Developing blood-brain barrier arterial spin labelling as a non-invasive early biomarker of Alzheimer's disease (DEBBIE-AD): a prospective observational multicohort study protocol

INTRODUCTION

Loss of blood-brain barrier (BBB) integrity is hypothesised to be one of the earliest microvascular signs of Alzheimer's disease (AD). Existing BBB integrity imaging methods involve contrast agents or ionising radiation, and pose limitations in terms of cost and logistics. Arterial spin labelling (ASL) perfusion MRI has been recently adapted to map the BBB permeability non-invasively. The DEveloping BBB-ASL as a non-Invasive Early biomarker (DEBBIE) consortium aims to develop this modified ASL-MRI technique for patient-specific and robust BBB permeability assessments. This article outlines the study design of the DEBBIE cohorts focused on investigating the potential of BBB-ASL as an early biomarker for AD (DEBBIE-AD).

METHODS AND ANALYSIS

DEBBIE-AD consists of a multicohort study enrolling participants with subjective cognitive decline, mild cognitive impairment and AD, as well as age-matched healthy controls, from 13 cohorts. The precision and accuracy of BBB-ASL will be evaluated in healthy participants. The clinical value of BBB-ASL will be evaluated by comparing results with both established and novel AD biomarkers. The DEBBIE-AD study aims to provide evidence of the ability of BBB-ASL to measure BBB permeability and demonstrate its utility in AD and AD-related pathologies.

ETHICS AND DISSEMINATION

Ethics approval was obtained for 10 cohorts, and is pending for 3 cohorts. The results of the main trial and each of the secondary endpoints will be submitted for publication in a peer-reviewed journal.

Effect of Acetylcholinesterase Inhibitors on Cerebral Perfusion and Cognition: A Systematic Review

BACKGROUND

Perfusion imaging has the potential to identify neurodegenerative disorders in a preclinical stage. However, to correctly interpret perfusion-derived parameters, the impact of perfusion modifiers should be evaluated.

OBJECTIVE

In this systematic review, the impact of acute and chronic intake of four acetylcholinesterase inhibitors (AChEIs) on cerebral perfusion in adults was investigated: physostigmine, donepezil, galantamine, and rivastigmine.

RESULTS

Chronic AChEI treatment results in an increase of cerebral perfusion in treatment-responsive patients with Alzheimer's disease, dementia with Lewy bodies, and Parkinson's disease dementia in the frontal, parietal, temporal, and occipital lobes, as well as the cingulate gyrus. These effects appear to be temporary, dose-related, and consistent across populations and different AChEI types. On the contrary, further perfusion decline was reported in patients not receiving AChEIs or not responding to the treatment.

CONCLUSION

AChEIs appear to be a potential perfusion modifier in neurodegenerative patients. More research focused on quantitative perfusion in both patients with and without a cholinergic deficit is needed to draw conclusions on whether AChEI intake should be considered when analyzing perfusion data.

Subthreshold symptoms and obsessive-compulsive disorder: evaluating the diagnostic threshold

BACKGROUND

In this study we compared subjects with obsessive and/or compulsive symptoms who did not meet all criteria for obsessive-compulsive disorder (OCD) (subthreshold subjects) to subjects with full-blown OCD and also to subjects without obsessions or compulsions.

METHOD

The data were derived from the Netherlands Mental Health Survey and Incidence Study (NEMESIS), a large representative sample of the general Dutch population (n=7076). Using the Composite International Diagnostic Interview, Version 1.1 (CIDI 1.1), three groups were distinguished: subjects without lifetime obsessions or compulsions (94.2%), subthreshold subjects (4.9%) and subjects with full-blown OCD according to DSM-III-R (0.9%). These three groups were compared on various items, including psychological vulnerability, health and functional status, psychiatric co-morbidity and seeking treatment.

RESULTS

Subthreshold and OCD subjects had similar scores on the majority of the items measured. Thus, there was little difference between subthreshold and OCD subjects in health, functional status, psychological vulnerability and psychiatric co-morbidity. However, OCD and subthreshold subjects scored worse on most of these items when compared to the controls without obsessions or compulsions.

CONCLUSION

Having obsessions and compulsions is associated with substantial suffering and disability. Most subjects with obsessions and/or compulsions are not diagnosed with OCD according to the DSM-III-R criteria although these subjects generally display similar consequences to full-blown OCD subjects. We recommend that these subthreshold cases receive special attention in the development of DSM-V.