Exploration of the Raven APM-National Adult Reading Test discrepancy as a measure of intellectual decline in older persons.

Previous studies have shown that the discrepancy between performance on "fluid" and "crystallized" intelligence measures may serve as an indicator for intellectual decline. The validity of this procedure in older persons is unknown. The present study developed a multiple regression equation, to predict the Raven Advanced Progressive Matrices (APM) score from the National Adult Reading Test (NART) score and demographic variables in a large sample of healthy older persons (n = 270). The discrepancy between the predicted and observed Raven APM scores was transformed into a percentile distribution as an indicator of intellectual decline, which can be used in clinical practice. The validity of the procedure was further examined by comparing the proportion of persons with a significant decline (at the -1 and -1.65 SD level) between two older patient samples (87 patients with cerebral stroke and 387 patients with diabetes mellitus) by means of χ(2) tests. There was a significantly higher rate of intellectual decline at the -1 SD ("below average") and -1.65 SD ("impaired") cutoff levels for patients with stroke compared with patients with diabetes (stroke, 34% and 14%; diabetes, 16% and 5%, p < .05). These findings suggest that the Raven APM-NART discrepancy may be a useful measure of intellectual decline in older persons.

The Brixton Spatial Anticipation Test as a test for executive function: validity in patient groups and norms for older adults.

Impairments in executive functioning frequently occur after acquired brain damage, in psychiatric disorders, and in relation to aging. The Brixton Spatial Anticipation Test is a relatively new measure for assessing the ability to detect and follow a rule, an important aspect of executive functioning. To date, normative data on this task are limited, particularly concerning the elderly. This study presents age- and education-adjusted regression-based norms obtained in a group of healthy older participants (n = 283; mean age 67.4 +/- 8.5 years). The applicability and validity of these norms were further examined in different groups of patients with stroke (n = 106), diabetes mellitus (n = 376), MCI/early dementia (n = 70), psychiatric disorders (n = 63), and Korsakoff's syndrome (n = 41). The results showed that patients with Korsakoff's syndrome, stroke, and psychiatric disorders performed significantly worse than healthy controls. Test-retest correlation (n = 83), learning effects, and correlations with other neuropsychological tests were also explored. Based on the present study, the Brixton test appears a useful addition to existing measures of executive functioning. Moreover, the test can be reliably applied in different groups of clinical patients.

The backward span of the Corsi Block-Tapping Task and its association with the WAIS-III Digit Span.

The Corsi Block-Tapping Task measures visuospatial short-term and working memory, but a standardized backward condition is lacking. The authors present a standardized backward procedure that was examined in 246 healthy older adults (ages 50 to 92), comparing the results with the Digit Span subtest of the Wechsler Adult Intelligence Scale--Third Edition. Principal component analysis resulted in a two-factor model, dissociating a verbal and a spatial working-memory factor. Also the Corsi backward is not more difficult than the Corsi forward, in contrast to the Digit Span backward that is more difficult than the Digit Span forward. This may suggest that the Corsi Block-Tapping Task backward task relies on processing within working-memory's slave systems, whereas the Digit Span backward also relies on the central executive component of working memory. Finally, regression-based normative data and cutoff scores for older adults are presented for use in clinical practice.

Cognitive functioning and brain MRI in patients with type 1 and type 2 diabetes mellitus: a comparative study.

BACKGROUND/AIMS: Diabetes mellitus (DM) may affect the central nervous system, resulting in cognitive impairments. It has been suggested that cognitive impairments are more pronounced in DM2 than in DM1, but studies that directly compare the effects of these 2 types of DM on cognition are lacking. METHODS: Forty patients with DM1 (mean duration: 34 years) were compared with 40 age- and education-matched patients who were known to have DM2 (mean duration: 7 years). Extensive neuropsychological assessment focussed on abstract reasoning, memory, attention and executive function, visuoconstruction and information processing speed. Psychological well-being was measured and brain MRIs were obtained. RESULTS: No systematic between-group differences were observed in neuropsychological measures or levels of psychological well-being. DM2 patients showed significantly more deep white matter lesions and cortical atrophy on MRI (p < 0.01). CONCLUSION: DM1 patients with more than 30 years of DM have a similar cognitive profile and better MRI ratings than age- and education-matched DM2 patients with only 7 years of DM.

A detailed profile of cognitive dysfunction and its relation to psychological distress in patients with type 2 diabetes mellitus.

Type 2 diabetes mellitus (DM2) is a common metabolic disorder. DM2 is associated with cognitive impairments, and with depressive symptoms, which occur in about one third of patients. In the current study we compared the cognitive profile and psychological well-being of 119 patients with DM2 (mean age: 66 +/- 6; mean duration: 9 +/- 6 years) with 55 age and education matched-control participants. Groups were compared on cognitive performance in five major cognitive domains, psychological wellbeing [assessed by Symptom Checklist (SCL)-90-R and the Beck Depression Inventory (BDI-II)] and abnormalities on brain MRI. We hypothesized an interrelationship between cognition, MRI abnormalities, and psychological well-being. DM2 patients performed significantly worse than controls on cognitive tasks, especially on tasks that required more mental efficiency, although the differences were modest (effect sizes Cohen d < .6). We speculate that DM2 patients have a diminished ability to efficiently process unstructured information. Patients with DM2 had significantly higher scores on the SCL-90-R (p < .001) and on the BDI-II (p < .001) and worse MRI ratings than controls, but psychological distress did not correlate with cognition, MRI ratings or biomedical characteristics. Contrary to our hypothesis, cognitive disturbances and psychological distress thus seem independent symptoms of the same disease.

The modified Location Learning Test: norms for the assessment of spatial memory function in neuropsychological patients.

This study examines the applicability of the modified Location Learning Test (mLLT) as a test of spatial memory in neuropsychological patients. Three groups of participants were examined: stroke patients, patients with diabetes mellitus and healthy participants (N=411). Three error measures were computed, the Total Score (index of overall performance), the Learning Index (the learning curve over subsequent trials) and the Delayed Recall Score, measuring decay over time. The Learning Index was the most sensitive measure, showing differences between the three groups as well as lateralization effects within the stroke group. Also, the mLLT correlated significantly with the Rey Auditory Verbal Learning Test, as well as with age and education level. Regression-based normative data were computed based on the healthy participants. In all, the mLLT appears to be a sensitive and valid test for the detection of object-location memory impairments in clinical groups.

Cognitive performance, psychological well-being, and brain magnetic resonance imaging in older patients with type 1 diabetes.

Modest cognitive impairment has been reported in young-adult patients with type 1 diabetes. In older patients with type 2 diabetes, cognitive impairments are more pronounced, which might be due to age but also to differential effects of type 1 diabetes and type 2 diabetes on the brain. This study therefore assessed cognitive performance and magnetic resonance imaging (MRI) of the brain in older type 1 diabetic patients. Forty type 1 diabetic patients (age >50 years) and 40 age-matched control subjects were included. Neuropsychological assessment included all major cognitive domains, and psychological well-being was assessed with questionnaires. Atrophy, white-matter abnormalities, and infarcts were rated on MRI scans. Type 1 diabetic patients performed slightly (effect sizes <0.4) worse on cognitive tasks, but only "speed of information processing" reached statistical significance. No significant between-group differences were found on any of the MRI parameters. Type 1 diabetic patients tended to report more cognitive and depressive problems than control subjects, but this did not correlate with the performance on cognitive tests. We conclude that cognition in older type 1 diabetic patients is only mildly disturbed. Chronic exposure to hyperglycemia is in itself, even at older age, apparently not sufficient to have considerable impact on the brain.

Brain magnetic resonance imaging correlates of impaired cognition in patients with type 2 diabetes.

The structural correlates of impaired cognition in type 2 diabetes are unclear. The present study compared cognition and brain magnetic resonance imaging (MRI) between type 2 diabetic patients and nondiabetic control subjects and assessed the relationship between cognition and MRI findings and blood pressure and metabolic control. The study included 113 patients and 51 control subjects. Brain MRI scans were rated for white matter lesions (WMLs), cortical and subcortical atrophy, and infarcts. Neuropsychological test scores were divided into five cognitive domains and expressed as standardized Z values. Type 2 diabetes was associated with deep WMLs (P = 0.02), cortical (P < 0.001) and subcortical (P < 0.05) atrophy, (silent) infarcts (P = 0.06), and impaired cognitive performance (attention and executive function, information-processing speed, and memory, all P < 0.05). Adjustment for hypertension did not affect the results. Within the type 2 diabetic group, cognitive function was inversely related with WMLs, atrophy, and the presence of infarcts (adjusted for age, sex, and estimated IQ), and there was a modest association with HbA1c and diabetes duration. This association was strongest for age, even more so than in control subjects. We conclude that cognitive impairments in patients with type 2 diabetes are not only associated with subcortical ischemic changes in the brain, but also with increased brain atrophy.

The effects of type 1 diabetes on cognitive performance: a meta-analysis.

OBJECTIVE: To investigate the exact nature and magnitude of cognitive impairments in patients with type 1 diabetes and the possible association with other disease variables, such as recurrent episodes of hypoglycemia and metabolic control. RESEARCH DESIGN AND METHODS: MedLine and PsycLit search engines were used to identify studies on cognitive performance in patients with type 1 diabetes. Effect sizes (Cohen's d), which are the standardized differences between the experimental and the control group, were calculated. In the meta-analysis, a combined d value was calculated, expressing the magnitude of associations across studies. RESULTS: A total of 33 studies were identified that met the inclusion criteria. Compared with nondiabetic control subjects, the type 1 diabetic group demonstrated a significantly lowered performance on the following cognitive domains: intelligence (d = -0.7), speed of information processing (d = -0.3), psychomotor efficiency (d = -0.6), visual (d = -0.4) and sustained attention (d = -0.3), cognitive flexibility (d = -0.5), and visual perception (d = -0.4). Lowered cognitive performance in diabetic patients appeared to be associated with the presence of microvascular complications but not with the occurrence of severe hypoglycemic episodes or with poor metabolic control. CONCLUSIONS: In patients with type 1 diabetes, cognitive dysfunction is characterized by a slowing of mental speed and a diminished mental flexibility, whereas learning and memory are spared.The magnitude of the cognitive deficits is mild to moderate, but even mild forms of cognitive dysfunction might hamper everyday activities since they can be expected to present problems in more demanding situations.

Cerebral dysfunction in type 1 diabetes: effects of insulin, vascular risk factors and blood-glucose levels.

Type 1 diabetes can lead to several well-described complications such as retinopathy, nephropathy and peripheral neuropathy. Evidence is accumulating that it is also associated with gradually developing end-organ damage in the central nervous system. This relatively unknown complication can be referred to as "diabetic encephalopathy" and is characterised by electrophysiological and neuroradiological changes, such as delayed latencies of evoked potentials, modest cerebral atrophy and (periventricular) white matter lesions. Furthermore, individuals with type 1 diabetes may show performance deficits in a wide range of cognitive domains. The exact mechanisms underlying this diabetic encephalopathy are only partially known. Chronic metabolic and vascular changes appear to play an important role. Interestingly, the differences in the "cognitive profile" between type 1 and type 2 diabetes also suggest a critical role for disturbances of insulin action in the central nervous system.