An investigation of the interaction between schizotypy and cognitive monitoring processes

The concept of ‘theory of mind’ (or mentalising ability) refers to the capacity to attribute mental states to others in order to explain what they did, or predict what they will do. The role of theory of mind has been extensively researched in relation to autism and is thought to explain some of the social and communication abnormalities that are present in the disorder. C. Frith (1992) broadened the definition of mentalising to include the ability to represent one’s own as well as others actions, and suggested that all of the commonly observed symptoms of schizophrenia could be understood as a result of a breakdown in the person’s capacity to mentalise. The research presented in this thesis aimed to assess Frith’s theory by comparing individuals who were found to be high and low in schizotypy. It was hypothesised that individuals who demonstrated high scores on measures of schizotypy would show poorer ability to generate willed action, and to monitor their own, and others mental states. Mentalising abilities were assessed using four tasks: in the triangles task participants watched a series of computerised animations involving two shapes which engaged in increasingly complex sequences of interaction. Participants were asked to describe what they thought was taking place and their descriptions were used to assess their ability to employ theory of mind in relation to others. Participants then completed the me-pulse; a novel task which involved a variant on the prepulse inhibition paradigm; the Flayling test, and a go/No go task. The results broadly supported Frith’s theory. On the triangles task, the high schizotypes imputed ‘theory of mind’ significantly more than low schizotypes when the shapes were moving randomly. On the Hayling test high schizotypy participants took significantly longer to complete both parts of the test than the low schizotypes. On the go/No go task, the high schizotypy group 6 made significantly more false alarms, indicating deficits in their ability to set shift and inhibit their responses. On the me-pulse task the low schizotypy participants showed a decrease in magnitude of response when the startling stimulus was self­ initiated, in contrast the high schizotypy participants actually showed increased response amplitude in response to self-generated stimuli. Taken together, these results indicated support for the hypothesis that high schizotypes showed deficits in their ability to generate willed action, and to monitor the mental states of both others and themselves. The marked difference in the pattern of results between the two groups of participants provides further support for the concept of schizotypy. The fact that these anomalies in mentalising ability are seen in a non psychiatric population indicated some support for the idea of mentalising defects as a trait marker for psychosis, rather than simply a manifestation of the psychotic state. Chapter 1: Introduction It is almost one hundred years since Kraepelin (1919) described ‘dementia praecox’, the illness we now know as schizophrenia. Understanding schizophrenia has proven to be a challenge to clinicians throughout this century and classification systems and diagnostic markers have been subject to refinements and change (Andreasen, 1997). Whilst our understanding of the illness has advanced considerably since Kraepelin’s day, there is still no ‘cure’ as such, and schizophrenia continues to challenge those who live and work with it. Schizophrenia affects the lives of around one in a hundred people. The treatment that can be offered to patients has advanced considerably since the days when a diagnosis led to confinement in an asylum, often for the rest of one’s life, within which patients were sometimes exposed to therapies that were ineffectual, or downright dangerous. Consider for example the insulin comas into which schizophrenic patients were induced, in order that they might ‘sleep off’ their illnesses. In fact there was generally no conceivable benefit (Ackner, Harris & Oldham, 1957). Today, continuing refinements in neuroleptic medication have lead to the development of atypical anti-psychotics such as risperidone, olanzapine, and clozapine, which have enabled many more sufferers to resume their lives in a way that would once have been impossible. However, these medications are not without side effects, some of which are perceived as so debilitating that some patients do not adhere their medication regime. In a meta-analysis considering the adherence of over 23, 000 non-compulsory patients treated for schizophrenia since 1980, Nose, Barbui and Tansella (2003) found on overall rate of non-adherence to treatment of 25.8%. A study by Lacro, Dunn, Bolder, Leckband and Jeste, (2002, cited in Nose et al., 2003) which looked simply at adherence to medication (rather than to scheduled appointments also, like Nose et al., 2003) and used tighter inclusion criteria, found that 41.2% of patients did not adhere. Non adherence to treatment has been found to have a major impact on the efficacy of treatment for psychotic disorders which tend to require contact with services over the long term in order for the patient to remain stable. Non adherence is associated with poorer outcome and increased rates of hospital admission (Gray, Wykes, & Goumay 2002, cited in Nose et al., 2003). All mental health practitioners will be familiar with the phenomena of the ‘revolving door patient’ someone whose illness is stabilised on medication whilst in hospital, but who does not adhere to their treatment programme when they return to the community, only to experience once more, such a profound deterioration in their mental state that others deem that they must return to hospital and recommence medical treatment, frequently against their will. Repeated episodes of this type are distressing to patients, and can lead to a hardening of their attitudes toward mental health professionals. In the context of such difficulties, psychologists have been producing a growing body of work which aims to identify the cognitive deficits underlying schizophrenia. The hope is to develop psychological treatments aimed at ameliorating symptoms and preventing relapse, and there is evidence to support the use of cognitive behavioural approaches in particular (Kuipers et al., 1998). This thesis aims to contribute further to our understanding of the symptoms that schizophrenia patients experience through an investigation of mentalising processes in individuals high in schizotypy. In this introductory chapter, I will consider the 9 debate as to whether the cognitive deficits shown by schizophrenia patients are global, or specific in nature. There will then follow an introduction to the ideas of C.Frith (1992) who has suggested that a specific deficit in terms of mentalising, or theory of mind, accounts for all of the signs and symptoms of schizophrenia. The existing literature on mentalising processes in schizophrenia will be reviewed, focusing on whether they show support for, or challenge, the theoretical account of Frith (1992). The concept of schizotypy will then be introduced and Frith’s account re-visited in terms of schizotypy. A critical evaluation of the literature then leads to the rationale for the empirical research of this thesis which concerns theory of mind, not only in relation to others, but also in relation to self. The literature review is not exhaustive but focuses on the ability to monitor the actions and intentions of both the self and others. Deficits in schizophrenia; Global or Specific? The role of 10 and Executive Functioning in Schizophrenia. Researchers have debated the issue of whether the cognitive deficits exhibited in schizophrenia patients are specific, or more global in nature. Studies which have considered the role of IQ and of executive functioning are essentially posing this question. Certainly, studies have consistently shown that people with schizophrenia exhibit poor performance across a wide range of neuropsychological tests, for example Heinrich and Konstantine (1998, cited in Townsend, Malla, & Norman, 2001) conducted a meta-analysis of 204 studies of schizophrenic patients which had been published over a seventeen year period, and concluded that schizophrenia is marked by the presence of a broad range of cognitive deficits. However, there is still a debate 10 about the precise nature and onset of these deficits in relation to the onset of illness. In comparison to chronic schizophrenic patients, first episode patients show much better performance on cognitive tests and minimal impairment in executive functioning (Hutton et al., 1998, cited in Townsend et al., 2001) suggesting that progression of the illness goes hand in hand with a deterioration in functioning. However, comparisons of first episode patients and chronic patients are fraught with complications, since chronic patients have often been institutionalised, and have generally been taking medication for many years. Researchers have tried to address these confounding variables by assessing first episode patients in comparison to healthy controls. It remains difficult to draw firm conclusions from the literature since studies still vary in terms of the nature of the sample under consideration (hospital or community based? ) the measures used to assess, and medication status (neuroleptic naïve or not? ) (Townsend, et al., 2001) Mohamed, Paulsen, O’Leary, Arndt, and Andreasen, (1999) studied first episode patients who were neuroleptic naive, using a battery of tests which assessed a wide range of cognitive functions, and concluded that they showed substantial impairments in multiple areas, including learning, attention, processing speed and executive functioning. Given that the patients were in an early phase of their illness, and had never been medicated, Mohamed et al. (1999) concluded that widespread cognitive dysfunction must be primary, and cannot be attributed to long term il