Neural correlates of the revised reinforcement sensitivity theory: A cross-sectional structural neuroimaging study in middle-aged adults.

The revised reinforcement sensitivity theory (RST) proposes that neurobiological systems control behavior: the fight-flight-freeze (FFFS) for avoidance of threat; behavioral approach/activation (BAS) for approach to rewards; and behavioral inhibition (BIS) for conflict resolution when avoidance and approach are possible. Neuroimaging studies have confirmed some theoretical associations between brain structures and the BAS and BIS; however, little representative population data are available for the FFFS. We investigated the neural correlates of the revised RST in a sample of 404 middle-aged adults (M = 47.

A role for retro-splenial cortex in the task-related P3 network.

Objective: The P3 is an event-related response observed in relation to task-relevant sensory events. Despite its ubiquitous presence, the neural generators of the P3 are controversial and not well identified.

Methods: We compared source analysis of combined magneto- and electroencephalography (M/EEG) data with functional magnetic resonance imaging (fMRI) and simulation studies to better understand the sources of the P3 in an auditory oddball paradigm.

A role for retro-splenial cortex in the task-related P3 network.

Objective: The P3 is an event-related response observed in relation to task-relevant sensory events. Despite its ubiquitous presence, the neural generators of the P3 are controversial and not well identified.

Methods: We compared source analysis of combined magneto- and electroencephalography (M/EEG) data with functional magnetic resonance imaging (fMRI) and simulation studies to better understand the sources of the P3 in an auditory oddball paradigm.

Midsagittal corpus callosal thickness and cognitive impairment in Parkinson's disease.

People diagnosed with Parkinson's disease (PD) can experience significant neuropsychiatric symptoms, including cognitive impairment and dementia, the neuroanatomical substrates of which are not fully characterised. Symptoms associated with cognitive impairment and dementia in PD may relate to direct structural changes to the corpus callosum via primary white matter pathology or as a secondary outcome due to the degeneration of cortical regions. Using magnetic resonance imaging, the corpus callosum can be investigated at the midsagittal plane, where it converges to a contiguous mass and is not intertwined with other tracts.

Association between Type 2 Diabetes Mellitus and Brain Atrophy: A Meta-Analysis.

Background: Type 2 diabetes mellitus (T2DM) is known to be associated with cognitive decline and brain structural changes. This study systematically reviews and estimates human brain volumetric differences and atrophy associated with T2DM.

Methods: PubMed, PsycInfo and Cochrane Library were searched for brain imaging studies reporting on brain volume differences between individuals with T2DM and healthy controls.

Optimal Blood Pressure Keeps Our Brains Younger.

: Elevated blood pressure (BP) is a major health risk factor and the leading global cause of premature death. Hypertension is also a risk factor for cognitive decline and dementia. However, when elevated blood pressure starts impacting cerebral health is less clear.

Longitudinal Effects of Physical Activity Change on Hippocampal Volumes over up to 12 Years in Middle and Older Age Community-Dwelling Individuals.

The objectives of this study were to investigate the long-term associations between changes in physical activity levels and hippocampal volumes over time, while considering the influence of age, sex, and APOE-ε4 genotype. We investigated the effects of change in physical activity on hippocampal volumes in 411 middle age (mean age = 47.2 years) and 375 older age (mean age = 63.

Longitudinal trajectories of hippocampal volume in middle to older age community dwelling individuals.

Understanding heterogeneity in brain aging trajectories is important to estimate the extent to which aging outcomes can be optimized. Although brain changes in late life are well-characterized, brain changes in middle age are not well understood. In this study, we investigated hippocampal change in a generally healthy community-living population of middle (n = 421, mean age 47.

IMPARO: inferring microbial interactions through parameter optimisation.

Background: Microbial Interaction Networks (MINs) provide important information for understanding bacterial communities. MINs can be inferred by examining microbial abundance profiles. Abundance profiles are often interpreted with the Lotka Volterra model in research.

Volumetric brain differences in clinical depression in association with anxiety: a systematic review with meta-analysis.

Background: Structural differences associated with depression have not been confirmed in brain regions apart from the hippocampus. Comorbid anxiety has been inconsistently assessed, and may explain discrepancies in previous findings. We investigated the link between depression, comorbid anxiety and brain structure.

Objectively measured physical activity is associated with dorsolateral prefrontal cortex volume in older adults.

Background: Epidemiological studies suggest physical activity (PA) can slow or prevent both cognitive decline and age-related atrophy in frontal and hippocampal gray matter volumes. However, much of this evidence is based on self-reported measures of PA.

Methods: PA was measured objectively with a SenseWear™ Armband to examine the cross-sectional associations between the duration of light, moderate and vigorous intensity PA with gray matter volume in the dorsolateral prefrontal cortex (DLPFC) and hippocampus in 167 (female: 43%) cognitively healthy older adults aged 73 to 78.

Regional brain atrophy predicts time to conversion to Alzheimer's disease, dependent on baseline volume.

A key question for the design of clinical trials for Alzheimer's disease (AD) is whether the timing of conversion from mild cognitive impairment (MCI) to AD can be predicted. This is also an important question for the clinical management of MCI. This study aims to address this question by exploring the contribution of baseline brain volume and annual volume change, using Cox regression, in predicting the time to conversion.

Cognitive/Functional Measures Predict Alzheimer's Disease, Dependent on Hippocampal Volume.

Objectives: This study aimed to investigate the predictive value of cognitive/functional measures in combination with hippocampal volume (HCV) on the probability of conversion from mild cognitive impairment (MCI) to Alzheimer's disease (AD).

Methods: The Rey Auditory Verbal Learning Test for immediate memory, Mini-Mental State Examination, a functional assessment for independent daily activities and Alzheimer's Disease Assessment Scale were used as cognitive/functional measures and HCV as neuroimaging measure. Logistic regression and Cox proportional hazard analyses were used to explore the measures' predictive values for AD conversion and time to conversion.

Relationship Between Sulcal Characteristics and Brain Aging.

This study aimed to determine whether sulcal morphology differs between middle age (MA) and older healthy individuals. Furthermore, we sought to determine whether age-related differences in sulcal characteristics were more strongly associated with differences in local or global cortical volumes. Participants (age 44-50, = 403; age 64-70, = 390) from the Personality and Total Health Through Life (PATH) study were included.

Longitudinal Assessment of Hippocampal Atrophy in Midlife and Early Old Age: Contrasting Manual Tracing and Semi-automated Segmentation (FreeSurfer).

It is important to have accurate estimates of normal age-related brain structure changes and to understand how the choice of measurement technique may bias those estimates. We compared longitudinal change in hippocampal volume, laterality and atrophy measured by manual tracing and FreeSurfer (version 5.3) in middle age (n = 244, 47.

Higher fasting plasma glucose is associated with smaller striatal volume and poorer fine motor skills in a longitudinal cohort.

Previous studies have demonstrated associations between higher blood glucose and brain atrophy and functional deficits, however, little is known about the association between blood glucose, striatal volume and striatal function despite sensori-motor deficits being reported in diabetes. This study investigated the relationship between blood glucose levels, striatal volume and fine motor skills in a longitudinal cohort of cognitively healthy individuals living in the community with normal or impaired fasting glucose or type 2 diabetes. Participants were 271 cognitively healthy individuals (mean age 63 years at inclusion) with normal fasting glucose levels (<5.

A simple and clinically relevant combination of neuroimaging and functional indexes for the identification of those at highest risk of Alzheimer's disease.

The current challenge in clinical practice is to identify those with mild cognitive impairment (MCI), who are at greater risk of Alzheimer's disease (AD) conversion in the near future. The aim of this study was to assess a clinically practical new hippocampal index-hippocampal volume normalized by cerebellar volume (hippocampus to cerebellum volume ratio) used alone or in combination with scores on the Mini-Mental State Examination, as a predictor of conversion from MCI to AD. The predictive value of the HCCR was also contrasted to that of the hippocampal volume to intracranial volume ratio.

More highly myelinated white matter tracts are associated with faster processing speed in healthy adults.

The objective of this study was to investigate whether the estimated myelin content of white matter tracts is predictive of cognitive processing speed and whether such associations are modulated by age. Associations between estimated myelin content and processing speed were assessed in 570 community-living individuals (277 middle-age, 293 older-age). Myelin content was estimated in-vivo using the mean T1w/T2w magnetic resonance ratio, in six white matter tracts (anterior corona radiata, superior corona radiata, pontine crossing tract, anterior limb of the internal capsule, genu of the corpus callosum, and splenium of the corpus callosum).

Validated Alzheimer's Disease Risk Index (ANU-ADRI) is associated with smaller volumes in the default mode network in the early 60s.

Strong evidence is available suggesting that effective reduction of exposure to demonstrated modifiable risk factors in mid-life or before could significantly decrease the incidence of Alzheimer's disease (AD) and delay its onset. A key ingredient to achieving this goal is the reliable identification of individuals at risk well before they develop clinical symptoms. The aim of this study was to provide further neuroimaging evidence of the effectiveness of a validated tool, the ANU Alzheimer's Disease Risk Index, for the assessment of future risk of cognitive decline.

Increasing Body Mass Index at Midlife is Associated with Increased Cortical Thinning in Alzheimer's Disease-Vulnerable Regions.

Higher body mass index (BMI) at midlife is associated with greater decreases in cognitive function at older age as well as increased Alzheimer's disease (AD) risk, compared to those with normal BMI. Here, we tested whether BMI at midlife was associated with cortical thinning in brain regions known to be affected in early AD. We examined a large sample (n = 404) of midlife individuals (44-49 years) from the PATH population-based study.

The cerebellum shrinks faster than normal ageing in Alzheimer's disease but not in mild cognitive impairment.

Background: While acceleration in age-related cerebral atrophy has been well documented in Alzheimer's disease, the cerebellar contributions to this effect have not been thoroughly investigated.

Objective: This study investigated cerebellar volume and atrophy rate using magnetic resonance imaging in individuals with normal cognition (CN), mild cognitive impairment (MCI), and Alzheimer's disease (AD).

Methods: Two hundred twenty-nine CN, 398 MCI and 191 AD participants of stage I ADNI database with screening scans were evaluated for cerebellar volume.

Higher Fasting Plasma Glucose is Associated with Increased Cortical Thinning Over 12 Years: The PATH Through Life Study.

Recent evidence suggests that type 2 diabetes (T2D) is associated with accelerated brain ageing, consistent with the observation of increased risk of cognitive impairment and dementia in affected individuals. Even non-diabetic individuals with impaired fasting plasma glucose (IFG) levels have shown increased cerebral atrophy, compared to individuals with normal glucose levels. We tested whether longitudinal rates of age-related cortical thinning were associated with fasting plasma glucose levels in a large sample (n = 322) of early-old age individuals (60-66 years) who were scanned with magnetic resonance imaging (1.