Biomedical subjects

Michèle Gagnon

Publications and source records attributed to Michèle Gagnon.

8 recordsLinked to original sources

PubMed2006

Exploratory factor analysis of neuropsychological tests and their relationship to the Brown-Peterson task.

The interference condition of the Brown-Peterson task and the auditory consonant trigrams test was designed to evaluate working memory in that it required a division of attentional processes to complete two cognitive tasks. However, the specific cognitive functions contributing to the performance of this interference task have yet to be determined. The objective of this study was to determine what other tasks are comparable to the Brown-Peterson task and conduct an exploratory factor analysis that included the measures from the Brown-Peterson task and other neuropsychological measures. A neuropsychological battery was administered to younger participants (n=107, mean age=20.83) and older participants (n=93, mean age=70.14). Factor analysis yielded a two-factor solution. Performance after the intervening serial subtraction task loaded on an auditory/visual working memory and complex attention factor and had common loadings with working memory subtests of the WAIS-III and the spatial span subtest of the WMS-III. Results suggest that the performance after the intervening serial subtraction task evaluates dual information processing, complex attention, and working memory.

Adolescent↗

PubMed2004

Explicit and objective scoring criteria for the taylor complex figure test.

The Rey and Taylor figures are two constructional and visual memory tests used interchangeably. The purpose of this study was to develop a scoring system for the Taylor figure based on the explicit guidelines established by Meyers and Meyers (1995) for the Rey figure. Younger (n = 97; mean age = 21 years) and older (n = 61; mean age = 72 years) participants' performance on the Taylor figure was scored according to the proposed scoring system and the original scoring system devised by Taylor (1989). Both scoring systems yielded comparable scores on the Taylor figure as well as comparable patterns of validity and good interrater reliabilities (0.85-0.98). Although the present system does not further improve scoring reliability, it renders both tests similar in methodology and simplifies training to evaluate the two figures. The present study also reveals the limitations of the use of the Taylor and the Rey in test-retest situations but suggests that administering the Taylor first would improve the comparability of the two figures in a test-retest situation.

Adult↗

PubMed2004

The relationship between impaired glucose tolerance, type 2 diabetes, and cognitive function.

The present review integrates findings of published studies that have evaluated the cognitive function of treated and untreated type 2 diabetic patients and provides a detailed overview of the neuropsychological assessments conducted. Cognitive deficits are observed in older people with glucose intolerance or untreated diabetes but these deficits appear to be attenuated by treatments that improve glycemic control. Cognitive decrements in treated type 2 diabetic patients are most consistently observed on measures of verbal memory (35% of the measures) and processing speed (45% of the measures) while preserved function is observed on measures of visuospatial, attention, semantic and language function. Some studies suggest that deficits in cognitive functions are associated with poorer glycemic control. A number of other factors, such as depression, cardiovascular and cerebrovascular disease, increase these deficits. We conclude that, in diabetic patients who achieve and maintain good glycemic control, type 2 diabetes only has a small impact on cognitive functions before the age of 70 years. However, early onset of type 2 diabetes, poor glycemic control and the presence of micro- and macrovascular disease may interact to produce early cognitive deficits. In older adults (70 years and over), diabetes likely interacts with other dementing processes such as vascular disease and Alzheimer's disease to hasten cognitive decline.

Cognition↗

PubMed2004

The relationships between atherosclerosis, heart disease, type 2 diabetes and dementia.

Type 2 diabetes in the elderly is associated with increased incidence of vascular disease, particularly, atherosclerosis of large blood vessels. Together with other risk factors such as dyslipidemia, atherosclerosis increases the risk for coronary heart disease and stroke. Most studies that have examined the impact of type 2 diabetes and other heart disease risk factors on cognitive functions do not provide evidence that heart disease risk factors (with the possible exception of triglycerides) further increase the likelihood of observing cognitive deficits in diabetic patients. However, none of these studies used imaging techniques to evaluate atherosclerosis or evidence of cerebrovascular disease, such as infarctions. The few studies that have included brain imaging suggest that evidence of cerebrovascular disease further increases the risk for dementia in diabetic patients. The results of longitudinal studies suggest that diabetes is an independent risk factor for cognitive decline and dementia. The pattern of neuropsychological performance observed in type 2 diabetic patients appears to be the result of multiple interacting processes developing over time. In addition to the detrimental effects of protracted impaired glucose regulation on the central nervous system, type 2 diabetes pathology also encompasses the detrimental effects of associated complications such as cerebrovascular disease, which is likely the main cause of the observed processing speed/reaction time decrements.

Causality↗

PubMed2004

Addressing the differences in speed of processing of the intervening calculation task on the modified Brown-Peterson task.

The Modified Brown-Peterson task (MBPT) is a task of divided attention and working memory that requires central executive functioning. It is a variant of the Brown-Peterson technique and is useful for studying short-term retention of information. It involves the recall of auditory information under conditions of interference (i.e., counting backwards). Previous research has not addressed the effect of individual differences in processing speed for the intervening calculations. In a sample of 81 young participants, we determined whether the number of correct calculations performed is related to recall performance on the MBPT. Results indicated that the number of calculations performed was not significantly related to the recall performance on the MBPT. Rather, the number of correct calculations performed during the interference task of the MBPT was associated with arithmetic ability as measured by the arithmetic subtest of the Adult Intelligence Scale-III (Wechsler, 1997). These results suggest that the subtractions in the MBPT create interference regardless of mathematical ability or speed at which the subtractions are performed during the interference condition of the MBPT task. This observation suggests that the results on this test are independent of mathematical ability and represent a useful measure of working memory.

Adult↗

PubMed2003

Effect of age and glucoregulation on cognitive performance.

Non-insulin dependent diabetes mellitus (NIDDM) has been associated with a number of physiological consequences including neuropathy, retinopathy and incidence of vascular disease. Recently, several authors reviewed studies that suggested that NIDDM is associated with cognitive impairments leading to a higher incidence of dementia. In the present experiment, we measured cognitive function in 57 healthy male and female non-diabetic older participants who ranged in age from 55 to 84. Various biological measures were obtained including a glucose tolerance test during which glucose and insulin were measured. Participants were separated into better and poorer glucoregulatory groups on the basis of their blood glucose levels during the tolerance test. Participants were evaluated twice, once after drinking a saccharin solution and on another occasion after drinking a glucose solution (50 g). Older participants (72 years and over) with poorer glucoregulation had the worse performance in tests evaluating working memory, verbal declarative memory and executive functions. Glucose administration appeared to only attenuate the decrements observed in the saccharin condition in the older participants for some of the tests. These results suggest that cognitive functions may be impaired before glucoregulatory impairment reaches levels consistent with a type II diabetes diagnosis.

Age Factors↗

PubMed2003

Comparing the Rey and Taylor complex figures: a test-retest study in young and older adults.

The Rey and Taylor figures, two visual perception and memory tests, are not equivalent in terms of their difficulty. The purpose of this study was to examine factors such as age, gender, order of administration, copy time, and copy score that could account for the variability in recall performance. Copy score was shown to be the best overall predictor of recall. Younger participants recalled more units than older participants on both complex figures. Furthermore, older participants appeared to benefit more from the presentation of the Taylor figure first compared to when they were presented with the Rey figure first. The present findings reveal the importance of test order and provide equations that can be used to facilitate the comparison of scores derived from the two figures in test-retest situations.

Adult↗

PubMed2002

Impact of peripheral glucoregulation on memory.

Impaired glucoregulation is associated with neuropsychological deficits, particularly for tests that measure verbal declarative memory performance in older diabetic patients. The performances of 74 undergraduate students (mean age = 21 years) on several verbal declarative measures, including immediate and delayed paragraph recall, verbal free recall, and order reconstruction tasks, were correlated with glucoregulatory indices. The indices were obtained from glucose and insulin levels after a 75-g glucose load. In general, higher blood glucose levels were associated with poorer performance on all memory tests. Glucose ingestion did not interact with performance except on the most difficult task. Subjects with poorer glucoregulation showed higher evoked glucose and insulin, suggestive of a mild glucose intolerance accompanied by mild insulin insensitivity. Results suggest that poor peripheral glucoregulation has an impact on central nervous system functions.

Adult↗