Incretin hormones, insulin, glucagon and advanced glycation end products in relation to cognitive function in older people with and without diabetes, a population-based study.

AIM: The aim of this observational study was to investigate relationships between physiological levels of glucometabolic biomarkers and cognitive test results in a population-based setting. METHODS: Cross-sectional data were obtained from the Swedish population-based Malmö Diet and Cancer Study Re-examination 2007-2012 comprising 3001 older people (mean age 72 years). Through oral glucose tolerance testing (OGTT), fasting and post-load levels of serum insulin, plasma glucagon, serum glucose-dependent insulinotropic peptide (GIP) and plasma glucagon-like peptide-1 (GLP-1) were measured. Insulin resistance and insulin sensitivity levels were calculated. In 454 participants, advanced glycation end products (AGEs) were estimated through skin autofluorescence. Associations between biomarkers and two cognitive tests, the Mini-Mental State Examination (MMSE) and A Quick Test of Cognitive Speed (AQT) respectively, were explored in multiple regression analyses. RESULTS: Positive associations following adjustments for known prognostic factors were found between MMSE scores and insulin sensitivity (B = 0.822, P = 0.004), 2-h plasma glucagon (B = 0.596, P = 0.026), 2-h serum GIP (B = 0.581, P = 0.040) and 2-h plasma GLP-1 (B = 0.585, P = 0.038), whereas negative associations were found between MMSE scores and insulin resistance (B = -0.734, P = 0.006), fasting plasma GLP-1 (B = -0.544, P = 0.033) and AGEs (B = -1.459, P = 0.030) were found. CONCLUSIONS: Higher levels of insulin sensitivity, GIP and GLP-1 were associated with better cognitive outcomes, but AGEs were associated with worse outcomes, supporting evidence from preclinical studies. Glucagon was linked to better outcomes, which could possibly reflect neuroprotective properties similar to the related biomarker GLP-1 which has similar intracellular properties. Longitudinal and interventional studies are needed to further evaluate neuromodulating effects of these biomarkers. Abstract presented at the European Association for the Study of Diabetes (EASD) 2019, Barcelona, Spain.

Biomarkers of microvascular endothelial dysfunction predict incident dementia: a population-based prospective study.

BACKGROUND: Cerebral endothelial dysfunction occurs in a spectrum of neurodegenerative diseases. Whether biomarkers of microvascular endothelial dysfunction can predict dementia is largely unknown. We explored the longitudinal association of midregional pro-atrial natriuretic peptide (MR-proANP), C-terminal endothelin-1 (CT-proET-1) and midregional proadrenomedullin (MR-proADM) with dementia and subtypes amongst community-dwelling older adults. METHODS: A population-based cohort of 5347 individuals (men, 70%; age, 69 ± 6 years) without prevalent dementia provided plasma for determination of MR-proANP, CT-proET-1 and MR-proADM. Three-hundred-and-seventy-three patients (7%) were diagnosed with dementia (120 Alzheimer's disease, 83 vascular, 102 mixed, and 68 other aetiology) over a period of 4.6 ± 1.3 years. Relations between baseline biomarker plasma concentrations and incident dementia were assessed using multivariable Cox regression analysis. RESULTS: Higher levels of MR-proANP were significantly associated with increased risk of all-cause and vascular dementia (hazard ratio [HR] per 1 SD: 1.20, 95% confidence interval [CI], 1.07-1.36; P = 0.002, and 1.52; 1.21-1.89; P < 0.001, respectively). Risk of all-cause dementia increased across the quartiles of MR-proANP (p for linear trend = 0.004; Q4, 145-1681 pmol L-1 vs. Q1, 22-77 pmol L-1 : HR: 1.83; 95%CI: 1.23-2.71) and was most pronounced for vascular type (p for linear trend = 0.005: HR: 2.71; 95%CI: 1.14-6.46). Moreover, the two highest quartiles of CT-proET-1 predicted vascular dementia with a cut-off value at 68 pmol L-1 (Q3-Q4, 68-432 pmol L-1 vs. Q1-Q2,4-68 pmol L-1 ; HR: 1.94; 95%CI: 1.12-3.36). Elevated levels of MR-proADM indicated no increased risk of developing dementia after adjustment for traditional risk factors. CONCLUSIONS: Elevated plasma concentration of MR-proANP is an independent predictor of all-cause and vascular dementia. Pronounced increase in CT-proET-1 indicates higher risk of vascular dementia.

Hearing difficulties, uptake, and outcomes of hearing aids in people 85 years of age.

OBJECTIVE: The aim of this study was to investigate self-reported hearing difficulties, uptake, and hearing-aid outcomes and their relationships to demographic, cognitive, psychosocial, and health variables in 85 year olds. DESIGN AND STUDY SAMPLE: Three hundred and forty-six elderly adults participated in a survey that included questionnaires and home visits. Fifty-five percent of participants admitted to having hearing difficulties, and 59% of these owned hearing aids. The participants' most frequently cited reason for not acquiring hearing aids was that they did not think their hearing problem was perceived as severe enough. Participants with hearing difficulties who did not own hearing aids showed worse general and mental health. Many of the elderly participants were successful in their rehabilitation, and their hearing-aid outcomes were similar to those of a younger group, with the exception of a greater proportion of non-users among the elderly. CONCLUSION: Many older people with self-reported hearing difficulties do not acquire hearing aids, despite this study's findings that older people are likely to have success with hearing rehabilitation. It is important to make greater efforts to try to increase elderly adults' awareness of hearing loss and the benefits of hearing rehabilitation.

Lack of accuracy for the proposed 'Dubois criteria' in Alzheimer's disease: a validation study from the Swedish brain power initiative.

BACKGROUND/AIMS: Our purpose was to investigate whether the new research criteria for Alzheimer's disease proposed in 2007 by Dubois et al. are valid in a naturalistic memory clinic sample. METHOD: Retrospective diagnostic analyses were carried out to compare the traditional diagnostic criteria for dementia with the new criteria suggested by Dubois et al. No patient had gone through all procedures postulated as additional features in the proposed new Dubois criteria. MATERIAL: Two independent experienced geriatricians re-examined 150 complete patients' records. The study physicians were blinded to any of the results of the core and additional features suggested by Dubois et al. to avoid circular diagnostic bias. RESULTS: Among our 96 patients with a clinical diagnosis of subjective cognitive impairment and/or mild cognitive impairment, 2 of the patients with subjective cognitive impairment and 5 patients with mild cognitive impairment would classify as pre-dementia Alzheimer's disease according to the Dubois criteria. In our 23 Alzheimer patients diagnosed clinically, only 12 of the cases fulfilled the criteria for Alzheimer's disease suggested by Dubois et al. INTERPRETATION: The proposed new criteria for Alzheimer's disease are valid in 55% of our patients clinically diagnosed as having full-blown Alzheimer dementia. Additionally, 7.3% 'true' Alzheimer cases will be identified in a group of 96 clinically non-demented patients. Our results show that there is a large heterogeneity in a clinical naturalistic sample of patients with an Alzheimer phenotype. CONCLUSION: There is a need to further validate the currently existing biomarkers in large unselected samples and avoid the pitfall of workup bias and circular diagnostic processes. Additionally, valid age-specific cut-off values for the diagnostic markers in question have to be defined.

High circulating levels of midregional proenkephalin A predict vascular dementia: a population-based prospective study.

Midregional Pro-enkephalin A (MR-PENK A) and N-terminal Protachykinin A (NT-PTA) have been associated with vascular dementia. However, the longitudinal relationship between these biomarkers and incident dementia has not been fully investigated. In the population-based Malmö Preventive Project, circulating levels of MR-PENK A and NT-PTA were determined in a random sample of 5,323 study participants (mean age: 69 ± 6 years) who were followed-up over a period of 4.6 ± 1.6 years. The study sample included 369 patients (7%) who were diagnosed in the same period with dementia. We analyzed relationship of MR-PENK A and NT-PTA with the risk of developing dementia by using multivariable-adjusted Cox regression models adjusted for traditional risk factors. Increased plasma levels of MR-PENK A were associated with higher risk of incident vascular dementia whereas no associations were found with all-cause or Alzheimer dementia. The risk of vascular dementia was mainly conferred by the highest quartile of MR-PENK as compared with lower quartiles. Elevated levels of NT-PTA yielded significant association with all-cause dementia or dementia subtypes. Elevated plasma concentration of MR-PENK A independently predicts vascular dementia in the general population. MR-PENK A may be used as an additional tool for identifying vascular subtype in ambiguous dementia cases.

Beta-blocker therapy and risk of vascular dementia: A population-based prospective study.

There are a few studies that report cognitive impairment as a complication of treatment with beta- blockers. We aimed to evaluate the longitudinal association between use of beta-blockers, as a class, and incident risk of all-cause dementia, vascular dementia, Alzheimer's and mixed dementia in the prospective population-based Malmö Preventive Project. We included 18,063 individuals (mean age 68.2, males 63.4%) followed up for 84,506 person-years. Dementia cases were retrieved from the Swedish National Patient Register and validated by review of medical records and neuroimaging data. We performed propensity score matching analysis, resulting in 3720 matched pairs of beta-blocker users and non-users at baseline, and multivariable Cox proportional-hazards regression. Overall, 122 study participants (1.6%) were diagnosed with dementia during the follow-up. Beta-blocker therapy was independently associated with increased risk of developing vascular dementia, regardless of confounding factors (HR: 1.72, 95%CI 1.01-3.78; p = .048). Conversely, treatment with beta-blockers was not associated with increased risk of all-cause, Alzheimer's and mixed dementia (HR:1.15; 95%CI 0.80-1.66; p = .44; HR:0.85; 95%CI 0.48-1.54; P = .59 and HR:1.35; 95%CI 0.56-3.27; p = .50, respectively). We observed that use of beta-blockers, as a class, is associated with increased longitudinal risk of vascular dementia in the general elderly population, regardless of cardiovascular risk factors, prevalent or incident history of atrial fibrillation, stroke, coronary events and heart failure. Further studies are needed to confirm our findings in the general population and to explore the mechanisms underlying the relationship between use of beta- blockers and increased risk of vascular dementia.

Associations of central and brachial blood pressure with cognitive function: a population-based study.

Previous observational studies on the association between brachial blood pressure (BP) and cognition have reported conflicting results. Central BP has been hypothesized to be more strongly related to cognition than brachial BP. The aim of this study was to assess the association between brachial as well as central BP and cognitive function, both cross-sectionally and with brachial BP measured 17 years before cognitive testing. The study population comprised 2548 individuals aged 61-85 years at follow-up (61.4% women). The cognitive tests administered were A Quick Test of cognitive speed and the Mini Mental State Examination. In fully adjusted linear regressions, small but significant cross-sectional associations were found between higher BP (systolic, diastolic and pulse pressure) and worse results on both of the cognitive tests (P-values <0.05). No significant prospective associations were found. Central BP did not show a stronger association than brachial BP did. After stratification, significant results were mainly found in the group taking BP-lowering drugs at follow-up. In summary, these findings add to existing evidence on the relationship between BP and cognition, but they do not support a superior role of central compared with brachial BP in the elderly.

Lack of replication of association findings in complex disease: an analysis of 15 polymorphisms in prior candidate genes for sporadic Alzheimer's disease.

There is considerable enthusiasm for the prospect of using common polymorphisms (primarily single nucleotide polymorphisms; SNPs) in candidate genes to unravel the genetics of complex disease. This approach has generated a number of findings of loci which are significantly associated with sporadic Alzheimer's disease (AD). In the present study, a total of 15 genes of interest were chosen from among the previously published reports of significant association in AD. Genotyping was performed on polymorphisms within those genes (14 SNPs and one deletion) using Dynamic Allele Specific Hybridization (DASH) in 204 Swedish patients with sporadic late-onset AD and 186 Swedish control subjects. The genes chosen for analysis were; low-density lipoprotein receptor-related protein (LRP1), angiotensin converting enzyme (DCP1), alpha-2-macroglobulin (A2M), bleomycin hydrolase (BLMH), dihydrolipoyl S-succinyltransferase (DLST), tumour necrosis factor receptor superfamily member 6 (TNFRSF6), nitric oxide synthase (NOS3), presenilin 1 (PSEN1), presenilin 2 (PSEN2), butyrylcholinesterase (BCHE), Fe65 (APBB1), oestrogen receptor alpha (ESR1), cathepsin D (CTSD), methylenetetrahydrofolate reductase (MTHFR), and interleukin 1A (IL1A). We found no strong evidence of association for any of these loci with AD in this population. While the possibility exists that the genes analysed are involved in AD (ie they have weak effects and/or are population specific), results reinforce the need for extensive replication studies if we are to be successful in defining true risk factors in complex diseases.

Radial and longitudinal strain and strain rate assessed by speckle-tracking echocardiography in dogs with myxomatous mitral valve disease.

BACKGROUND: Assessment of left ventricular (LV) function using conventional echocardiographic methods is difficult in mitral regurgitation (MR) owing to altered hemodynamic loading conditions. Newer methods such as speckle-tracking echocardiography (STE) provide assessment of LV strain (St) and strain rates (SR). HYPOTHESES: Global St and SR are 1) decreased in dogs with clinical signs of congestive heart failure (CHF) due to myxomatous mitral valve disease (MMVD) compared with clinically healthy dogs, and are 2) associated with conventional echocardiographic indices of MMVD severity. ANIMALS: The study subjects were 93 privately owned dogs with different MMVD severities. METHODS: Prospectively recruited dogs were grouped according to MMVD severity based on echocardiographic evaluation of MR and presence of clinical signs. Global radial and longitudinal St, SR, and indices of LV dyssynchrony were assessed. RESULTS: On group-wise comparisons, dogs with CHF had increased global longitudinal St, global longitudinal and radial SR in systole (SRs), and early diastole (SRe) compared with dogs with no or minimal MR (all P < .04). On multiple regression analyses, these global STE variables increased with degree of MR, but associations with left atrial-to-aortic root ratio (LA/Ao) were best described by second-order polynomial equations. Thus, curvilinear relationships were found for LA/Ao and longitudinal St, SRs, and SRe (all P < .002) and radial St and SRe (all P < .001). CONCLUSIONS AND CLINICAL IMPORTANCE: Assessed by STE, LV function appeared to be augmented in moderate-to-severe disease. However, at CHF stages with greatly enlarged atria, a decrease to levels comparable to dogs with no or minimal MR was observed.

Association of insulin-like growth factor-1 receptor polymorphism in dementia.

There is an increasing interest in how oxidative stress can cause cells to go into apoptosis in both normal ageing and in neurodegenerative disorders. Previous research has implicated insulin-like growth factor-1 (IGF-1) as being involved in the pathogenesis in Alzheimer's disease (AD) by protecting the neurons through reducing neuronal susceptibility to oxidative stress. IGF-1 receptor (IGF-1R) polymorphisms alter cerebral and systemic levels of IGF-1 and may alter the function of the receptor. We genotyped the IGF-1R gene by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) to assess whether this gene polymorphism can be linked to dementia. We used leukocyte DNA from 72 patients with AD, 75 patients with vascular dementia (VaD), 14 patients with mixed dementia (AD+VaD), and a control group consisting of 209 individuals without a history of progressive neurological disorders. Analysis of gene frequency for gender revealed a significant difference between female VaD patients and female controls carrying at least one A allele (OR = 1.8, CI 95% 1.1-2.9, p = 0.02), but not for male patients. In addition, we found a strong tendency to a difference between all cases of female dementia patients and controls carrying the A allele (OR = 1.5, CI 95% 0.99-2.2, p = 0.054). Our results suggest that the A allele of IGF-1R may be involved in the pathogenesis of VaD in females.

GABA transporters (GAT-1) in Alzheimer's disease.

The presynaptically located gamma-aminobutyric acid (GABA) transporter (GAT-1) was studied in a group of patients with Alzheimer's disease (AD) and in a control group using the GAT-1 selective radioligand [3H]tiagabine. Post mortem brain tissue from frontal cortex, temporal cortex, and caudate nucleus from 18 AD patients and 23 age-matched controls were studied. The binding was saturable (Kd 26 nM) and region specific. There were no significant differences between the groups with respect to the binding capacity (Bmax) and binding affinity (Kd). The unaltered [3H]tiagabine binding to GAT-1 protein indicates that intrinsic GABA neurons are spared in Alzheimer's disease.

Cobalamin, folate, methylmalonic acid, homocysteine, and gastritis markers in dementia.

The prevalence of dementia disorders, cobalamin and/or folate deficiency as well as gastritis increases with age. To investigate whether there is an association between these conditions, plasma homocysteine (Hcy), serum methylmalonic acid, serum cobalamin and blood folate concentrations were measured. Gastritis was indirectly diagnosed by measuring serum antibodies against H,K-ATPase, HELICOBACTER PYLORI and intrinsic factor, using enzyme-linked immunosorbent assays. The studied groups consisted of 47 patients with Alzheimer's disease (AD), 9 with AD pathology in combination with additive vascular lesions, 59 with vascular dementia, 8 who were cognitively impaired, and 101 control cases. Plasma Hcy concentrations were significantly elevated in the dementia groups, with the highest levels in patients with vascular pathology. We conclude that hyperhomocysteinemia is a common finding in patients with dementia disorders of different etiologies. The markers for gastritis did not contribute to an elucidation of a possible connection between this condition, dementia disorders, or cobalamin/folate deficiency.

Tau and Abeta42 in cerebrospinal fluid from healthy adults 21-93 years of age: establishment of reference values.

BACKGROUND: Tau protein and the 42-amino acid form of beta-amyloid (Abeta42) measured in cerebrospinal fluid (CSF) have been proposed as potential biochemical diagnostic markers for Alzheimer disease. For the introduction of these assays in clinical practice, adequate reference values are of importance. METHODS: CSF samples were obtained from 231 neurologically and psychiatrically healthy individuals, 21-93 years of age, all with a MiniMental State examination score of 28 or above. Standardized ELISAs were used to measure tau and Abeta42 in CSF. Following IFCC recommendations, we used a rank-based method; the 0.90 and 0.10 fractiles were estimated to establish reference values for CSF-tau and CSF-Abeta42, respectively. Putative confounding factors, such as the influence of the passage of proteins from peripheral blood to CSF, influence of dysfunction of the blood-brain barrier, and freezing and thawing of CSF, were investigated. RESULTS: A correlation with age was found for CSF-tau (r = 0.60; P <0.001). Therefore, separate reference values for different age groups were established for CSF-tau: <300 ng/L in the group 21-50 years of age, <450 ng/L in the group 51-70 years of age, and <500 ng/L in the group 71-93 years of age. CSF-Abeta42 did not correlate with age (r = -0.045), and the reference value was set to >500 ng/L. No correlation was found between blood-brain barrier function and CSF-tau or CSF-Abeta42. CONCLUSIONS: These reference values can be applied when using CSF-tau and CSF-Abeta42 in clinical practice.

No association between the alpha2-macroglobulin (A2M) deletion and Alzheimer's disease, and no change in A2M mRNA, protein, or protein expression.

A polymorphism consisting of a deletion near the 5' splice site of exon 18 on the alpha2-macroglobulin (A2M) gene (A2M-2) has been suggested to be associated with Alzheimer's disease (AD) in family-based studies. We studied the A2M-2 allele together with the ApoE alleles in a large series on patients with AD (n = 449) and age-matched controls (n = 349). Neuropathologically confirmed diagnoses were available in 199 cases (94 AD and 107 control cases). We found no increase in A2M-2 genotype or allele frequencies in AD (27.5% and 14.6%) versus controls (26.4% and 14.9%). In contrast, a marked increase (p < 0.0001) in ApoE epsilon4 genotype or allele frequencies was found in AD (66.6% and 41.2%) as compared with controls (29.8% and 16.5%), suggesting sufficient statistical power in our sample. No relation was found between the A2M-2 and the ApoE epsilon4 allele. No change in A2M exon 17-18 mRNA size or sequence or A2M protein size was found in cases carrying the A2M-2 deletion, suggesting that there is no biological consequences of the A2M intronic deletion. No change in A2M protein level in cerebrospinal fluid was found in AD, suggesting that the A2M-2 allele does not effect the A2M protein expression in the brain. The lack of an association between the A2M-2 allele and AD in the present study, and the lack of abnormalities in the A2M mRNA or protein suggest that the A2M-2 allele is not associated with AD.