Structural brain changes and all-cause mortality in the elderly population-the mediating role of inflammation

Increases in regional brain volume across two native South American male populations

Industrialized environments, despite benefits such as higher levels of formal education and lower rates of infections, can also have pernicious impacts upon brain atrophy. Partly for this reason, comparing age-related brain volume trajectories between industrialized and non-industrialized populations can help to suggest lifestyle correlates of brain health. The Tsimane, indigenous to the Bolivian Amazon, derive their subsistence from foraging and horticulture and are physically active. The Moseten, a mixed-ethnicity farming population, are physically active but less than the Tsimane. Within both populations (N = 1024; age range = 46-83), we calculated regional brain volumes from computed tomography and compared their cross-sectional trends with age to those of UK Biobank (UKBB) participants (N = 19,973; same age range). Surprisingly among Tsimane and Moseten (T/M) males, some parietal and occipital structures mediating visuospatial abilities exhibit small but significant increases in regional volume with age. UKBB males exhibit a steeper negative trend of regional volume with age in frontal and temporal structures compared to T/M males. However, T/M females exhibit significantly steeper rates of brain volume decrease with age compared to UKBB females, particularly for some cerebro-cortical structures (e.g., left subparietal cortex). Across the three populations, observed trends exhibit no interhemispheric asymmetry. In conclusion, the age-related rate of regional brain volume change may differ by lifestyle and sex. The lack of brain volume reduction with age is not known to exist in other human population, highlighting the putative role of lifestyle in constraining regional brain atrophy and promoting elements of non-industrialized lifestyle like higher physical activity.

Associations of neuroinflammatory IL-6 and IL-8 with brain atrophy, memory decline, and core AD biomarkers - in cognitively unimpaired older adults

Concentrations of pro-inflammatory cytokines -interleukin-6 (IL-6) and interleukin-8 (IL-8) - are increased with age and in Alzheimer's disease (AD). It is not clear whether concentrations of IL-6 and IL-8 in the central nervous system predict later brain and cognitive changes over time nor whether this relationship is mediated by core AD biomarkers. Here, 219 cognitively healthy older adults (62-91 years), with baseline cerebrospinal fluid (CSF) measures of IL-6 and IL-8 were followed over time - up to 9 years - with assessments that included cognitive function, structural magnetic resonance imaging, and CSF measurements of phosphorylated tau (p-tau) and amyloid-β (Aβ-42) concentrations (for a subsample). Higher baseline CSF IL-8 was associated with better memory performance over time in the context of lower levels of CSF p-tau and p-tau/Aβ-42 ratio. Higher CSF IL-6 was related to less CSF p-tau changes over time. The results are in line with the hypothesis suggesting that an up-regulation of IL-6 and IL-8 in the brain may play a neuroprotective role in cognitively healthy older adults with lower load of AD pathology.

Hypertension and small vessel disease: do the drugs work?

Associations of hypertension with ischaemic stroke and intracerebral haemorrhage, particularly when attributed to cerebral small vessel disease, are well established. While it seems plausible that treating hypertension should prevent small vessel disease from developing or progressing, there is limited evidence demonstrating this. This article critically appraises the evidence answering this clinical question. Hypertension is also closely associated with chronic kidney disease, with anatomical and functional similarities between the vasculature of the brain and kidneys leading to the hypothesis that shared multi-system pathophysiological processes may be involved. Therefore, the article also summarises data on prevention of progression of chronic kidney disease. Evidence supports a target blood pressure of <130/80 mmHg to optimally prevent progression of both small vessel disease and chronic kidney disease. However, future studies are needed to determine long-term effects of more intensive blood pressure treatment targets on small vessel disease progression and incident dementia.

The Indigenous South American Tsimane Exhibit Relatively Modest Decrease in Brain Volume With Age Despite High Systemic Inflammation

Brain atrophy is correlated with risk of cognitive impairment, functional decline, and dementia. Despite a high infectious disease burden, Tsimane forager-horticulturists of Bolivia have the lowest prevalence of coronary atherosclerosis of any studied population and present few cardiovascular disease (CVD) risk factors despite a high burden of infections and therefore inflammation. This study (a) examines the statistical association between brain volume (BV) and age for Tsimane and (b) compares this association to that of 3 industrialized populations in the United States and Europe. This cohort-based panel study enrolled 746 participants aged 40-94 (396 males), from whom computed tomography (CT) head scans were acquired. BV and intracranial volume (ICV) were calculated from automatic head CT segmentations. The linear regression coefficient estimate β^T of the Tsimane (T), describing the relationship between age (predictor) and BV (response, as a percentage of ICV), was calculated for the pooled sample (including both sexes) and for each sex. β^T was compared to the corresponding regression coefficient estimate β^R of samples from the industrialized reference (R) countries. For all comparisons, the null hypothesis β T = β R was rejected both for the combined samples of males and females, as well as separately for each sex. Our results indicate that the Tsimane exhibit a significantly slower decrease in BV with age than populations in the United States and Europe. Such reduced rates of BV decrease, together with a subsistence lifestyle and low CVD risk, may protect brain health despite considerable chronic inflammation related to infectious burden.

Magnetic resonanse imaging as a prognostic tool in encephalitis in children

We provide the data on the modern use of MRI of different modalities as a prognostic tool in the encephalitis diagnostics in pediatrics. According to the recent scientific knowledge, this implementation is possible, but its efficacy depends on the modality of MRI: structural, functional or MRI with contrast. Structural MRI efficacy in children with encephalitis is dubious and clearly depends on the etiology and phase of the inflammatory process. In the recent years, the implementation of the functional MRI methods (DTI MRS) and MRI with contrast significantly changed the imaging practice; there are some reports that these modalities of MRI are more effective as a prognostic tool in encephalitis than the structural one. Thus, a future research in this field is needed.

The trajectory of C-reactive protein serum levels in older hip fracture patients with postoperative delirium

OBJECTIVES

Important precipitating risk factors for delirium such as infections, vascular disorders, and surgery are accompanied by a systemic inflammatory response. Systemic inflammatory mediators can induce delirium in susceptible individuals. Little is known about the trajectory of systemic inflammatory markers and their role in the development and outcome of delirium.

METHODS

This is a prospective cohort study of older patients undergoing acute surgery for hip fracture. Baseline characteristics were assessed preoperatively. During hospital admission, presence of delirium was assessed daily according to the Confusion Assessment Method criteria. This study compared the trajectory of serum levels of the C-reactive protein (CRP) between people with and without postoperative delirium. Blood samples were taken at baseline and at postoperative day 1 through postoperative day 5.

RESULTS

Forty-one out of 121 patients developed postoperative delirium after hip fracture surgery. Longitudinal analysis of the trajectory of serum CRP levels using the Generalized Estimating Equations (GEE) method identified that higher CRP levels were associated with postoperative delirium. CRP levels were higher from postoperative day 2 through postoperative day 5. No significant differences in serum CRP levels were found when we compared patients with short (1-2 days) and more prolonged delirium (3 days or more).

CONCLUSIONS

Delirium is associated with an increased systemic inflammatory response, and our results suggest that CRP plays a role in the underlying (inflammatory-vascular) pathological pathway of postoperative delirium.

Fatty Acids, Antioxidants and Physical Activity in Brain Aging

Polyunsaturated fatty acids and antioxidants are important mediators in the central nervous system. Lipid derivatives may control the production of proinflammatory agents and regulate NF-κB activity, microglial activation, and fatty acid oxidation; on the other hand, antioxidants, such as glutathione and ascorbate, have been shown to signal through transmitter receptors and protect against acute and chronic oxidative stress, modulating the activity of different signaling pathways. Several authors have investigated the role of these nutrients in the brains of the young and the aged in degenerative diseases such as Alzheimer’s and Parkinson’s, and during brain aging due to adiposity- and physical inactivity-mediated metabolic disturbances, chronic inflammation, and oxidative stress. Through a literature review, we aimed to highlight recent data on the role of adiposity, fatty acids, antioxidants, and physical inactivity in the pathophysiology of the brain and in the molecular mechanisms of senescence. Data indicate the complexity and necessity of endogenous/dietary antioxidants for the maintenance of redox status and the control of neuroglial signaling under stress. Recent studies also indicate that omega-3 and -6 fatty acids act in a competitive manner to generate mediators for energy metabolism, influencing feeding behavior, neural plasticity, and memory during aging. Finding pharmacological or dietary resources that mitigate or prevent neurodegenerative affections continues to be a great challenge and requires additional effort from researchers, clinicians, and nutritionists in the field.