Potentials of incretin-based therapies in dementia and stroke in type 2 diabetes mellitus

Patients with type 2 diabetes mellitus are at risk for accelerated cognitive decline and dementia. Furthermore, their risk of stroke is increased and their outcome after stroke is worse than in those without diabetes. Incretin-based therapies are a class of antidiabetic agents that are of interest in relation to these cerebral complications of diabetes. Two classes of incretin-based therapies are currently available: the glucagon-like-peptide-1 agonists and the dipeptidyl peptidase-4 -inhibitors. Independent of their glucose-lowering effects, incretin-based therapies might also have direct or indirect beneficial effects on the brain. In the present review, we discuss the potential of incretin-based therapies in relation to dementia, in particular Alzheimer's disease, and stroke in patients with type 2 diabetes. Experimental studies on Alzheimer's disease have found beneficial effects of incretin-based therapies on cognition, synaptic plasticity and metabolism of amyloid-β and microtubule-associated protein tau. Preclinical studies on incretin-based therapies in stroke have shown an improved functional outcome, a reduction of infarct volume as well as neuroprotective and neurotrophic properties. Both with regard to the treatment of Alzheimer's disease, and with regard to prevention and treatment of stroke, randomized controlled trials in patients with or without diabetes are underway. In conclusion, experimental studies show promising results of incretin-based therapies at improving the outcome of Alzheimer's disease and stroke through glucose-independent pleiotropic effects on the brain. If these findings would indeed be confirmed in large clinical randomized controlled trials, this would have substantial impact

Applicability of diagnostic constructs for cognitive impairment in patients with type 2 diabetes mellitus

Aims: Type 2 diabetes mellitus (T2DM) is associated with subtle cognitive changes, but also with more severe stages of cognitive dysfunction, including mild cognitive impairment (MCI) and dementia. For these severe stages, it is uncertain which domains are primarily affected and if all patients with impairment are captured by formal criteria for MCI or dementia. Methods: Ninety-five patients with T2DM suspected of cognitive impairment, identified through screening in primary care, underwent neuropsychological examination assessing five different domains. MCI or dementia were diagnosed using formal criteria. Results: Forty-seven participants (49%) had impairment on at least one domain, most often involving memory (30%), information processing speed (22%) and visuoperception and construction (22%). Of these 47 people, 29 (62%) had multi-domain impairment. Of the 47 participants with objective impairment, 36 (77%) met criteria for MCI, three (6%) for dementia and eight (17%) met neither diagnosis, mostly because these patients did not complain about acquired dysfunction. Conclusions: This study shows that the clinical diagnostic evaluation of cognitive impairment in patients with T2DM should take into account that multiple domains can be affected and that not all patients with objective cognitive impairment fulfill criteria for MCI or dementia. (C) 2018 Elsevier B.V. All rights reserved

Applicability of diagnostic constructs for cognitive impairment in patients with type 2 diabetes mellitus

Aims: Type 2 diabetes mellitus (T2DM) is associated with subtle cognitive changes, but also with more severe stages of cognitive dysfunction, including mild cognitive impairment (MCI) and dementia. For these severe stages, it is uncertain which domains are primarily affected and if all patients with impairment are captured by formal criteria for MCI or dementia. Methods: Ninety-five patients with T2DM suspected of cognitive impairment, identified through screening in primary care, underwent neuropsychological examination assessing five different domains. MCI or dementia were diagnosed using formal criteria. Results: Forty-seven participants (49%) had impairment on at least one domain, most often involving memory (30%), information processing speed (22%) and visuoperception and construction (22%). Of these 47 people, 29 (62%) had multi-domain impairment. Of the 47 participants with objective impairment, 36 (77%) met criteria for MCI, three (6%) for dementia and eight (17%) met neither diagnosis, mostly because these patients did not complain about acquired dysfunction. Conclusions: This study shows that the clinical diagnostic evaluation of cognitive impairment in patients with T2DM should take into account that multiple domains can be affected and that not all patients with objective cognitive impairment fulfill criteria for MCI or dementia

Sex differences in memory clinic patients with possible vascular cognitive impairment

Introduction: We aimed to establish sex differences in vascular brain damage of memory clinic patients with possible vascular cognitive impairment (VCI). Methods: A total of 860 memory clinic patients (aged 67.7 ± 8.5; 46% female) with cognitive complaints and vascular brain damage (ie, possible VCI) from the prospective TRACE-VCI (Utrecht-Amsterdam Clinical Features and Prognosis in Vascular Cognitive Impairment) cohort study with 2-year follow-up were included. Age-adjusted female-to-male differences were calculated with general linear models, for demographic variables, vascular risk factors, clinical diagnosis, cognitive performance, and brain magnetic resonance imaging markers. Results: We found no difference in age nor distribution of clinical diagnoses between females and males. Females performed worse on the MMSE (Mini-Mental State Examination) and CAMCOG (Cognitive and Self-Contained Part of the Cambridge Examination for Mental Disorders of the Elderly). Females had a larger white matter hyperintensity volume, while males more often showed (lacunar) infarcts. There was no difference in microbleed prevalence. Males had smaller normalized total brain and gray matter volumes. During follow-up, occurrence of cognitive decline and institutionalization was comparable, but mortality was higher in males. Discussion: Our results suggest that susceptibility and underlying etiology of VCI might differ by sex. Males seem to have more large vessel brain damage compared to females that have more small vessel brain damage

Cerebral amyloid burden is associated with white matter hyperintensity location in specific posterior white matter regions

White matter hyperintensities (WMHs) are a common manifestation of cerebral small vessel disease. WMHs are also frequently observed in patients with familial and sporadic Alzheimer's disease, often with a particular posterior predominance. Whether amyloid and tau pathologies are linked to WMH occurrence is still debated. We examined whether cerebral amyloid and tau burden, reflected in cerebrospinal fluid amyloid-beta 1-42 (Aβ-42) and phosphorylated tau (p-tau), are related to WMH location in a cohort of 517 memory clinic patients. Two lesion mapping techniques were performed: voxel-based analyses and region of interest-based linear regression. Voxelwise associations were found between lower Aβ-42 and parieto-occipital periventricular WMHs. Regression analyses demonstrated that lower Aβ-42 correlated with larger WMH volumes in the splenium of the corpus callosum and posterior thalamic radiation, also after controlling for markers of vascular disease. P-tau was not consistently related to WMH occurrence. Our findings indicate that cerebral amyloid burden is associated with WMHs located in specific posterior white matter regions, possibly reflecting region-specific effects of amyloid pathology on the white matter

Cerebral amyloid burden is associated with white matter hyperintensity location in specific posterior white matter regions

White matter hyperintensities (WMHs) are a common manifestation of cerebral small vessel disease. WMHs are also frequently observed in patients with familial and sporadic Alzheimer's disease, often with a particular posterior predominance. Whether amyloid and tau pathologies are linked to WMH occurrence is still debated. We examined whether cerebral amyloid and tau burden, reflected in cerebrospinal fluid amyloid-beta 1-42 (Aβ-42) and phosphorylated tau (p-tau), are related to WMH location in a cohort of 517 memory clinic patients. Two lesion mapping techniques were performed: voxel-based analyses and region of interest-based linear regression. Voxelwise associations were found between lower Aβ-42 and parieto-occipital periventricular WMHs. Regression analyses demonstrated that lower Aβ-42 correlated with larger WMH volumes in the splenium of the corpus callosum and posterior thalamic radiation, also after controlling for markers of vascular disease. P-tau was not consistently related to WMH occurrence. Our findings indicate that cerebral amyloid burden is associated with WMHs located in specific posterior white matter regions, possibly reflecting region-specific effects of amyloid pathology on the white matter

The Clinical Phenotype of Vascular Cognitive Impairment in Patients with Type 2 Diabetes Mellitus

BACKGROUND: Type 2 diabetes mellitus (T2DM) increases the risk of vascular cognitive impairment (VCI). It is unknown which type of vascular lesions and co-morbid etiologies, in particular Alzheimer's disease pathology, are associated with T2DM in patients with VCI, and how this relates to cognition and prognosis. OBJECTIVE: To compare brain MRI and cerebrospinal fluid (CSF) markers, cognition, and prognosis in patients with possible VCI with and without T2DM. METHODS: We included 851 memory clinic patients with vascular brain injury on MRI (i.e., possible VCI) from a prospective cohort study (T2DM: n = 147, 68.4±7.9 years, 63% men; no T2DM: n = 704, 67.6±8.5 years, 52% men). At baseline, we assessed between-group differences in brain MRI abnormalities, CSF markers of Alzheimer's disease, and cognitive profile. After two years follow-up, we compared occurrence of cognitive decline, stroke, and death. RESULTS: The distribution of clinical diagnoses did not differ between patients with and without T2DM. T2DM patients had more pronounced brain atrophy (total and white matter volume), and more lacunar infarcts, whereas microbleeds were less common (all p < 0.05). CSF amyloid-β levels were similar between the groups. T2DM patients performed worse on working memory (effect size: - 0.17, p = 0.03) than those without, whereas performance on other domains was similar. During follow-up, risk of further cognitive decline was not increased in T2DM.∥Conclusion: In patients with possible VCI, presence of T2DM is related to more pronounced brain atrophy and a higher burden of lacunar infarcts, but T2DM does not have a major impact on cognitive profile or prognosis.∥

The Clinical Phenotype of Vascular Cognitive Impairment in Patients with Type 2 Diabetes Mellitus

Background: Type 2 diabetes mellitus (T2DM) increases the risk of vascular cognitive impairment (VCI). It is unknown which type of vascular lesions and co-morbid etiologies, in particular Alzheimer's disease pathology, are associated with T2DM in patients with VCI, and how this relates to cognition and prognosis. Objective: To compare brain MRI and cerebrospinal fluid (CSF) markers, cognition, and prognosis in patients with possible VCI with and without T2DM. Methods: We included 851 memory clinic patients with vascular brain injury on MRI (i.e., possible VCI) from a prospective cohort study (T2DM: n = 147, 68.4 +/- 7.9 years, 63% men; no T2DM: n = 704, 67.6 +/- 8.5 years, 52% men). At baseline, we assessed between-group differences in brain MRI abnormalities, CSF markers of Alzheimer's disease, and cognitive profile. After two years follow-up, we compared occurrence of cognitive decline, stroke, and death. Results: The distribution of clinical diagnoses did not differ between patients with and without T2DM. T2DM patients had more pronounced brain atrophy (total and white matter volume), and more lacunar infarcts, whereas microbleeds were less common (all p < 0.05). CSF amyloid-beta levels were similar between the groups. T2DM patients performed worse on working memory (effect size: -0.17, p = 0.03) than those without, whereas performance on other domains was similar. During follow-up, risk of further cognitive decline was not increased in T2DM. Conclusion: In patients with possible VCI, presence of T2DM is related to more pronounced brain atrophy and a higher burden of lacunar infarcts, but T2DM does not have a major impact on cognitive profile or prognosis