Alzheimer’s disease accounts for approximately 50% to 80% of all causes of dementia. Co-existence of AD with other diseases causing dementia poses a diagnostic challenge, as we are still far from diagnosing AD accurately in order to manage it appropriately. Neuroimaging techniques, not only help diagnose AD but also consistently feature in diagnostic and research criteria for AD as biomarkers. Molecular biomarkers including positron emission tomography (PET) and single-photon emission computed tomography (SPECT), and structural biomarkers including magnetic resonance imaging (MRI), have been used in various therapeutic and prognostic studies in AD. This review highlights the recent advances in neuroimaging biomarkers, including molecular biomarkers (PET and SPECT tracers) and structural biomarkers (MRI), for AD. For the purpose of this review, molecular biomarkers have been further subcategorized into non-specific radiotracers (FDG-PET and blood flow SPECT) and specific amyloid- and tau-related radiotracers. The aim of this review is to discuss the recent advances and evidence of molecular and structural biomarkers of AD.

Alzheimer’s disease accounts for approximately 50% to 80% of all causes of dementia. Co-existence of AD with other diseases causing dementia poses a diagnostic challenge as we are still far from diagnosing AD accurately and hence to manage it appropriately. Neuroimaging techniques, not only help diagnose AD but also consistently features in diagnostic and research criteria for AD as biomarkers. Molecular biomarkers including Positron emission tomography (PET) and Single Photon emission computed tomography (SPECT) and structural biomarkers including Magnetic Resonance Imaging (MRI) have been used in various therapeutic and prognostic studies in AD. This review highlights the recent advances in the neuroimaging biomarkers including molecular biomarkers (PET and SPECT) and structural biomarkers (MRI) for AD. For the purpose of this review, molecular biomarkers have been further subcategorized into non-specific radiotracers (FDG-PET and SPECT) and specific amyloid and tau related radiotracers. The aim of this review is to discuss the recent advances and evidences on molecular and structural biomarkers of AD.

Preserved late-life brain volume is associated with resilience to dementia. We examined relationships between birthweight, socioeconomic status and adult health with late-life brain volumes. We hypothesised that early-life factors have direct and indirect effects on the aging brain. Neurotypical adults aged 61-67y underwent MRI and brain volumes measured. Birthweight, health and socioeconomic status were assessed by historical data or contemporary assessment. Measures of health and socioeconomic status were extracted using principal component analysis. Relationships between variables were explored by linear regression and structural equation models. Birthweight (β=0.095, p=0.017, n=280) and childhood socioeconomic status (β=0.091, p=0.033, n=280) were directly associated with late-life brain volume. Childhood socioeconomic status was associated with additional increase in grey matter volume (β=0.04, p=0.047, n=280). Better adult health was linked to increased late-life brain volume (β=0.15, p=0.003, n=280). Birthweight and childhood socioeconomic status are associated with whole and regional brain volume through direct and indirect mechanisms. Optimal fetal development, good adult health and reduced poverty, may prevent brain atrophy and decrease dementia risk in late-life.

Haemoglobin concentrations decrease with age. Abnormally low and high haemoglobin concentrations are associated with reduced cognition; however, the evidence for these associations in cohort data is limited. This study aims to assess the relationship between haemoglobin concentration and cognition in a well-characterised cohort of older adults. Two hundred and fifty-two healthy participants were drawn from the Aberdeen Children of the 1950s cohort, aged between 59 to 65 years. Participants underwent cognitive tests of processing speed, memory, verbal and nonverbal reasoning, and language ability and these were used to construct a global cognitive score, g, using principal component analysis. Haemoglobin concentration in the blood was measured concurrently. Hierarchical multiple regression models were constructed assessing the relationship between haemoglobin concentration and each cognitive measure and these were corrected for age, sex, education, C-reactive protein, hypertension, and body mass index. Significant linear association between haemoglobin concentration and nonverbal reasoning demonstrated that low haemoglobin levels are associated with lower scores. A quadratic relationship was found for haemoglobin concentration and immediate memory scores in which low and high haemoglobin levels were associated with lower scores. Haemoglobin concentration was found to have a significant linear association with nonverbal reasoning scores and a significant quadratic association with memory scores. The results from this study help to understand the association between haemoglobin and different aspects of cognition.