Biomedical subjects

B E Snitz

Publications and source records attributed to B E Snitz.

5 recordsLinked to original sources

PubMed2000

PPVT-R as an estimate of premorbid intelligence in older adults.

The Peabody Picture Vocabulary Test-Revised (PPVT-R) was examined as an estimate of premorbid intelligence in a clinical sample of elderly patients (N = 150) undergoing clinical neuropsychological evaluation. PPVT-R standard scores were compared across grossly cognitively intact, mildly/moderately and severely impaired groups of patients, and compared to a short form of the Wechsler Adult Intelligence Scale-Revised (WAIS-R) and the Barona regression equation. Results indicate that, while the PPVT-R is vulnerable to increasing levels of cognitive impairment among patients with fewer years of education, the PPVT-R is stable across mild to moderate levels of impairment for patients with greater than 12 years of education. In a sub-sample of grossly cognitively intact patients (n = 91), the PPVT-R standard score correlated significantly with estimated WAIS-R FSIQ (r =.61). Compared to the Barona equation, the PPVT-R was less likely to over-estimate WAIS-R FSIQ in the grossly cognitively intact patients. These data suggest the PPVT-R to be a useful estimate of premorbid ability for patients with a greater than high-school education.

Adult↗

PubMed2000

Clinical versus mechanical prediction: a meta-analysis.

The process of making judgments and decisions requires a method for combining data. To compare the accuracy of clinical and mechanical (formal, statistical) data-combination techniques, we performed a meta-analysis on studies of human health and behavior. On average, mechanical-prediction techniques were about 10% more accurate than clinical predictions. Depending on the specific analysis, mechanical prediction substantially outperformed clinical prediction in 33%-47% of studies examined. Although clinical predictions were often as accurate as mechanical predictions, in only a few studies (6%-16%) were they substantially more accurate. Superiority for mechanical-prediction techniques was consistent, regardless of the judgment task, type of judges, judges' amounts of experience, or the types of data being combined. Clinical predictions performed relatively less well when predictors included clinical interview data. These data indicate that mechanical predictions of human behaviors are equal or superior to clinical prediction methods for a wide range of circumstances.

Decision Making, Computer-Assisted↗

PubMed1999

Neuropsychological and oculomotor correlates of spatial working memory performance in schizophrenia patients and controls.

Recent reports of spatial working memory deficits in schizophrenia provide evidence for dorsolateral prefrontal cortical (DLPFC) dysfunction. However, the question of how spatial working memory performance relates to other task impairments in schizophrenia considered reflective of frontal dysfunction, such as the Wisconsin Card Sorting Test (WCST) and smooth pursuit eye tracking, has been largely unexplored. Spatial working memory, as measured by a computerized visual-manual delayed response task (DRT), was evaluated in 42 schizophrenia patients and 54 normal controls. Subjects also completed a battery of neuropsychological and oculomotor tasks. Schizophrenia patients performed as accurately as controls on a no-delay, sensory-motor control condition, but showed a significant impairment in spatial accuracy with the addition of an 8-s delay and verbal distraction task. For the patients, working memory impairment was associated with fewer categories on the WCST, impaired eye tracking, fewer words learned on the Rey Auditory Verbal Learning Test, but not with measures of general cognitive and clinical functioning. Results suggest the presence of a sub-group of schizophrenia patients with common pathophysiology that accounts for the co-variance of several tasks implicating prefrontal dysfunction.

Adult↗

PubMed1996

Efficacy of the Continuous Visual Memory Test in lateralizing temporal lobe dysfunction in chronic complex-partial epilepsy.

The Continuous Visual Memory Test (CVMT) was hypothesized to measure nondominant temporal lobe dysfunction in patients with refractory complex-partial epilepsy. Thirty-seven temporal lobectomy candidates, of whom 20 had a right temporal seizure focus (RT) and 17 had a left temporal seizure focus (LT), were selected for study. Contrary to the hypothesis, initial results indicated that the LT group performed below the RT group for both the CVMT Total score and the Delayed Recognition score; however, group differences disappeared after accounting for Full Scale IQ scores. Both CVMT scores correlated positively and significantly with Full Scale IQ, Block Design, and the Meier Visual Discrimination Test, suggesting that overall cognitive functioning and visual-perceptual processing are positively related to CVMT performance. These results are consistent with other recent findings which suggest that extant nonverbal memory tests may be inadequate in lateralizing nondominant hemisphere lesions in complex-partial epilepsy.

Adolescent↗

PubMed1995

The D5 dopamine receptor gene in schizophrenia: identification of a nonsense change and multiple missense changes but lack of association with disease.

To determine whether mutations in the D5 dopamine receptor gene (DRD5) are associated with schizophrenia, the gene was examined in 78 unrelated schizophrenic individuals (156 DRD5 alleles). After amplification by the polymerase chain reaction, products were examined by dideoxy fingerprinting (ddF), a screening method related to single strand conformational polymorphism analysis that detects essentially 100% of mutations. All samples with abnormal ddF patterns were sequenced. Nine different sequence changes were identified. Five of these were sequence changes that would result in protein alterations; of these, one was a nonsense change (C335X), one was a missense change in an amino acid conserved in all dopamine receptors (N351D), two were missense changes in amino acids that are identical in only some dopamine receptors and in only some species (A269V; S453C), and one was a missense change in a non-conserved amino acid (P330Q). To investigate whether the nonsense change (C335X), predicted to prematurely truncate the receptor protein and result in a 50% diminution of functional protein, was associated with schizophrenia, other neuropsychiatric diseases, or specific neuropsychological, psychophysiological, or personality traits, both case-control and family analyses were performed. No statistically-significant associations were detected with schizophrenia or other neuropsychiatric disease. There also were no significant associations between any one measure of neuropsychological function. However, a post-hoc analysis of combined measures of frontal lobe function hinted that heterozygotes for C335X may have a vulnerability to mild impairment, but these findings must be interpreted with caution.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗