Lecture 3 1/26/10 Neurocognitive Deficits and Schizophrenia Splitting of the mind?s functions Symptoms also exist in other disorders What makes it Schizophrenia and not bipolar? Neurocognitive deficits ? Trait Neurodevelopmental disorder Failure to develop at normal level Why late onset? Wineberger Onset of development of legion (early, prenatal) Onset of manifestation (age 18-25) Early signs exist in some individuals What is executive functioning? Higher order cognitive processes involving planning, abstraction, and complex reasoning Patients with Schizophrenia display deficits Wisconsin Card Sort Task Deficits in executive functioning: Focusing attention Inhibition Task management Set shifting Planning and implementing behavior Monitoring and updating Working memory Holding info in temporary storage, manipulating it and using it to guide subsequent behavior Requires holding info online (short term memory) Active manipulation of info, particularly as memory load increases Baddeley?s Model of WM Smith and Jonides (1999) Modification Central Executive Central Executive Visuospatial WM Verbal WM Object Spatial Verbal Visual Images Speech-based Info Features Location Verbal Info Types of Working Memory Tasks Spatial ? maintaining the spatial location of a stimulus over a delay period Object ? maintaining features of object over delay period Verbal ? maintaining verbal info (letters, words, numbers) over delay period Effect Sizes Refers to the magnitude of difference between 1 group of people and another group on some measurement Cohen?s d ? average of group 1 subtracted from avg. of group 2, divided by pooled standard deviation Mean(group 1) ? Mean(group 2) Standard deviation (pooled) Greater than .8 is better d = .80 overlap 53% about half of group 1 and half of control group are indistinguishable Evidence of frontal lobe deficits in Schizophrenia Wisc. Card Sort 0.88 Word fluency 1.09 Stroop Test 0.97 Tower of London 1.05 Spatial WM 2.09 Perseveration (opposite of fluency) ? repetition Schizophrenia ? reduced output with word fluency Article Summaries: Park and Holzman (1992) 1st study of working memory in patients with schizophrenia Adapted a delayed response task previously used with Rhesus monkeys 2 oculomotor tasks: oculomotor memory and sensory tasks Participants, 3 groups: Patients with schizophrenia (n = 12) Patients with bipolar (n = 12) Normal controls (n = 13) Results Patients with schizophrenia had impaired memory-guided responses No impairment on sensory-guided tasks Impaired in the haptic domain as well as spatial domain Conclusions Patients with schizophrenia have deficits in representational processing Glahn et al. (2003) Research questions: Does performance on spatial WM task vary with memory set size (memory load)? Is performance on spatial WM task affected by genetic predisposition to Schiz? Methods Compared patients with Schizophrenia (probands), MZ co-twins, DZ co-twins, and 42 healthy control twins Spatial WM task performance Varied memory set size (memory load) of SWM tasks Results Group performance varied as function of genetic risk Probands performed worst SWM performance decreased with increased genetic liability In terms of performance, MZ co-twins discordant for Schizophrenia did not differ significantly from each other Performance on task is heritable Across all groups, performance on SWM task decreased with increasing set size Important because we don?t have a test to tell someone that they are at risk for Schizophrenia (no blood test, etc.) Work towards identifying genes, treatment and prevention Gooding and Tallent (2004) Methods, 3 groups: Schizophrenia patients (n = 24) Schizoaffective patients (n = 12) Healthy controls (n = 29) 3 Working Memory Tasks: Spatial WM ? match location of target Identity WM (Object) ? match identity of target Emotion WM (experimental, Object) ? match emotion of target Schizophrenia patients have emotion processing problems Results: Schizophrenia and schizoaffective patients have similar WM performance Compared to healthy, performance is poorer on all 3 WM tasks Conclusion: WM impairment in Schizophrenic patients extends beyond Spatial domain Elvevag and Goldberg (2000) Review paper regarding cognitive deficits Different types of attention Focused ? ability to respond discretely to specific visual, auditory, or tactile stimuli (small external validity) Divided ? ability to simultaneously respond to multiple tasks Selective ? ability to maintain cognitive set, requires activation and inhibition of responses, discriminate stimuli Sustained ? maintain consistent behavioral response during continuous or repetitive activity (follow a conversation, study, etc.) Continuous Performance Test (CPT) measures sustained attention Most frequently tested in people with schizophrenia, impaired All forms of attention are impaired in schizophrenia Early Visual Processing Sustained Attention Working Memory Verbal Learning and Problem Solving Long Term Memory Social Cognition Verbal learning ? repeat list of words (immediate recall), switch list (interference), remember 1st list (delayed recall) Working memory ? repeat list of numbers backwards (temporary storage) Long term memory ? repeat action 30 minutes alter Working memory is used to facilitate verbal and long term memory Sustained attention facilitates WM Verbal learning ? don?t use memory/mnemonic strategies as efficiently Deficits also in non-verbal memory ? multiple aspects of cognition are impaired
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