Freud (1924) suggested that Schizophrenia is a result of two related processes.
1. Regression to a pre-ego stage
2. Attempts to re-establish ego control
He suggested that the disorder is seen as an infant style stage by symptoms such as delusions to reflect a primitive condition.
He said that regression to the oral stage could result in a self centered disorder as the person lives their life in a state of self-absorption.
It is reductionist as it doesn't take on the role of genetics/biological factors and is also deterministic as it states we have no control over our behaviour as its all down to childhood experiences. The research he did was very specific to the cases he looked at so would find it difficult to generalise to others.
This explanation aknowledges the role of bioligy in the initial sensory symptoms that a patient may experience. It also claims that other symptoms are a result of the individual attempting to rationalise the symptoms.
It says when a schizophrenic experiences a scary sensory experience like a hallucination they will turn to others to confirm the validity of what they are experiencing, when of course the person they turn to cant validate it they assume people are trying to hide the truth from them, they may then develop delusions that they are being persecuted by others around them.
There is lots of research to support the initial sensory experiences caused by biology e.g the excess Dopamine D2 Receptors and over activity of dopamine in the brain.
Bateson et al (1956) suggested that children are likely to develop schizophrenia if they frequently recieved contradictory messages from their parents. For example if a mother tells her son she loves him but turns her head away in disgust at the same time, both these messages conflict.
These conflicting messages then lead to the child development of a internally coherent construction of reality which over the long term can lead to schizophrenia.
Berger et al (1965) supported the link by finding that schizophrenia patients reported a much higher level of double-bind statements by their mothers then non-schizophrenics.
There is significant research to suggest that stressful life events can trigger schizophrenia. Brown and Birley (1968) found that prior to a schizophrenic episode, patients reported twice as many stressful events than a healthy group.
This model then leads to the idea that biology is also involved through the arousal of a neurotransmitter in the brain triggered by stress.
However there is conflicting evidence as not all studies have found a link between stress and schizophrenia. The link is also correlational so therefore finding things more stressful could be an onset of a schizophrenic episode.