Loss of Dickkopf-1 Restores Neurogenesis in Old Age and Counteracts Cognitive Decline

1. Download : Download high-res image (303KB)
2. Download : Download full-size image

Highlights? Dkk1 antagonizes Wnt activity in NPCs ? Loss of Dkk1 increases NPCs, neuronal progeny, and neuronal activity in DG ? Loss of Dkk1 has beneficial effects on affective behavior in the tail suspension test ? Loss of Dkk1 in NPCs restores DG neurogenesis and cognition in old age     

Color-Flow Doppler Sonography in Patients with Subclinical Thyroid Dysfunction

ObjectiveTo assess the value of color-flow Doppler sonography (CFDS) in evaluating intrathyroidal blood flow and velocity in patients with subclinical thyroid dysfunction.MethodsIn this prospective study, patients with subclinical hypothyroidism, patients with subclinical hyperthyroidism, and euthyroid patients without known thyroid autoimmune disease who served as controls were included. Subclinical thyroid dysfunction was defined as normal serum free thyroxine (FT₄) and free triiodothyronine (FT₃) in the presence of high (subclinical hypothyroidism), or lowsuppressed (subclinical hyperthyroidism) serum thyrotropin (TSH) levels. Serum FT₄, FT₃, TSH, and antibodies to thyroid peroxidase and thyroglobulin were measured in all participants. In addition, TSH receptor antibody levels were determined in patients with subclinical hyperthyroidism. All participants underwent conventional sonography and CFDS. Mean peak systolic velocity (PSV) and resistive index were obtained from multiple extranodular thyroid parenchyma samplings and inferior thyroid artery measurements.ResultsThe study population included 27 patients with subclinical hypothyroidism, 15 patients with subclinical hyperthyroidism, and 20 euthyroid patients. Patients with subclinical hypothyroidism had significantly higher mean intrathyroidal PSV values than control patients (19.9 ± 5.6 cm/s vs 15.7 ± 4.4 cm/s; P = .008), whereas patients with subclinical hyperthyroidism had significantly higher mean PSV values than control patients at the inferior thyroid artery level (29.7 ± 10.7 cm/s vs 21.9 ± 6.8 cm/s; P = .014). Compared with control patients, a greater proportion of patients with subclinical hypothyroidism and patients with subclinical hyperthyroidism had marked CFDS patterns (78% vs 15% [P <.001] and 53% vs 15%; [P <.001], respectively). A significant association was found between positivity for thyroid autoantibodies and intense CFDS patterns. No correlation was found between TSH or thyroid hormone levels and CFDS pattern or blood flow velocity.ConclusionWe have demonstrated that significantly increased thyroid blood flow velocity and vascularity are already present in patients with mild thyroid dysfunction.(Endocr Pract. 2010;16:376-381)     

Waist Circumference and Subclinical Thyroid Dysfunction in a Large Cohort of Chinese Men and Women

Objective: The association between subclinical thyroid dysfunction and waist circumference (WC) is still controversial, especially from the perspective of sex differences. We aimed to explore the impact of sex on this relationship in a large Chinese cohort.Methods: This cross-sectional study recruited 13,505 healthy participants (8,346 males, 5,159 females) who were enrolled in a health check program. Clinical data were collected. The association between subclinical thyroid dysfunction and WC of both sexes was analyzed separately after dividing WC into quartiles. Odds ratios (ORs) were calculated by binary logistic regression models, and linear regression analysis was also performed.Results: The prevalence rates of subclinical hyper-and hypothyroidism were significantly lower in males. Binary logistic regression models showed that WC in females with subclinical hypothyroidism had a detrimental effect with an OR of 1.011, but the effect disappeared when we included other covariates. The other ORs indicated no significant effects. The weak negative relationship between WC and thyrotropin was also indicated by linear regression analyses with very low R² values.Conclusion: The current research did not show WC as a risk factor for subclinical thyroid dysfunction in either sex. Regional and ancestral origin differences may account for the variations with other studies.Abbreviations: ALT = alanine aminotransferase; BMI = body mass index; FT3 = free triiodothyronine; FT4 = free thyroxine; TG = triglycerides; TSH = thyroid-stimulating hormone; UA = uric acid; WC = waist circumference     

The Association Between Body Mass Index and Subclinical Thyroid Dysfunction in Different Sexes of Chinese

Objective: To study subclinical thyroid dysfunction (SCTD)—subclinical hyperthyroidism and subclinical hypothyroidism—in Chinese patients in relation to body mass index (BMI) and to determine whether a difference between sexes exists.Methods: This cross-sectional study recruited 13,503 healthy participants (8,345 male, 5,158 female) who participated in a health examination. Clinical data, including anthropometric measurements and serum parameters, were collected. The association between SCTD and the BMI of each sex was analyzed separately by stratifying the data by SCTD type and regarding BMI as a categorical or as a continuous variable in different models. The odds ratio of SCTD was calculated from binary logistic regression models.Results: The prevalence of both subclinical hyperthyroidism and subclinical hypothyroidism was significantly lower in males compared to females. For subclinical hypothyroidism, we found no significant association with BMI in females. In males, there was a significant negative relationship between BMI and subclinical hypothyroidism. For subclinical hyperthyroidism, we did not find any significant relationship with BMI in either sex after stratifying the data and treating BMI as a categorical or as a continuous variable.Conclusion: For subclinical hyperthyroidism, no significant effect was found in either sex. For subclinical hypothyroidism, high BMI was associated with lower rates of subclinical hypothyroidism in males, and no significant correlation was found in females. The mechanism of this sex-specific association between BMI and SCTD needs more verification.Abbreviations: ALT = alanine aminotransferase; AST = aspartate aminotransferase; BMI = body mass index; BUN = blood urea nitrogen; CI = confidence interval; Cr = creatinine; DBP = diastolic blood pressure; FG = fasting glucose; FT3 = free triiodothyronine; FT4 = free thyroxine; HDL = high-density lipoprotein; LDL = low-density lipoprotein; OR = odds ratio; SBP = systolic blood pressure; SCTD = subclinical thyroid dysfunction; TBIL = total bilirubin; TC = total cholesterol; TG = triglyceride; TSH = thyroid-stimulating hormone; UA = uric acid; WBC = white blood cell; WC = waist circumference     

Associations between White Matter Microstructure and Cognitive Performance in Old and Very Old Age

Increasing age is associated with deficits in a wide range of cognitive domains as well as with structural brain changes. Recent studies using diffusion tensor imaging (DTI) have shown that microstructural integrity of white matter is associated with cognitive performance in elderly persons, especially on tests that rely on perceptual speed. We used structural equation modeling to investigate associations between white matter microstructure and cognitive functions in a population-based sample of elderly persons (age ≥ 60 years), free of dementia, stroke, and neurological disorders (n = 253). Participants underwent a magnetic resonance imaging scan, from which mean fractional anisotropy (FA) and mean diffusivity (MD) of seven white matter tracts were quantified. Cognitive functioning was analyzed according to performance in five task domains (perceptual speed, episodic memory, semantic memory, letter fluency, and category fluency). After controlling for age, FA and MD were exclusively related to perceptual speed. When further stratifying the sample into two age groups, the associations were reliable in the old-old (≥78 years) only. This relationship between white matter microstructure and perceptual speed remained significant after excluding persons in a preclinical dementia phase. The observed pattern of results suggests that microstructural white matter integrity may be especially important to perceptual speed among very old adults.     

Effects of Hydrogen-Rich Saline on Hepatectomy-Induced Postoperative Cognitive Dysfunction in Old Mice

This study aims to investigate the protective effects and underlying mechanisms of hydrogen-rich saline on the cognitive functions of elder mice with partial hepatectomy-induced postoperative cognitive dysfunction (POCD). Ninety-six old male Kunming mice were randomly divided into 4 groups (n?=?24 each): control group (group C), hydrogen-rich saline group (group H), POCD group (group P), and POCD?+?hydrogen-rich saline group (group PH). Cognitive function was subsequently assessed using Morris water-maze (MWM) test. TNF-α and IL-1β levels were measured by enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry, along with NF-κB activity determined by ELISA. The morphology of hippocampal tissues were further observed by HE staining. Learning and memory abilities of mice were significantly impaired at day 10 and day 14 post-surgery, as partial hepatectomy significantly prolonged the escape latency, decreased time at the original platform quadrant and frequency of crossing in group P when compared to group C (p?<?0.05). The surgery also increased the contents of TNF-α, IL-1β, and NF-κB activity at all time points after surgery (p?<?0.05). The introduction of hydrogen-rich saline (group PH) partially rescued spatial memory and learning as it shortened escape latency and increased time and crossing frequency of original platform compared to group P (p?<?0.05). Moreover, such treatment also decreased TNF-α and IL-1β levels and NF-κB activity (p?<?0.05). In addition, cell necrosis in the hippocampus induced by hepatectomy was also rescued by hydrogen-rich saline. Hydrogen-rich saline can alleviate POCD via inhibiting NF-κB activity in the hippocampus and reducing inflammatory response.     

Microvascular Dysfunction and Cognitive Impairment

The impact of vascular risk factors on cognitive function has garnered much interest in recent years. The appropriate distribution of oxygen, glucose, and other nutrients by the cerebral vasculature is critical for proper cognitive performance. The cerebral microvasculature is a key site of vascular resistance and a preferential target for small vessel disease. While deleterious effects of vascular risk factors on microvascular function are known, the contribution of this dysfunction to cognitive deficits is less clear. In this review, we summarize current evidence for microvascular dysfunction in brain. We highlight effects of select vascular risk factors (hypertension, diabetes, and hyperhomocysteinemia) on the pial and parenchymal circulation. Lastly, we discuss potential links between microvascular disease and cognitive function, highlighting current gaps in our understanding.