The time for multiple biomarkers in studies of cognitive aging and dementia is now

Associations of β-Amyloid and Vascular Burden With Rates of Neurodegeneration in Cognitively Normal Members of the 1946 British Birth Cohort

BACKGROUND AND OBJECTIVES

The goals of this work were to quantify the independent and interactive associations of β-amyloid (Aβ) and white matter hyperintensity volume (WMHV), a marker of presumed cerebrovascular disease (CVD), with rates of neurodegeneration and to examine the contributions of APOE ε4 and vascular risk measured at different stages of adulthood in cognitively normal members of the 1946 British Birth Cohort.

METHODS

Participants underwent brain MRI and florbetapir-Aβ PET as part of Insight 46, an observational population-based study. Changes in whole-brain, ventricular, and hippocampal volume were directly measured from baseline and repeat volumetric T1 MRI with the boundary shift integral. Linear regression was used to test associations with baseline Aβ deposition, baseline WMHV, APOE ε4, and office-based Framingham Heart Study Cardiovascular Risk Score (FHS-CVS) and systolic blood pressure (BP) at ages 36, 53, and 69 years.

RESULTS

Three hundred forty-six cognitively normal participants (mean [SD] age at baseline scan 70.5 [0.6] years; 48% female) had high-quality T1 MRI data from both time points (mean [SD] scan interval 2.4 [0.2] years). Being Aβ positive at baseline was associated with 0.87-mL/y faster whole-brain atrophy (95% CI 0.03, 1.72), 0.39-mL/y greater ventricular expansion (95% CI 0.16, 0.64), and 0.016-mL/y faster hippocampal atrophy (95% CI 0.004, 0.027), while each 10-mL additional WMHV at baseline was associated with 1.07-mL/y faster whole-brain atrophy (95% CI 0.47, 1.67), 0.31-mL/y greater ventricular expansion (95% CI 0.13, 0.60), and 0.014-mL/y faster hippocampal atrophy (95% CI 0.006, 0.022). These contributions were independent, and there was no evidence that Aβ and WMHV interacted in their effects. There were no independent associations of APOE ε4 with rates of neurodegeneration after adjustment for Aβ status and WMHV, no clear relationships between FHS-CVS or systolic BP and rates of neurodegeneration when assessed across the whole sample, and no evidence that FHS-CVS or systolic BP acted synergistically with Aβ.

DISCUSSION

Aβ and presumed CVD have distinct and additive effects on rates of neurodegeneration in cognitively normal elderly. These findings have implications for the use of MRI measures as biomarkers of neurodegeneration and emphasize the importance of risk management and early intervention targeting both pathways.

Situational expectations and surveillance in families affected by dementia: organising uncertainties of ageing and cognition

Recent political processes have rendered people with dementia an increasingly surveilled population. Surveillance is a contentious issue within dementia research, spanning technological monitoring, biomarker research and epidemiological data gathering. This paper explores surveillance in the relationships of people affected by dementia, how older relatives both with and without diagnoses are surveilled in everyday interactions, and the importance of expectations in guiding surveillance. This paper presents data from 41 in-depth interviews with people affected by dementia living in the community in the United Kingdom. Agedness was a key contributor to expectations that a person may have dementia, based on previous experiences, media accounts and wider awareness. Expectations provoked surveillance in interactions, with participants looking for signs of dementia when interacting with older relatives. Older people also enacted self-surveillance, monitoring their own behaviour. Various actions could be attributed to dementia because interpretation is malleable, partly vindicating expectations while leaving some uncertainties. Expectant surveillance transformed people's experiences because they organised their own actions, and interpreted those of others, in line with pre-existing meanings. The ability to interpret behaviours to fit expectations can bring coherence to uncertainties of ageing, cognition and dementia, but risks ascribing dementia to many older people who straddle those uncertainties.

Regulatory and Developmental Aspects of Biomarkers in the Treatment of Ocular Surface Disease

The ideal biomarker would be a simple laboratory or clinical evaluation before treatment, which would predict subsequent therapeutic response. This might include selection of which patients might respond to that treatment. While other disciplines such as neurology and oncology have biomarkers, ophthalmology is limited to one-elevated intraocular pressure as a surrogate for progressive glaucomatous field loss. US law in 2016 required the Food and Drug Administration (FDA) to set up a system to qualify biomarkers. The system now exists-with most validated or pending biomarkers limited to safety and infection. The American Academy of Ophthalmology selected dry eye disease as one of three diseases in which to standardize outcomes in ophthalmology research. There have been a number of biomarkers proposed for evaluating ocular surface disease and its treatment. None currently meets the scientific or regulatory basis for being a valid biomarker-however, additional research may result in validity. Given the FDA's scientific basis, it is unlikely that an unproven biomarker could be used for regulatory approval, even for a "SubPart H" conditional new drug application. Elsewhere in ophthalmology, we know that even patients who share the same disease gene or mutation may differ substantially in penetrance and clinical expression. Thus, it is not unexpected that ocular surface disease, a heterogeneous disease with a variable presentation of signs and symptoms, has yet to have validated biomarkers that reach the level of evidence that allows their use for diagnosis, prognosis, therapy, and for making decisions in drug development.