be utilised when considering the aetiology of schizophrenia (Bellack 1 984). Utilising an eclectic approach to explain schizophrenia is also supported by the current view that schizophrenia is a heterogenous disorder • ... complicated by its complex and variable aetiology". (Reed Healthcare Australia, no date:4; see also Bentall, 1 992).
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