Lower Hippocampus Research Articles

Association between physical function and neuroimaging measures in a 2‐year multidomain lifestyle randomized controlled trial

AbstractBackgroundThis exploratory study investigated associations between physical function and neuroimaging biomarkers: brain magnetic resonance imaging (MRI) and Pittsburgh compound B‐positron emission tomography (PiB‐PET) measures during the 2‐year Finnish Geriatric Intervention Study to prevent cognitive impairment and disability (FINGER).MethodFINGER targeted 60–77‐year‐old general population at‐risk and without dementia or substantial cognitive impairment. Measures of physical function (activities of daily living (ADL), hand grip strength, physical performance, Fried’s frailty phenotype index and self‐rated health) from baseline and 2‐year visits were used. Baseline neuroimaging measures, MRI (hippocampus, total gray matter volumes, Alzheimer’s disease (AD) signature cortical thickness) were available for 115‐132 participants and PiB‐PET (composite score) for 44‐48 participants. Linear and logistic regressions were used to test the cross‐sectional associations and the impact of baseline imaging measures on changes in physical function. Models were adjusted for site, sex and education.ResultCross‐sectionally, higher ADL were associated with higher hippocampus volume (β = 0.18 p = 0.048), total gray matter volume (β = 0.15 p = 0.005) and AD signature cortical thickness (β = 0.25 p = 0.006) while stronger hand grip and was associated with higher total gray matter volume (β = 0.20 p = 0.041) significantly. Baseline imaging measures were associated with changes in physical function: higher baseline hippocampus volume was associated with maintenance/improvement in the ADL (OR = 0.56 p = 0.039) while lower hippocampus at baseline predicted poorer physical performance over time (OR = 1.66 p = 0.036).ConclusionHigher brain integrity is associated with better physical function while lower baseline brain integrity predicts poorer physical function over time.

Association between physical function and neuroimaging measures in a 2‐year multidomain lifestyle randomized controlled trial

AbstractBackgroundThis exploratory study investigated associations between physical function and neuroimaging biomarkers: brain magnetic resonance imaging (MRI) and Pittsburgh compound B‐positron emission tomography (PiB‐PET) measures during the 2‐year Finnish Geriatric Intervention Study to prevent cognitive impairment and disability (FINGER).MethodFINGER targeted 60–77‐year‐old general population at‐risk and without dementia or substantial cognitive impairment. Measures of physical function (activities of daily living (ADL), hand grip strength, physical performance, Fried’s frailty phenotype index and self‐rated health) from baseline and 2‐year visits were used. Baseline neuroimaging measures, MRI (hippocampus, total gray matter volumes, Alzheimer’s disease (AD) signature cortical thickness) were available for 115‐132 participants and PiB‐PET (composite score) for 44‐48 participants. Linear and logistic regressions were used to test the cross‐sectional associations and the impact of baseline imaging measures on changes in physical function. Models were adjusted for site, sex and education.ResultCross‐sectionally, higher ADL were associated with higher hippocampus volume (ß = 0.18 p = 0.048), total gray matter volume (ß = 0.15 p = 0.005) and AD signature cortical thickness (ß = 0.25 p = 0.006) while stronger hand grip and was associated with higher total gray matter volume (ß = 0.20 p = 0.041) significantly. Baseline imaging measures were associated with changes in physical function: higher baseline hippocampus volume was associated with maintenance/improvement in the ADL (OR = 0.56 p = 0.039) while lower hippocampus at baseline predicted poorer physical performance over time (OR = 1.66 p = 0.036).ConclusionHigher brain integrity is associated with better physical function while lower baseline brain integrity predicts poorer physical function over time.

Vascular determinants of hippocampal viscoelastic properties in healthy adults across the lifespan

Arterial stiffness and cerebrovascular pulsatility are non-traditional risk factors of Alzheimer’s disease. However, there is a gap in understanding the earliest mechanisms that link these vascular determinants to brain aging. Changes to mechanical tissue properties of the hippocampus (HC), a brain structure essential for memory encoding, may reflect the impact of vascular dysfunction on brain aging. We tested the hypothesis that arterial stiffness and cerebrovascular pulsatility are related to HC tissue properties in healthy adults across the lifespan. Twenty-five adults underwent measurements of brachial blood pressure (BP), large elastic artery stiffness, middle cerebral artery pulsatility index (MCAv PI), and magnetic resonance elastography (MRE), a sensitive measure of HC viscoelasticity. Individuals with higher carotid pulse pressure (PP) exhibited lower HC stiffness (β = −0.39, r = −0.41, p = 0.05), independent of age and sex. Collectively, carotid PP and MCAv PI significantly explained a large portion of the total variance in HC stiffness (adjusted R2 = 0.41, p = 0.005) in the absence of associations with HC volumes. These cross-sectional findings suggest that the earliest reductions in HC tissue properties are associated with alterations in vascular function.

Association of impaired lung function with dementia, and brain magnetic resonance imaging indices: a large population-based longitudinal study.

to examine the association between different patterns of impaired lung function with the incident risk of dementia and magnetic resonance imaging (MRI)-based brain structural features. in UK Biobank, a total of 308,534 dementia-free participants with valid lung function measures (forced expiratory volume in 1 s [FEV1] and forced vital capacity [FVC]) were included. Association was assessed using Cox proportional hazards regression model. Furthermore, the association between impaired lung function and brain MRI biomarkers related to cognitive function was analysed among 30,159 participants. during a median follow-up of 12.6years, 3,607 incident all-cause dementia cases were recorded. Restrictive impairment (hazard ratio [HR], 1.42; 95% confidence interval [CI], 1.27-1.60) and obstructive impairment (HR, 1.28; 95% CI, 1.15-1.42) were associated with higher risk of all-cause dementia. The restricted cubic splines indicated FEV1% predicted and FVC % predicted had reversed J-shaped associations with dementia. Participants with impaired lung function have higher risks of all-cause dementia across all apolipoprotein E (APOE) risk categories, whereas associations were stronger among those of low APOE risk (P for interaction = 0.034). In addition, restrictive and obstructive impairment were linked to lower total (β: -0.075, SE: 0.021, Pfdr = 0.002; β: -0.033, SE: 0.017, Pfdr = 0.069) and frontoparietal grey matter volumes, higher white matter hyperintensity, poorer white matter integrity, lower hippocampus (β: -0.066, SE: 0.024, Pfdr = 0.017; β: -0.051, SE: 0.019, Pfdr = 0.019) and other subcortical volumes. participants with restrictive and obstructive impairments had a higher risk of dementia. Brain MRI indices further supported adverse effects and provided insight into potential pathophysiology biomarkers.

Dosimetric comparison between intensity-modulated radiotherapy and volumetric-modulated arc therapy in hippocampus sparing in brain metastasis treated by whole-brain irradiation and simultaneous integrated boost

AbstractBackground:While treating brain metastasis with whole-brain radiotherapy incorporating a simultaneous integrated boost (WBRT-SIB), the risk of hippocampus injury is high. The aim of this study is to compare dosimetrically between intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) in sparing of hippocampus and organs at risk (OARs) and planning target volume (PTV) coverage.Methods:In total, 16 patients presenting with more than one brain metastases were previously treated and then retrospectively planned using VMAT and IMRT techniques. For each patient, a dual-arc VMAT and another IMRT (five beams) plans were created. For both techniques, 30 Gy in 10 fractions was prescribed to the whole brain (WB) minus the hippocampi and 45 Gy in 10 fractions to the tumour with 0·5 cm margin. Dose–volume histogram (DVH), conformity index (CI) and homogeneity index (HI) of PTV, hippocampus mean and maximum dose and other OARs for both techniques were calculated and compared.Results:A statistically significant advantage was found in WB-PTV CI and HI with VMAT, compared to IMRT. There were lower hippocampus mean and maximum doses in VMAT than IMRT. The maximum hippocampus dose ranged between 15·5 and 19·2 Gy and between 18·4 and 20·6 Gy in VMAT and IMRT, respectively. The mean dose of the hippocampus ranged between 11·5 and 17·7 Gy and between 13·2 and 18·3 Gy in VMAT and IMRT, respectively.Conclusion:Using WBRT-SIB technique, VMAT showed better PTV coverage with less mean and maximum doses to the hippocampus than IMRT. Clinical randomised studies are needed to confirm safety and clinical benefit of WBRT-SIB.

Smaller hippocampal volume in current but not in past depression in comparison to healthy controls: Minor evidence from an older adults sample

BackgroundStructural neuroimaging studies revealed a consistent pattern of volumetric reductions in both hippocampus (HC) and anterior cingulate cortex (ACC) of individuals with major depressive episode(s) (MDE). This study investigated HC and ACC volume differences in currently depressed individuals (n = 150), individuals with a past lifetime MDE history (n = 79) and healthy controls (n = 287). MethodsNon-demented individuals were recruited from a cohort of community-dwelling older adults (ESPRIT study). T1-weighted magnetic resonance images and FreeSurfer Software (automated method) were used. Concerning HC, a manual method of measurement dividing HC into head, body, and tail was also used. General Linear Model was applied adjusting for covariates. ResultsCurrent depression was associated with lower left posterior HC volume, using manual measurement, in comparison to healthy status. However, when we slightly changed sub-group inclusion criteria, results did not survive to correction for multiple comparisons. ConclusionsThe finding of lower left posterior HC volume in currently depressed individuals but not in those with a past MDE compared to healthy controls could be related to brain neuroplasticity. Additionally, our results may suggest manual measures to be more sensitive than automated methods.

Study on interference effect of Sijunzi decoction on brain-gut CaM/CaMKⅡ of spleen Qi deficiency syndrome rats

To observe the dynamic time-phase expressions of key genes of brain-gut CaM signal pathway of spleen Qi deficiency rats and the intervention effect of Sijunzi decoction.Male Wistar rats were randomly divided into the normal control group, model 14 d, 21 d, 28 d groups, and Sijunzi decoction 14 d, 21 d, 28 d groups. Except for the normal control group, the remaining groups were included into the spleen Qi deficiency model with the bitter cold breaking Qi method (ig 7.5 g · kg⁻¹ · d⁻¹ of Rheum officinale, Fructus aurantii immaturus, Magnolia officinalis preparation) and the exhaustive swimming method. On the 7th day after the modeling, the Sijunzi decoction groups were orally administered with Sijunzi decoction 20 g · kg⁻¹ · d⁻¹. The expressions of key genes CaM/CaMK II of CaM signaling pathway in hippocampus and intestine at different time points by immunohistochemical method and Western blot. At the same time, the intervention effect of Sijunzi decoction on spleen Qi deficiency rats and its mechanism were analyzed.Spleen Qi deficiency rats showed higher intestinal CaM/CaMK II expression and lower hippocampus CaM/CaMK II expression than normal rats (P < 0.05, P < 0.01). After the treatment of Sijunzi decoction, spleen Qi deficiency rats showed reduction in intestinal CaM/CaMK II expression and increase in hippocampus CaM/CaMK II expression (P < 0.05, P < 0.01).The formation of spleen Qi deficiency syndrome may be related to the high expression of CaM/CaMK II in small intestine tissues and its low expression in hippocampus tissues. Sijunzi decoction may achieve the therapeutic effect in spleen Qi deficiency syndrome by reducing the CaM/CaMK II expression in intestinal tissues and increasing it in hippocampus tissues.