Biomedical subjects

Catherine M Diaz-Asper

Publications and source records attributed to Catherine M Diaz-Asper.

4 recordsLinked to original sources

PubMed2006

Neuropsychological functioning in bipolar disorder and schizophrenia.

BACKGROUND: Some patients with bipolar disorder (BD) demonstrate neuropsychological deficits even when stable. However, it remains unclear whether these differ qualitatively from those seen in schizophrenia (SZ). METHODS: We compared the nature and severity of cognitive deficits shown by 106 patients with SZ and 66 patients with BD to 316 healthy adults (NC). All participants completed a cognitive battery with 19 individual measures. After adjusting their test performance for age, sex, race, education, and estimated premorbid IQ, we derived regression-based T-scores for each measure and the six cognitive domains. RESULTS: Both patient groups performed significantly worse than NCs on most (BD) or all (SZ) cognitive tests and domains. The resulting effect sizes ranged from .37 to 1.32 (mean=.97) across tests for SZ patients and from .23 to .87 (mean=.59) for BD patients. The Pearson correlation of these effect sizes was .71 (p<.001). CONCLUSIONS: Patients with bipolar disorder suffer from cognitive deficits that are milder but qualitatively similar to those of patients with schizophrenia. These findings support the notion that schizophrenia and bipolar disorder show greater phenotypic similarity in terms of the nature than severity of their neuropsychological deficits.

Adult↗

PubMed2006

Catechol-O-methyltransferase polymorphisms and some implications for cognitive therapeutics.

Catechol-O-methyltransferase (COMT) is a gene involved in the degradation of dopamine and may both increase susceptibility to develop schizophrenia and affect neuronal functions involved in working memory. A common variant of the COMT gene (val(108/158)met) has been widely reported to affect pre-frontally mediated working memory function, with the high-activity val allele associated with poorest performance across a number of tests sensitive to updating and target detection. Pharmacological manipulations of COMT val(108/158)met also have reliably produced alterations in cognitive function, in line with an inverted U function of prefrontal dopamine signaling. Furthermore, there is accumulating evidence that COMT val(108/158)met genotype may influence the cognitive response to antipsychotic treatment in schizophrenia patients, with met allele load predicting the greatest improvement with medication. Recently, other single-nucleotide polymorphisms (SNPs) across the COMT gene have emerged as possible risk alleles for schizophrenia, although little is known about whether they affect prefrontal cognition in a manner similar to COMT val(108/158)met. Preliminary evidence suggests a modest role for a SNP in the 5' region of the gene on select tests of attention and target detection. Haplotype effects also may account for a modest percentage of the variance in test performance, and are an important area for future study.

Catechol O-Methyltransferase↗

PubMed2006

Spatial memory following temporal lobe resection.

The present study sought a clearer understanding of spatial memory function consequent to temporal lobe resection, and, in particular, of spatial memory function with respect to two- as well as three-dimensional frames of reference. Relative to a group of 15 control participants, a group of 15 epilepsy patients with right temporal resections demonstrated deficits of memory for locations in a two-dimensional display. A group of 13 epilepsy patients with left temporal resections did not demonstrate such deficits. The right and the left resection groups both demonstrated deficits of memory for item-location relationships in a two-dimensional display. The right but not the left resection group demonstrated deficits of memory for item-location relationships in a three-dimensional display. The differing results that were observed for item-location relationships in two- and three-dimensional displays were attributed to differences in the way item information is bound with location information concerning two- and three-dimensional domains.

Adult↗

PubMed2004

How well does IQ predict neuropsychological test performance in normal adults?

The strength and nature of the association between IQ and performance on other cognitive tests has both practical and conceptual significance for clinical neuropsychology. In this study, 28 measures derived from 16 cognitive tests were analyzed as a function of IQ in 221 adults. Participants were grouped by their IQ scores as having below average (BA), average (A), or above average (AA) intelligence. Planned comparisons revealed that A adults performed significantly better than BA adults on 25 of the 28 cognitive measures, and that AA adults performed significantly better than A adults on 19 of 28 measures. Effect sizes averaged.74 for BA-A comparisons and.41 for A-AA comparisons. Linear, quadratic, and cubic functions described the relationships between IQ and cognitive test performance equally well for most individual test measures and for a composite index of test performance, whereas quadratic and cubic functions explained the proportion of abnormal performances better than a linear function. These findings confirm that IQ predicts concurrent neuropsychological performance across the entire spectrum of intelligence, but more so among persons of average IQ or less than among those with above average IQ.

Adult↗