Vitamin B12 and Folate Status in Cognitively Healthy Older Adults and Associations with Cognitive Performance.

OBJECTIVES: To determine prevalence of vitamin B12 and folate deficiency and associations with cognitive performance in participants recruited for the Cognitive Health in Ageing Register: Investigational, Observational, and Trial Studies in Dementia Research: Prospective Readiness cOhort Study (CHARIOTPRO) SubStudy (CPRO-SS). DESIGN: Cross-sectional analysis of data collected in the screening phase for the CPRO-SS. SETTING: Participants were recruited from the Chariot Register at Imperial College London comprising approximately 39,000 community dwelling volunteers. PARTICIPANTS: Community dwelling individuals aged 60-85 years with B vitamin biomarker measures available were included (n=1946). After medical history and other exclusions, 1347 cognitively healthy participants were included for analysis of cognitive data. MEASUREMENTS: Cognitive status was assessed with the Repeatable Battery for Neuropsychological Status (RBANS). Assays included vitamin B12 and folate, followed by serum methylmalonic acid and homocysteine levels for those with low vitamin B12. Gender-specific linear regression analysis was performed for associations between cognition and biomarkers. Non-gender specific regression for groups graded by B vitamin deficiency severity were also performed. RESULTS: Vitamin B12 deficiency (<148pmol/L) was found in 17.2% of individuals and folate deficiency (<10nmol/L) in 1% of our participants. Low vitamin B12 was associated with poorer memory (p<0.03) in men. A high BMI predicted poorer attention and visuospatial indices (p<0.05). A regression analysis by B12 level revealed associations with poorer attention (ß -6.46; p=0.004) for the deficient group and with immediate memory (ß -2.99; p=0.019) for those categorised as severely deficient. CONCLUSION: Older men and women are prone to vitamin B12 deficiency with associated subtle and different domain-specific disruptive effects in measures of memory and attention. Elevated homocysteine and methylmalonic acid contributed to poorer cognitive performance. Novel groups at particular risk of cognitive deficit were identified for future interventional studies in this field.

Differences in cognitive profile between TIA, stroke and elderly memory research subjects: a comparison of the MMSE and MoCA.

BACKGROUND: The Montreal Cognitive Assessment (MoCA) appears more sensitive to mild cognitive impairment (MCI) than the Mini-Mental State Examination (MMSE): over 50% of TIA and stroke patients with an MMSE score of ≥27 ('normal' cognitive function) at ≥6 months after index event, score <26 on the MoCA, a cutoff which has good sensitivity and specificity for MCI in this population. We hypothesized that sensitivity of the MoCA to MCI might in part be due to detection of different patterns of cognitive domain impairment. We therefore compared performance on the MMSE and MoCA in subjects without major cognitive impairment (MMSE score of ≥24) with differing clinical characteristics: a TIA and stroke cohort in which frontal/executive deficits were expected to be prevalent and a memory research cohort. METHODS: The MMSE and MoCA were done on consecutive patients with TIA or stroke in a population-based study (Oxford Vascular Study) 6 months or more after the index event and on consecutive subjects enrolled in a memory research cohort (the Oxford Project to Investigate Memory and Ageing). Patients with moderate-to-severe cognitive impairment (MMSE score of <24), dysphasia or inability to use the dominant arm were excluded. RESULTS: Of 207 stroke patients (mean age ± SD: 72 ± 11.5 years, 54% male), 156 TIA patients (mean age 71 ± 12.1 years, 53% male) and 107 memory research subjects (mean age 76 ± 6.6 years, 46% male), stroke patients had the lowest mean ± SD cognitive scores (MMSE score of 27.7 ± 1.84 and MoCA score of 22.9 ± 3.6), whereas TIA (MMSE score of 28.4 ± 1.7 and MoCA score of 24.9 ± 3.3) and memory subject scores (MMSE score of 28.5 ± 1.7 and MoCA score of 25.5 ± 3.0) were more similar. Rates of MoCA score of <26 in subjects with normal MMSE ( ≥27) were lowest in memory subjects, intermediate in TIA and highest after stroke (34 vs. 48 vs. 67%, p < 0.001). The cerebrovascular patients scored lower than the memory subjects on all MoCA frontal/executive subtests with differences being most marked in visuoexecutive function, verbal fluency and sustained attention (all p < 0.0001) and in stroke versus TIA (after adjustment for age and education). Stroke patients performed worse than TIA patients only on MMSE orientation in contrast to 6/10 subtests of the MoCA. Results were similar after restricting analyses to those with an MMSE score of ≥27. CONCLUSIONS: The MoCA demonstrated more differences in cognitive profile between TIA, stroke and memory research subjects without major cognitive impairment than the MMSE. The MoCA showed between-group differences even in those with normal MMSE and would thus appear to be a useful brief tool to assess cognition in those with MCI, particularly where the ceiling effect of the MMSE is problematic.

APOE alleles predict the rate of cognitive decline in Alzheimer disease: a nonlinear model.

BACKGROUND: The APOE genotype predicts the age at onset of Alzheimer disease (AD) and neuropathologic progression. However, studies relating APOE alleles to the rate of cognitive decline have been inconclusive. This may stem from their use of linear statistical analyses. OBJECTIVE: To model relations of APOE alleles to the rate of cognitive decline in AD, nonlinearly. METHODS: Serial measures of cognitive ability were obtained using the cognitive scale of the Cambridge Examination for Mental Disorders of the Elderly in 218 patients with AD. The relations of these serial scores to APOE alleles were tested using nonlinear and linear mixed-effects models. RESULTS: In the non-linear model, possession of an APOE epsilon4 allele related to earlier and faster cognitive decline, but possession of an APOE epsilon2 related to slower decline. Patients homozygous for APOE epsilon4 showed faster cognitive decline than heterozygotes. The linear model was less sensitive and did not detect differences between APOE epsilon4 homo- and heterozygotes. CONCLUSIONS: APOE genotype strongly predicts the rate of cognitive decline in Alzheimer disease. The decline shows a dose-response relation with the APOE epsilon4 allele, but the APOE epsilon2 allele is protective. The nonlinear model yielded larger estimates of the maximal rate of decline than the linear.

Sensitivity and specificity of neuropsychological tests for mild cognitive impairment, vascular cognitive impairment and Alzheimer's disease.

BACKGROUND: Early diagnosis of dementia is important for those who might benefit from treatment. We designed a brief comprehensive neuropsychological test battery to help differentiate control subjects from patients with mild cognitive impairment (MCI) and dementia. METHOD: The battery included tests of memory, attention, executive function, speed, perception and visuospatial skills. It was administered to subjects from the OPTIMA cohort: 51 controls, 29 with MCI, 60 with 'possible' or 'probable' Alzheimer's disease (AD) (NINCDS/ADRDA) and 12 with cerebrovascular disease (CVD). Mann-Whitney U tests were used to compare performance of controls with other diagnostic groups. The sensitivity and specificity of the tests were determined using Receiver Operating Characteristic curve analyses. The effects of age, gender and years of education on test performance were determined with Spearman's rank correlations. RESULTS: The AD group performed worse than controls on all tests except an attention task. The Hopkins Verbal Learning Test and The Placing Test for episodic memory showed significant discriminative capacity between controls and other groups. Attention and processing speed tests discriminated CVD from controls. Category fluency, episodic memory tests and the CLOX test for executive function distinguished MCI from AD. Spearman's correlations showed negative associations between age and processing speed. Years of education affected performance on all tests, except The Placing Test. CONCLUSIONS: Certain neuropsychological tests have been shown to be sensitive and specific in the differential diagnosis of various types of dementia and may prove to be useful for detection of MCI.

Association of the androgen receptor CAG repeat polymorphism with Alzheimer's disease in men.

We examined the CAG repeat polymorphism in exon 1 of the androgen receptor (AR) in an Oxford cohort of 150 cases (101 men) of definite or probable Alzheimer's disease (AD) and 190 elderly controls (140 men). We found that short alleles (< or = 20 CAG repeats) were associated with AD (adjusted odds ratio = 2.5, 95% confidence intervals: 1.2-5.0) in men, but not in women. This association appeared stronger in early-onset AD (< 65 years). We conclude that this AR polymorphism is of potential relevance to the risk of AD in men.

Matrix metalloprotease-9, placental syncytiotrophoblast and the endothelial dysfunction of pre-eclampsia.

The maternal syndrome of pre-eclampsia is caused by generalized maternal endothelial cell dysfunction, arising directly or indirectly from factors of placental origin. Syncytiotrophoblast membrane microvesicular particles are shed from the placental surface into maternal blood in increased amounts in pre-eclampsia and, in vitro, both inhibit endothelial cell proliferation and cause marked changes in the morphology of the cultured cell monolayers. Because there is evidence that proteolytic activation and degradation of the underlying matrix can cause the same morphological changes, we tested the hypothesis that proteases intrinsic to syncytiotrophoblast microvillous membranes (STBM) are the cause of the in vitro endothelial changes. Purified STBM were analysed by zymography and western blotting. Although we could confirm the presence of urokinase plasminogen activator (uPA) in STBM we could demonstrate no intrinsic activity presumably because of its association with the plasminogen activator inhibitor-2 (PAI-2) which is also a component of STBM. We detected gelatinase activity and showed that it was due to the matrix metalloproteinase-9 (MMP-9). Its presence was confirmed in this location by immunohistocytochemistry. Protease inhibitors caused a small reversal of the effects of STBM on morphology and no effect on inhibition of proliferation. We conclude that the effect of STBM on endothelial cells is unlikely to be caused by intrinsic proteases.

Early detection of isolated memory deficits in the elderly: the need for more sensitive neuropsychological tests.

BACKGROUND: Early detection of cognitive decline in the elderly is important because this may precede progression to Alzheimer's disease. The aim of this study was to see whether sensitive neuropsychological tests could identify pre-clinical cognitive deficits and to characterize the cognitive profile of a subgroup with poor memory. METHODS: A neuropsychological test battery was administered to a community-dwelling sample of 155 elderly volunteers who were screened with CAMCOG at enrolment (mean age 74.7 years). The battery included tests of episodic memory. semantic and working memory, language and processing speed. RESULTS: Episodic memory test z scores below 1 S.D. from the cohort mean identified 25 subjects with non-robust' memory performance. This group was compared to the remaining 'robust memory' group with a General Linear Model controlling for age, IQ, education and gender. Test performance was significantly different in all tests for episodic and semantic memory, but not in tests for working memory, processing speed and language. CANTAB paired associates learning and spatial recognition tests identified the highest percentages of those in the 'non-robust memory group. Processing speed partialled out the age effect on memory performance for the whole cohort, but the 'non-robust memory' group's performance was not associated with age or processing speed. CONCLUSIONS: Sensitive neuropsychological tests can detect performance below the norm in elderly people whose performance on MMSE and CAMCOG tests is well within the normal range. Age-related decline in memory performance in a cohort of the elderly may be largely due to inclusion within the cohort of individuals with undetected pre-clinical Alzheimer's disease or isolated memory impairment.

Fibronectin fragments cause an underestimation of plasma fibronectin levels in severe pre-eclampsia.

Elevated fibronectin (Fn) concentrations in plasma from pregnant women have been suggested to be predictive for the development of pre-eclampsia. However, reported correlations between Fn concentration with gestational age or disease severity appear to be confounded by several variables. Our finding of degradation products of Fn in plasma from patients with severe pre-eclampsia led to a study of whether their presence could influence immunological and functional measurements of intact plasma Fn. Plasma samples (10 control pregnant and 10 severe pre-eclampsia patients) were studied for the presence of intact Fn and fragments by SDS-PAGE and Western blotting. Percentages of immunoreactive Fn fragmentation in control plasma (9.37 +/- 6.7%) and severe pre-eclampsia plasma (62.57 +/- 7.0%) were determined by densitometric scanning. Immunoassays by ELISA were performed on normal plasma samples and on purified Fn in the absence or presence of plasma digests of pure Fn. Artefactual underestimations of Fn concentration occurred in the presence of Fn fragments. The percentage underestimation increased with increasing digestion times (1 h, 46.52 +/- 3.69%; 3 h, 77.5 +/- 7.18%; 4 h, 100%) and with increasing concentrations of Fn digest products (1h) added to normal plasma samples (n = 10) (40 micrograms, 23 +/- 8.1%; 125 micrograms, 36.33 +/- 5.1%; 250 micrograms, 43.66 +/- 6.5%). The underestimation of Fn concentration in the presence of Fn fragments suggests that ELISAs for Fn may be unreliable and thus lose their predictive value in these patients. Opsonic activities of control pregnant and severe pre-eclamptic plasma were determined by gelatin-latex agglutination assay. The ratios of opsonic activity to Fn concentration in plasma from patients with pre-eclampsia were significantly lower than those of control pregnant plasma samples (p < 0.008). The impaired gelatin-latex agglutination of Fn in pre-eclamptic plasma suggests that Fn fragmentation could have biological sequelae in vivo.

Degradation of fibronectin in association with vascular endothelial disruption in preeclampsia.

The objectives of this study were (1) To assess human umbilical cord vein endothelial cell (HUVEC) fibronectin (Fn) content and integrity in patients with preeclampsia and (2) to investigate the ability of Fn and Fn fragments (FnDP) to disrupt endothelial cell attachment to an Fn matrix through modulation of plasminogen activator activity. Intact Fn was released from normal cord veins, while Fn and FnDP (70 and 21 kd) were released from cord veins in culture from patients with severe preeclampsia. Factor VIII and Fn immunostaining of normal cord sections revealed endothelial integrity and low Fn content, while immunostaining of cord sections from patients with preeclampsia revealed a disrupted endothelium and high concentrations of Fn. Both intact Fn and FnDP isolated from patient plasma or prepared by plasmin digestion of pure Fn had no effect on chromium 51 release from HUVECs. These FnDP, but not intact Fn, stimulated HUVEC urokinase plasminogen activator production within 2 hours (p < 0.05) and caused a time- and concentration-dependent detachment and disruption of the HUVEC monolayers and HUVEC-mediated degradation of immobilized iodine 125-labeled Fn underneath the HUVEC monolayer (p < 0.02) after 2 hours. This 125I-labeled Fn release was enhanced by plasminogen and inhibited by aprotinin. Thus FnDP appear to cause endothelial cell disruption that may be due to plasmin generation in vitro.

Serial measurements of circulating tissue plasminogen activator and fibrin(ogen) degradation products predict outcome in gestational proteinuric hypertension.

Gestational proteinuric hypertension (GPH), a major cause of maternal death, may be characterised by hypertension and proteinuria alone or may progress to disturbed coagulation and multiorgan failure. Since the condition can only be reversed by termination of pregnancy, there is a need for reliable indicators of severity. We found circulating levels of tissue plasminogen activator (tPA) (27.98 +/- 2.12 v. 7.17 +/- 0.81 ng/ml, mean +/- SEM), fibrin(ogen) degradation products (FDP) (7.55 +/- 1.99 v. 1.92 +/- 0.47 micrograms/ml) and fibronectin (221 +/- 15.2 v. 120 +/- 15.2 micrograms/ml) to be significantly increased in 21 patients with severe GPH when compared with 21 normotensive, age- and gestational age-matched pregnant controls. More importantly, patients who developed severe GPH showed a progressive increase in tPA and FDP levels with time. This was in contrast to patients who had hypertension and proteinuria alone, in whom tPA and FDP concentrations did not increase. Parallel measurements did not reveal a fall in platelet count or an increase in urinary protein excretion in patients who subsequently progressed to severe disease. Our findings may be of assistance to clinicians faced with the need to prolong pregnancy in patients with GPH in order to ensure fetal viability.

Plasma fibronectin levels during acute rejection and acute tubular necrosis in renal transplant patients.

Fibronectin (Fn), an acute phase glycoprotein synthesized by the liver, has an important immunomodulatory role. We have investigated the changes in plasma Fn in patients after renal transplantation in order to determine whether these changes predict graft injury or rejection episodes. Besides normal healthy controls, healthy pregnant controls, and a trauma control group, we used two groups of chronic renal failure patients as controls: group I, patients with end-stage renal failure (ESRF) on peritoneal dialysis; group II, patients with ESRF on hemodialysis. These were compared with two groups of renal transplant patients: group III, patients 3 months after successful renal transplantation; group IV, patients studied sequentially 10 days immediately posttransplantation. The renal transplant patients were treated with low-dose cyclosporine, azathioprine, and steroids. Citrated plasma samples were collected for Fn assay by a sandwich-type ELISA and for SDS-PAGE analysis and Western blotting. The mean plasma Fn levels were as follows: healthy controls 311.6 SEM, 13.5 micrograms/ml; healthy pregnant controls 357 SEM, 5.9 micrograms/ml; trauma controls 262.3 SEM 31.7, micrograms/ml; group I 169 SEM, 25.1 micrograms/ml; group II 199 SEM, 27.2 micrograms/ml; group III 272 SEM, 21.7 micrograms/ml; group IV 212 SEM, 27.4 micrograms/ml (day 3 postop). There was a significant difference in the plasma Fn levels on day 3 posttransplant between the patients with delayed and immediate renal function (P less than 0.03) (group IV). A significant decrease in plasma Fn levels occurred immediately after steroid therapy was stopped (P less than 0.03) in patients treated for acute rejection. Plasma Fn levels were significantly decreased in the presence of delayed graft function but did not predict rejection.