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Professor Eileen Joyce delivers prestigous 2012 Paykel Lecture in Psychiatry
The 2012 Paykel lecture in Psychiatry, entitled ’The Cognitive Impairment in Schizophrenia: Neural Basis and Clinical Relevance”, was given this week by Professor Eileen Joyce, Professor of Neuropsychiatry at UCL.
Professor Joyce (pictured left), who is also Chair of the British Neuropsychiatry Association, began with a short history of schizophrenia research, from Freud through the sociology of the 1960s to the biological focus reinvigorated in 1980 by TJ Crow, who postulated that altered dopamine signalling, known to be implicated in schizophrenia, was only one facet of the disorder, albeit an important one.
Schizophrenia currently affects 24 million people worldwide, most of whom are in the age range 15-35 years. It is characterised by a breakdown of mental processes, which can include a variety of symptoms, often referred to as ‘negative’ and ‘positive’ symptoms. Negative symptoms can include lack of motivation, blunted affect, and reduced desire whereas positive symptoms describe experiences such as delusions and hallucinations.
A four year prospective study carried out by Joyce and colleagues and published in 2009, demonstrated strikingly that cognitive impairment is a static facet of schizophrenia. Patients followed up at year 1 and year 4 showed reduced negative and positive symptoms following treatment, whereas IQ remained stable. Cognitive function therefore, was shown not to track symptom severity, nor to be affected by schizophrenia medication.
Since those findings, the Joyce group have demonstrated that IQ at schizophrenia onset is an effective predictor of clinical outcome.
One of the most striking findings from the Joyce group is that cognitive impairment predates onset. Premorbid IQ has been shown to be impaired during development and present before the onset of schizophrenia. Furthermore, lower IQ is linked to a lowered age of schizophrenia onset.
IQ trajectory was also shown to be important. A study from Professor Joyce’s research team compared the outcomes of people whose IQ was classed as low, preserved or deteriorated. Three years later, both the low and the deteriorated groups showed longer index admissions, more core negative symptoms, and were less likely be employed.
Throughout the talk, Professor Joyce provided convincing evidence that impaired cognition is a key facet of schizophrenia, that IQ can be used to predict outcomes 3-4 years later, and that the cognitive impairment may be related to structural abnormalities in the cortex. General IQ, as opposed to any specific IQ subset is the most reliable predictive factor.
One theory that may go some way to explain this is the cognitive reserve hypothesis, which refers to the brain’s defence against damage being more effective in people with higher cognitive ability. Professor Joyce referred to a 2006 study led by a member of our department, Dr Jenny Barnett, in which it was reported that higher cognitive reserve resulted in fewer symptoms in mental illness. This explanation links clinical outcome and cognitive function to brain structure and may explain the changes in cortex that are seen in some people with schizophrenia.
Posted on 04/10/2012
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