Metacognition and insight in health, psychosis and dementia : relationship with mood and neurocognition

Lack of awareness of illness (insight) is a well recognised problem in clinical syndromes such as first episode psychosis and dementia. In healthy persons, ability to accurately rate our thoughts and behaviours is also often referred to as metacognition and there is also some debate as to whether the accuracy of our self-awareness diminishes during healthy ageing. Low mood is often noted to be associated with better insight in clinical groups, however it is not clear whether this also mediates awareness is healthy adults. Some aspects of insight are also mediated by cognitive abilities; more work is required in this area in healthy adults. Awareness and metacognition are often used interchangeably in the clinical literature, despite the methods differing drastically between healthy and clinical awareness studies. The aims of this thesis were: - to investigate the similarities and differences between insight and experimental measures of metacognitive efficiency across the adult life span and in patients experiencing their first episode of psychosis (FEP), early-stage dementia (ED) and depression. - to quantify the insight and metacognitive functional abilities and deficits in these groups. - to investigate the effect of mood and cognitive abilities on insight and metacognitive efficiency. - to run a pilot neuroimaging study aimed at investigating the structural neural correlates of both cognitive insight and metacognitive efficiency in ED patients. Both clinical measures of insight and experimentally derived metacognitive tasks were used. Results indicate age, memory and mood mediate metacognitive efficiency in healthy adults, with small associations between metacognitive efficiency and some measures of insight when controlling for age. In patients, results suggest that mood is associated with cognitive insight in FEP, but not metacognitive efficiency in either early dementia or psychosis. Further, there was an association between cognition and metacognitive efficiency in FEP, but not ED. There was no association between insight and metacognitive efficiency in either patient group. Comparing groups, FEP patients have worse metacognitive efficiency that healthy younger adults but not insight, whereas there was no difference between ED and healthy older adults. FEP patients appear to have better self-reflection on clinical scales than ED patients, whereas there was no difference between the two groups in metacognitive efficiency. The imaging study indicated that measures of cognitive insight and metacognitive efficiency have overlapping structural correlates in the cortical midline structures. Implications for these findings in both healthy adults and patients are discussed.