The interactionist approach to schizophrenia
Put simply the interactionist approach (also sometimes called the 'biosocial approach') is an
approach that acknowledges that there are biological, psychological and societal factors in the
development of schizophrenia. Biological factors include genetic vulnerability and neurochemical
and neurological abnormality. Psychological factors include stress, for example, resulting from life
events and daily hassles, including poor quality interactions in the family.
Explaining the interactionist approach: The diathesis-stress
model
Diathesis means vulnerability. In this context stress simply means a negative psychological
experience. The diathesis-stress model says that both a vulnerability to schizophrenia and a stress
trigger are necessary in order to develop the condition.
One or more underlying factors make a person particularly vulnerable to developing schizophrenia,
but the onset of the condition is triggered by stress.
Meehl's model In the original diathesis-stress model (Meehl 1962) diathesis (vulnerability) was
entirely genetic, the result of a single "schizogene'. This led to the development of a biologically
based schizotypic personality, one characteristic of which is sensitivity to stress. According to Paul
Meehl, if a person does not have the schizogene then no amount of stress would lead to
schizophrenia. However, in carriers of the gene, chronic stress through childhood and adolescence,
in particular the presence of a schizophrenogenic mother (see page 208), could result in the
development of the condition.
The modern understanding of diathesis One way in which our understanding of diathesis has
changed is that it is now clear that many genes each appear to increase genetic vulnerability slightly;
there is no single "schizogene' (Ripke et al. 2014). Modern views of diathesis also include a range of
factors beyond the genetic, including psychological trauma (Ingram and Luxton 2005) - so trauma
becomes the diathesis rather than the stressor. Read et al. (2001) proposed a neurodevelopmental
model in which early trauma alters the developing brain. Early and severe enough trauma, such
as child abuse, can seriously affect many aspects of brain development. For example, the
hypothalamic-pituitary-adrenal (PA) system can become over-active, making the person much more
vulnerable to later stress.
The modern understanding of stress In the original diathesis-stress model of schizophrenia, stress
was seen as psychological in nature, in particular related to parenting. Although psychological stress,
including that resulting from parenting may still be considered important, a modern definition of
stress (in relation to the diathesis-stress model) includes anything that risks triggering schizophrenia
(Houston etal 2008). Much of the recent research into factors triggering an episode of schizophrenia
has concerned cannabis use. In terms of the diathesis-stress model cannabis is a stressor because it
increases the risk of schizophrenia by up to seven times according to dose. This is probably because
cannabis interferes with the dopamine system. However, most people do not develop schizophrenia
after smoking cannabis so it seems there must also be one or more vulnerability factors.
Put simply the interactionist approach (also sometimes called the 'biosocial approach') is an
approach that acknowledges that there are biological, psychological and societal factors in the
development of schizophrenia. Biological factors include genetic vulnerability and neurochemical
and neurological abnormality. Psychological factors include stress, for example, resulting from life
events and daily hassles, including poor quality interactions in the family.
Explaining the interactionist approach: The diathesis-stress
model
Diathesis means vulnerability. In this context stress simply means a negative psychological
experience. The diathesis-stress model says that both a vulnerability to schizophrenia and a stress
trigger are necessary in order to develop the condition.
One or more underlying factors make a person particularly vulnerable to developing schizophrenia,
but the onset of the condition is triggered by stress.
Meehl's model In the original diathesis-stress model (Meehl 1962) diathesis (vulnerability) was
entirely genetic, the result of a single "schizogene'. This led to the development of a biologically
based schizotypic personality, one characteristic of which is sensitivity to stress. According to Paul
Meehl, if a person does not have the schizogene then no amount of stress would lead to
schizophrenia. However, in carriers of the gene, chronic stress through childhood and adolescence,
in particular the presence of a schizophrenogenic mother (see page 208), could result in the
development of the condition.
The modern understanding of diathesis One way in which our understanding of diathesis has
changed is that it is now clear that many genes each appear to increase genetic vulnerability slightly;
there is no single "schizogene' (Ripke et al. 2014). Modern views of diathesis also include a range of
factors beyond the genetic, including psychological trauma (Ingram and Luxton 2005) - so trauma
becomes the diathesis rather than the stressor. Read et al. (2001) proposed a neurodevelopmental
model in which early trauma alters the developing brain. Early and severe enough trauma, such
as child abuse, can seriously affect many aspects of brain development. For example, the
hypothalamic-pituitary-adrenal (PA) system can become over-active, making the person much more
vulnerable to later stress.
The modern understanding of stress In the original diathesis-stress model of schizophrenia, stress
was seen as psychological in nature, in particular related to parenting. Although psychological stress,
including that resulting from parenting may still be considered important, a modern definition of
stress (in relation to the diathesis-stress model) includes anything that risks triggering schizophrenia
(Houston etal 2008). Much of the recent research into factors triggering an episode of schizophrenia
has concerned cannabis use. In terms of the diathesis-stress model cannabis is a stressor because it
increases the risk of schizophrenia by up to seven times according to dose. This is probably because
cannabis interferes with the dopamine system. However, most people do not develop schizophrenia
after smoking cannabis so it seems there must also be one or more vulnerability factors.
