Mw Mansfield

Impairments in glucose tolerance can have a negative impact on cognitive function: A systematic research review

There is an increasing body of research investigating whether abnormal glucose tolerance is associated with cognitive impairments, the evidence from which is equivocal. A systematic search of the literature identified twenty-three studies which assessed either clinically defined impaired glucose tolerance (IGT) or variance in glucose tolerance within the clinically defined normal range (NGT). The findings suggest that poor glucose tolerance is associated with cognitive impairments, with decrements in verbal memory being most prevalent. However, the evidence for decrements in other domains was weak. The NGT studies report a stronger glucose tolerance-cognition association than the IGT studies, which is likely to be due to the greater number of glucose tolerance parameters and the more sensitive cognitive tests in the NGT studies compared to the IGT studies. It is also speculated that the negative cognitive impact of abnormalities in glucose tolerance increases with age, and that glucose consumption is most beneficial to individuals with poor glucose tolerance compared to individuals with normal glucose tolerance. The role of potential mechanisms are discussed.

Evidence for a second meal cognitive effect: glycaemic responses to high and low glycaemic index evening meals are associated with cognition the following morning

Abstract Low glycaemic index (GI) foods consumed at breakfast can enhance memory in comparison to high-GI foods; however, the impact of evening meal GI manipulations on cognition the following morning remains unexplored. Fourteen healthy males consumed a high-GI evening meal or a low-GI evening meal in a counterbalanced order on two separate evenings. Memory and attention were assessed before and after a high-GI breakfast the following morning. The high-GI evening meal elicited significantly higher evening glycaemic responses than the low-GI evening meal. Verbal recall was better the morning following the high-GI evening meal compared to after the low-GI evening meal. In summary, the GI of the evening meal was associated with memory performance the next day, suggesting a second meal cognitive effect. The present findings imply that an overnight fast may not be sufficient to control for previous nutritional consumption.

Acute glycaemic load breakfast manipulations do not attenuate cognitive impairments in adults with type 2 diabetes

BACKGROUND & AIMS Research on young healthy samples suggests that low glycaemic load foods can confer benefits for cognitive performance. The aim was to examine the effects of type 2 diabetes on cognitive function, and to investigate whether consumption of low glycaemic load breakfasts affects cognitive function in adults with type 2 diabetes. METHOD Memory, psychomotor skill and executive function were examined at two morning test sessions in 24 adults with type 2 diabetes and 10 adults with normal glucose tolerance (NGT) aged 45-77 years without dementia after water, low, and high glycaemic load breakfasts were consumed in accordance with a crossover, counterbalanced design. The type 2 diabetes and NGT groups were matched for education, depression, and IQ. RESULTS Type 2 diabetes was associated with impairments in verbal memory, spatial memory, psychomotor skill, and executive function compared to adults with NGT. Consumption of the three breakfast conditions did not impact on cognitive performance in the type 2 diabetes or NGT participants. CONCLUSIONS Abnormalities in glucose tolerance such as type 2 diabetes can have demonstrable negative effects on a range of cognitive functions. However, there was no evidence that low GL breakfasts administered acutely could confer benefits for cognitive function (ClincalTrials.gov identifier, NCT01047813).

Correspondence of continuous interstitial glucose measurement against arterialised and capillary glucose following an oral glucose tolerance test in healthy volunteers.

The aim of the present study was to validate the Glucoday continuous interstitial ambulatory glucose-monitoring device (AGD) against plasma glucose measured from arterialised venous (AV) and glucose from capillary whole blood (finger prick, FP) in non-diabetic subjects in response to an oral glucose tolerance test. Fifteen healthy overweight men (age 30-49 years, BMI 26-31 kg/m2) participated. Glucose levels were measured before, during and after consumption of an oral 75 g glucose load using twelve FP samples and forty-four 1 ml AV blood samples during 180 min. Interstitial glucose was measured via the AGD. Three venous samples for fasting insulin were taken to estimate insulin resistance. Profiles of AGD, AV and FP glucose were generated for each participant. Glucose values for each minute of the measurement period were interpolated using a locally weighted scatterplot smoother. Data were compared using Bland-Altman plots that showed good correspondence between all pairs of measurements. Concordance between the three methods was 0.8771 (Kendalls W, n 15, P < 0.001). Concordance was greater between AV and FP (W = 0.9696) than AGD and AV (W = 0.8770) or AGD and FP (W = 0.8764). Analysis of time to peak glucose indicated that AGD measures lagged approximately 15 min behind FP and AV measures. Percent body fat was significantly correlated with time to peak glucose levels for each measure, while BMI and estimated insulin resistance (homeostatic model assessment, HOMA) were not. In conclusion, AGD shows good correspondence with FP and AV glucose measures in response to a glucose load with a 15 min time lag. Taking this into account, AGD has potential application in nutrition and behaviour studies.

Type 2 diabetes and impaired glucose tolerance are associated with word memory source monitoring recollection deficits but not simple recognition familiarity deficits following water, low glycaemic load, and high glycaemic load breakfasts.

BACKGROUND It has been established that type 2 diabetes, and to some extent, impaired glucose tolerance (IGT), are associated with general neuropsychological impairments in episodic memory. However, the effect of abnormalities in glucose metabolism on specific retrieval processes such as source monitoring has not been investigated. The primary aim was to investigate the impact of type 2 diabetes and IGT on simple word recognition (familiarity) and complex source monitoring (recollection). A secondary aim was to examine the effect of acute breakfast glycaemic load manipulations on episodic memory. METHOD Data are presented from two separate studies; (i) 24 adults with type 2 diabetes and 12 controls aged 45-75years, (ii) 18 females with IGT and 47 female controls aged 30-50years. Controls were matched for age, IQ, BMI, waist circumference, and depression. Recognition of previously learned words and memory for specifically which list a previously learned word had appeared in (source monitoring) was examined at two test sessions during the morning after consumption of low glycaemic load, high glycaemic load and water breakfasts according to a counterbalanced, crossover design. RESULTS Type 2 diabetes (p<0.05) and IGT (p<0.01) were associated with significant source monitoring recollection deficits but not impairments in familiarity. Impairments were only observed in the late postprandial stage at the second test session. These impairments were not attenuated by the breakfast glycaemic load manipulations. CONCLUSIONS Isolated source monitoring recollection deficits indicate that abnormalities in glucose metabolism are not detrimental for global episodic memory processes. This enhances our understanding of how metabolic disorders are associated with memory impairments.

A low glycaemic load breakfast can attenuate cognitive impairments observed in middle aged obese females with impaired glucose tolerance

BACKGROUND AND AIMS There has been no systematic investigation of the individual and combined effects of impaired glucose tolerance (IGT) and obesity on cognitive function in the absence of ageing. The aims were to examine the effects of IGT and increased waist circumference on cognitive function in ostensibly healthy adults, and to investigate whether a low glycaemic load (GL) breakfast can attenuate cognitive impairments in these populations. METHODS AND RESULTS Sixty five females aged 30-50 years were classified into one of four groups following waist circumference (WC) measurements and an oral glucose tolerance test: NGT/low WC (n = 25), NGT/high WC (n = 22), IGT/low WC (n = 9), IGT/high WC (n = 9). Memory, psychomotor and executive functions were examined 30 and 120 min after consuming low GL, high GL and water breakfasts according to a randomised, crossover, counterbalanced design. IGT was associated with impairment of verbal and spatial memory, and psychomotor function relative to females with NGT, independent of waist circumference. Increased waist circumference was associated with impairment of verbal memory and executive function relative to females with low WC, independent of IGT. Consumption of the LGL breakfast attenuated verbal memory impairment in the IGT/high WC group relative to the HGL breakfast and no energy control. CONCLUSION Increased central adiposity and abnormalities in glucose tolerance preceding type 2 diabetes can have demonstrable negative effects on cognitive function, even in ostensibly healthy, middle-aged females. The potential for GL manipulations to modulate glycaemic response and cognitive function in type 2 diabetes and obesity merits further investigation.

S54 Cognitive function in adults with and without cystic fibrosis related diabetes (CFRD) attending a large UK cystic fibrosis unit

Introduction and objectives On reaching adulthood many cystic fibrosis (CF) sufferers develop cystic fibrosis related diabetes (CFRD). CFRD shares clinical characteristics with type 1 (T1DM) and type 2 diabetes mellitus (T2DM). Impaired glucose tolerance (IGT), T1DM and T2DM have deleterious effects on cognitive performance. Hence, patients with CFRD are hypothesised to show similar impairment. This study aimed to elucidate the nature and severity of any cognitive impairment in patients with CFRD compared to non-diabetic patients with CF and healthy controls matched as closely as possible for age, gender and education level. Patients with CF were also matched as closely as possible on CFTR genotype. Methods Adult (>16 years old), pancreatic insufficient patients registered to a large UK CF unit who had adequate verbal and written English were eligible. 49 patients with insulin-treated CFRD and 49 CF non-diabetics who had received a normal oral glucose tolerance test (OGTT) within the past 12 months were recruited. 46 healthy matched controls were recruited from relatives of patients and the general population. Cognitive performance was assessed using the Cambridge Neuropsychological Test Automated Battery (CANTAB). Subjective measures of sleep, stress, mood and cognitive functioning were also collected. Results Matched controls performed better than both groups of patients with CF on tests of visual memory and learning, verbal memory, visual sustained attention, processing speed and executive function. Patients with CFRD performed significantly worse than controls on tests of mental flexibility and processing speed, which is consistent with the pattern of impairment shown in T1DM, and on verbal memory and learning, which is consistent with the pattern of impairment shown in T2DM. Compared to non-diabetic patients with CF, those with CFRD performed worse on tests of visual sustained attention, verbal memory, working memory, and processing speed. Conclusion CFRD has a negative impact on cognitive performance akin to T1DM and T2DM. Non-diabetic patients with CF also show impaired cognition but to a lesser degree than CFRD. Even modest cognitive impairment in adults with CF may impact upon their self-management skills, health and quality of life.

295 Cognition in adult patients with cystic fibrosis (CF) with and without cystic fibrosis related diabetes (CFRD)

Objectives Impaired glucose tolerance (IGT), type 1 (T1DM) and type 2 diabetes mellitus (T2DM) have deleterious effects on cognitive performance. Hence, patients with cystic fibrosis related diabetes (CFRD) are hypothesized to show similar impairment. This study aimed to elucidate the nature and severity of any cognitive impairment in patients with CFRD compared to non-diabetic patients with CF and healthy controls matched as closely as possible for age, gender and education level. Patients with CF were also matched as closely as possible on CFTR genotype. Methods Adult (>16 years old), pancreatic insufficient patients registered to the Leeds CF Unit who had adequate verbal and written English were eligible. To date, 45 patients with insulin-treated CFRD and 47 non-diabetics who had received a normal oral glucose tolerance test (OGTT) within the past 12 months were included. 10 healthy controls were recruited to date from relatives of patients and the general population. Cognitive performance was assessed using the Cambridge Neuropsychological Test Automated Battery (CANTAB). Results Preliminary findings show that matched controls perform better than both groups of patients with CF on tests of visual memory and learning, verbal memory, visual sustained attention and executive function. Patients with CFRD performed worse than controls on tests of mental flexibility and visual sustained attention, which is consistent with the pattern of impairment shown in T1DM, and on verbal memory, which is consistent with the pattern of impairment shown in T2DM. Conclusion Like T1DM and T2DM, CFRD may have a negative impact on cognitive performance and needs to be explored.