We aimed to examine the association between lifetime cannabis use and estimates of both premorbid... more We aimed to examine the association between lifetime cannabis use and estimates of both premorbid and current cognitive function in psychotic disorders in an Australian cohort. In an Australian multicenter cohort, 1237 participants with an established ICD-10 diagnosis of psychotic disorder were categorised according to history of lifetime cannabis use (non-users, n=354; cannabis users, n=221; cannabis dependency, n=662). Groups were analyzed according to available indices of cognitive ability: the National Adult Reading Test - Revised (NART-R) for ability prior to illness onset; and the Digit Symbol Coding Test (DSCT) for current ability. Two-way analysis of variance was conducted without any covariate, followed by a two-way analysis of covariance (using age, age at onset of psychiatric illness, premorbid IQ and the Socio-Economic Index for Areas (SEIFA) rankings). Whilst there appeared to be a significant association between cannabis use and mean DSCT (higher DSCT scores in cannabis using groups) F(2,1080)=9.478, p<0.001, η2=0.017), once covariates were used in the analysis there were no significant differences between groups in mean DSCT scores (F(2,1011)=0.929, p=0.395, η2=0.002). Similarly there were no differences between groups in mean NART scores once, age, age at illness onset and SEIFA rankings were used as covariates (F(2,1032)=1.617, p=0.199, η2=0.003). Confounding variables underpin the association between cannabis use and cognitive function in psychotic disorders. Taken together, it would appear that cannabis use or dependence has no additive effect on cognitive dysfunction in these disorders.
Background: In this study, we conducted a broad investigation of neuropsychological functioning i... more Background: In this study, we conducted a broad investigation of neuropsychological functioning in schizophrenia patients with first-rank (passivity) symptoms (FRS) using standardized cognitive tests. We focused on 3 neuropsychological domains, partly informed by 3 broad hypotheses concerning the pathogenesis of FRS. We tested predictions that patients with FRS would show: (i) memory deficits consistent with abnormalities in medial temporal lobe functioning; (ii) reduced cerebral lateralization on tasks of motor and language functions, and (iii) deficits on tasks of executive functions as a measure of the integrity of the prefrontal cortex for supporting self-monitoring processes. Sampling and Methods: In 2 parallel studies, we administered a range of neuropsychological tests to patients with FRS (sample A = 17, sample B = 15) and without FRS (sample A = 28, sample B = 20) and to healthy controls (sample A = 109, sample B = 22). Results: The results showed reduced cerebral lateralization in patients with FRS, but there were no memory deficits or executive dysfunctions relative to patients without FRS. An unexpected finding was that, on many cognitive tasks, the performance of the patients with FRS was relatively spared compared to that of the patients without FRS. These results could not be accounted for by demographic features or medication effects. Conclusions: Our results provide qualified support for the reduced lateralization hypothesis. Analyses of performance across neuropsychological domains showed that generalized deficit is not a sufficient explanation for the occurrence of FRS.
... Flavie AV Waters1''3" Johanna C. Badcock and Murray T. Maybery &am... more ... Flavie AV Waters1''3" Johanna C. Badcock and Murray T. Maybery 'School of Psychology and 2School of Psychiatry and Clinical Neurosciences, University of Western Australia; Centre for Clinical Research in Neuropsychiatry, Graylands Hospital, Perth; 4Neuroscience Institute ...
Journal of Nervous and Mental Disease, Dec 1, 2009
Memories of conversations are composed of what was said (speech content) and information about th... more Memories of conversations are composed of what was said (speech content) and information about the speaker's voice (speaker identity). In the current study, we examined whether patients with schizophrenia would show difficulties integrating speech content and speaker identity in memory, as measured in a gender-identity (male/female) recognition task. Forty-one patients and a comparison group of 20 healthy controls took part in the study. In contrast to controls, patients demonstrated greater impairments in memory for female, but not male, voices. These results are consistent with studies of speech perception that show that female voices have more complex "vocal" characteristics and require greater integration compared with male voices, and with the context memory hypothesis of schizophrenia which suggests that memory binding impairments may result in degraded or incomplete representations of memory traces as the task requirements become increasing complex.
The Embedded Figure Test (EFT) requires locating a simple shape embedded within a background of o... more The Embedded Figure Test (EFT) requires locating a simple shape embedded within a background of overlapping target-irrelevant scene elements. Observers with autism, or those with high levels of autistic-like traits, typically outperform matched comparison groups on the EFT. This research investigated the critical visual properties which give rise to this improved performance. The EFT is a search task and so here a radial frequency (RF) search task was created to directly explore efficacy of visual search and also the influence of element overlap on performance. In all conditions, the task was to detect whether the target RF3 (a triangular shape chosen for its visual properties) was present among a number of distracter RF4 (a square shape) patterns. The conditions employed were: 'singles', where all the patterns were spatially discrete, 'pairs', where two overlapping elements formed each cluster, and 'quads', comprising four overlapping elements per cluster. Compared to students scoring low on the Autism Spectrum Quotient (AQ; n=27), those scoring high on the AQ (n=23) were faster on the EFT and also significantly less influenced by increasing set size of the stimulus array in all RF search task conditions. However, the group difference in RF search performance was unaffected by the amount of stimulus overlap. Thus a simple search task is sufficient to detect a performance advantage associated with higher levels of autistic traits and has the advantages of a solid footing in visual theory and being readily repeatable for the purpose of assessing performance variability and change with interventions.
We aimed to examine the association between lifetime cannabis use and estimates of both premorbid... more We aimed to examine the association between lifetime cannabis use and estimates of both premorbid and current cognitive function in psychotic disorders in an Australian cohort. In an Australian multicenter cohort, 1237 participants with an established ICD-10 diagnosis of psychotic disorder were categorised according to history of lifetime cannabis use (non-users, n=354; cannabis users, n=221; cannabis dependency, n=662). Groups were analyzed according to available indices of cognitive ability: the National Adult Reading Test - Revised (NART-R) for ability prior to illness onset; and the Digit Symbol Coding Test (DSCT) for current ability. Two-way analysis of variance was conducted without any covariate, followed by a two-way analysis of covariance (using age, age at onset of psychiatric illness, premorbid IQ and the Socio-Economic Index for Areas (SEIFA) rankings). Whilst there appeared to be a significant association between cannabis use and mean DSCT (higher DSCT scores in cannabis using groups) F(2,1080)=9.478, p<0.001, η2=0.017), once covariates were used in the analysis there were no significant differences between groups in mean DSCT scores (F(2,1011)=0.929, p=0.395, η2=0.002). Similarly there were no differences between groups in mean NART scores once, age, age at illness onset and SEIFA rankings were used as covariates (F(2,1032)=1.617, p=0.199, η2=0.003). Confounding variables underpin the association between cannabis use and cognitive function in psychotic disorders. Taken together, it would appear that cannabis use or dependence has no additive effect on cognitive dysfunction in these disorders.
Background: In this study, we conducted a broad investigation of neuropsychological functioning i... more Background: In this study, we conducted a broad investigation of neuropsychological functioning in schizophrenia patients with first-rank (passivity) symptoms (FRS) using standardized cognitive tests. We focused on 3 neuropsychological domains, partly informed by 3 broad hypotheses concerning the pathogenesis of FRS. We tested predictions that patients with FRS would show: (i) memory deficits consistent with abnormalities in medial temporal lobe functioning; (ii) reduced cerebral lateralization on tasks of motor and language functions, and (iii) deficits on tasks of executive functions as a measure of the integrity of the prefrontal cortex for supporting self-monitoring processes. Sampling and Methods: In 2 parallel studies, we administered a range of neuropsychological tests to patients with FRS (sample A = 17, sample B = 15) and without FRS (sample A = 28, sample B = 20) and to healthy controls (sample A = 109, sample B = 22). Results: The results showed reduced cerebral lateralization in patients with FRS, but there were no memory deficits or executive dysfunctions relative to patients without FRS. An unexpected finding was that, on many cognitive tasks, the performance of the patients with FRS was relatively spared compared to that of the patients without FRS. These results could not be accounted for by demographic features or medication effects. Conclusions: Our results provide qualified support for the reduced lateralization hypothesis. Analyses of performance across neuropsychological domains showed that generalized deficit is not a sufficient explanation for the occurrence of FRS.
... Flavie AV Waters1''3" Johanna C. Badcock and Murray T. Maybery &am... more ... Flavie AV Waters1''3" Johanna C. Badcock and Murray T. Maybery 'School of Psychology and 2School of Psychiatry and Clinical Neurosciences, University of Western Australia; Centre for Clinical Research in Neuropsychiatry, Graylands Hospital, Perth; 4Neuroscience Institute ...
Journal of Nervous and Mental Disease, Dec 1, 2009
Memories of conversations are composed of what was said (speech content) and information about th... more Memories of conversations are composed of what was said (speech content) and information about the speaker's voice (speaker identity). In the current study, we examined whether patients with schizophrenia would show difficulties integrating speech content and speaker identity in memory, as measured in a gender-identity (male/female) recognition task. Forty-one patients and a comparison group of 20 healthy controls took part in the study. In contrast to controls, patients demonstrated greater impairments in memory for female, but not male, voices. These results are consistent with studies of speech perception that show that female voices have more complex "vocal" characteristics and require greater integration compared with male voices, and with the context memory hypothesis of schizophrenia which suggests that memory binding impairments may result in degraded or incomplete representations of memory traces as the task requirements become increasing complex.
The Embedded Figure Test (EFT) requires locating a simple shape embedded within a background of o... more The Embedded Figure Test (EFT) requires locating a simple shape embedded within a background of overlapping target-irrelevant scene elements. Observers with autism, or those with high levels of autistic-like traits, typically outperform matched comparison groups on the EFT. This research investigated the critical visual properties which give rise to this improved performance. The EFT is a search task and so here a radial frequency (RF) search task was created to directly explore efficacy of visual search and also the influence of element overlap on performance. In all conditions, the task was to detect whether the target RF3 (a triangular shape chosen for its visual properties) was present among a number of distracter RF4 (a square shape) patterns. The conditions employed were: 'singles', where all the patterns were spatially discrete, 'pairs', where two overlapping elements formed each cluster, and 'quads', comprising four overlapping elements per cluster. Compared to students scoring low on the Autism Spectrum Quotient (AQ; n=27), those scoring high on the AQ (n=23) were faster on the EFT and also significantly less influenced by increasing set size of the stimulus array in all RF search task conditions. However, the group difference in RF search performance was unaffected by the amount of stimulus overlap. Thus a simple search task is sufficient to detect a performance advantage associated with higher levels of autistic traits and has the advantages of a solid footing in visual theory and being readily repeatable for the purpose of assessing performance variability and change with interventions.
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