Normal-appearing white matter permeability distinguishes poor cognitive performance in processing speed and working memory

Tissue damage within normal appearing white matter in early multiple sclerosis: assessment by the ratio of T1- and T2-weighted MR image intensity

Histopathological and magnetic resonance imaging (MRI) studies have shown white matter (WM) damage in early stages of multiple sclerosis (MS) beyond the apparent T2-hyperintense lesions. These changes in normal appearing WM (NAWM) are important with regard to the clinical picture and prognosis. However, the detection of changes within NAWM has so far required special imaging techniques commonly not available in clinical routine and, hence, at large scale. The purpose of this study was to detect MS-related damage of NAWM by conventional MRI. As, within NAWM, the myelin content mainly drives the T1-weighted (T1w) signal, we scaled it by the T2w signal. We tested the hypothesis that the mean T1w/T2w ratio of NAWM is decreased in MS compared to healthy controls (HC) and that it correlates with clinical measures. We developed a pipeline to determine the individual mean values of this ratio within NAWM. We studied 244 patients in early disease stages of MS (mean age 37 ± 10 years, mean disease duration 3.1 ± 2.3, Expanded Disability Status Scale 1.3 ± 1), and 78 HC (mean age 31 ± 8 years). Compared to HC, the mean T1w/T2w ratio was lowered in the patient group (P < 0.001). The difference remained significant after restricting the analysis to patients with a disease duration of 5 years or less and without disease modifying drugs. Our measures also correlated with clinical scores. We believe that the mean T1w/T2w ratio is a promising candidate to assess MS-related tissue damage within NAWM at large scale.

Ethnicity/culture modulates the relationships of the haptoglobin (Hp) 1-1 phenotype with cognitive function in older individuals with type 2 diabetes

OBJECTIVE

The haptoglobin (Hp) genotype has been associated with cognitive function in type 2 diabetes. Because ethnicity/culture has been associated with both cognitive function and Hp genotype frequencies, we examined whether it modulates the association of Hp with cognitive function.

METHODS

This cross-sectional study evaluated 787 cognitively normal older individuals (>65 years of age) with type 2 diabetes participating in the Israel Diabetes and Cognitive Decline study. Interactions in two-way analyses of covariance compared Group (Non-Ashkenazi versus Ashkenazi Jews) on the associations of Hp phenotype (Hp 1-1 versus non- Hp 1-1) with five cognitive outcome measures. The primary control variables were age, gender, and education.

RESULTS

Compared with Ashkenazi Jews, non-Ashkenazi Jews with the Hp 1-1 phenotype had significantly poorer cognitive function than non-Hp 1-1 in the domains of Attention/Working Memory (p = 0.035) and Executive Function (p = 0.023), but not in Language/Semantic Categorization (p = 0.432), Episodic Memory (p = 0.268), or Overall Cognition (p = 0.082). After controlling for additional covariates (type 2 diabetes-related characteristics, cardiovascular risk factors, Mini-mental State Examination, and extent of depressive symptoms), Attention/Working Memory (p = 0.038) and Executive Function (p = 0.013) remained significant.

CONCLUSIONS

Older individuals from specific ethnic/cultural backgrounds with the Hp 1-1 phenotype may benefit more from treatment targeted at decreasing or halting the detrimental effects of Hp 1-1 on the brain. Future studies should examine differential associations of Hp 1-1 and cognitive impairment, especially for groups with high prevalence of both, such as African-Americans and Hispanics.

Secondary Progression in Multiple Sclerosis: Neuronal Exhaustion or Distinct Pathology?

Prevention of progression in neurological diseases, particularly in multiple sclerosis (MS) but also in neurodegenerative diseases, remains a significant challenge. MS patients switch from a relapsing-remitting to a progressive disease course, but it is not understood why and how this conversion occurs and why some patients never experience disease progression. Do aging and accumulation of neuronal damage induce progression, or do cognitive symptoms and accelerated grey matter (GM) atrophy point to distinct processes affecting networks? This review weighs accepted dogma against real data on the secondary progressive phase of the disease, highlighting current challenges in this important field and directions towards development of treatment strategies to slow or prevent progression of disability.

Haptoglobin genotype modulates the relationships of glycaemic control with cognitive function in elderly individuals with type 2 diabetes

AIMS/HYPOTHESIS

The purpose of this study was to investigate whether the association of glycaemic control with cognitive function is modulated by the haptoglobin 1-1 (Hp 1-1) genotype in cognitively normal elderly individuals with type 2 diabetes.

METHODS

In this cross-sectional study, we examined 793 participants who were genotyped for Hp (80 Hp 1-1 carriers and 713 Hp 1-1 non-carriers) enrolled in the Israel Diabetes and Cognitive Decline (IDCD) study. Glycaemic control was operationally defined by HbA1c level. The outcome measures were performance in four cognitive domains (episodic memory, attention/working memory, language/semantic categorisation, executive function) and overall cognition, a composite of the domains. Effect sizes were obtained from hierarchical linear regression analyses for each outcome measure, controlling for demographics, type 2 diabetes-related characteristics, cardiovascular risk factors, and their interactions with Hp genotype.

RESULTS

Interaction analyses showed significantly stronger associations of HbA1c with poorer cognitive function among Hp 1-1 carriers than non-carriers; attention/working memory (p < 0.001) and overall cognition (p = 0.003). For these two cognitive domains, associations were significant for Hp 1-1 carriers despite the small sample size (p < 0.00001 and p = 0.001, respectively), but not for non-carriers.

CONCLUSIONS/INTERPRETATION

Our findings suggest that patients with type 2 diabetes and poor glycaemic control carrying the Hp 1-1 genotype may be at increased risk of cognitive impairment, particularly in the attention/working memory domain. The association of glycaemic control with this domain may indicate cerebrovascular mechanisms.