Lorazepam Challenge for Individuals at Varying Genetic Risk for Alzheimer Disease

The effect of apolipoprotein E genotype on spatial processing in humans: A meta-analysis and systematic review

The ε4 allele of the apolipoprotein E (APOE4) gene is an established risk factor for Alzheimer's disease but its impact on cognition in healthy adults across the lifespan is unclear. One cognitive domain that is affected early in the course of Alzheimer's disease is spatial cognition, yet the evidence for APOE-related changes in spatial cognition is mixed. In this meta-analysis we assessed the impact of carrying the APOE4 allele on five subdomains of spatial cognition across the lifespan. We included studies of healthy human participants where an APOE4-carrier group (heterozygous or homozygous) could be compared to a homozygous group of APOE3-carriers. We identified 156 studies in total from three databases (Pubmed, Scopus and Web of Science) as well as through searching cited literature and contacting authors for unpublished data. 122 studies involving 32,547 participants were included in a meta-analysis, and the remaining studies are included in a descriptive review. APOE4 carriers scored significantly lower than APOE3 carriers (θˆ = -.08 [-.14, -.02]) on tests of spatial long-term memory; this effect was very small and was not modulated by age. On other subdomains of spatial cognition (spatial construction, spatial working memory, spatial reasoning, navigation) there were no effects of genotype. Overall, our results demonstrate that the APOE4 allele exerts little influence on spatial cognitive abilities in healthy adults.

Benzodiazepine-induced anterograde amnesia: detrimental side effect to novel study tool

Benzodiazepines (BZDs) are anxiolytic drugs that act on GABAa receptors and are used to treat anxiety disorders. However, these drugs come with the detrimental side effect of anterograde amnesia, or the inability to form new memories. In this review we discuss, behavioral paradigms, sex differences and hormonal influences affecting BZD-induced amnesia, molecular manipulations, including the knockout of GABAa receptor subunits, and regional studies utilizing lesion and microinjection techniques targeted to the hippocampus and amygdala. Additionally, the relationship between BZD use and cognitive decline related to Alzheimer's disease is addressed, as there is a lack of consensus on whether these drugs are involved in inducing or accelerating pathological cognitive deficits. This review aims to inspire new research directions, as there is a gap in knowledge in understanding the cellular and molecular mechanisms behind BZD-induced amnesia. Understanding these mechanisms will allow for the development of alternative treatments and potentially allow BZDs to be used as a novel tool to study Alzheimer's disease.

Repurposed agents in the Alzheimer's disease drug development pipeline

BACKGROUND

Treatments are needed to address the growing prevalence of Alzheimer's disease (AD). Clinical trials have failed to produce any AD drugs for Food and Drug Administration (FDA) approval since 2003, and the pharmaceutical development process is both time-consuming and costly. Drug repurposing provides an opportunity to accelerate this process by investigating the AD-related effects of agents approved for other indications. These drugs have known safety profiles, pharmacokinetic characterization, formulations, doses, and manufacturing processes.

METHODS

We assessed repurposed AD therapies represented in Phase I, Phase II, and Phase III of the current AD pipeline as registered on ClinicalTrials.gov as of February 27, 2020.

RESULTS

We identified 53 clinical trials involving 58 FDA-approved agents. Seventy-eight percent of the agents in trials had putative disease-modifying mechanisms of action. Of the repurposed drugs in the pipeline 20% are hematologic-oncologic agents, 18% are drugs derived from cardiovascular indications, 14% are agents with psychiatric uses, 12% are drug used to treat diabetes, 10% are neurologic agents, and the remaining 26% of drugs fall under other conditions. Intellectual property strategies utilized in these programs included using the same drug but altering doses, routes of administration, or formulations. Most repurposing trials were supported by Academic Medical Centers and were not funded through the biopharmaceutical industry. We compared our results to a European trial registry and found results similar to those derived from ClinicalTrials.gov.

CONCLUSIONS

Drug repurposing is a common approach to AD drug development and represents 39% of trials in the current AD pipeline. Therapies from many disease areas provide agents potentially useful in AD. Most of the repurposed agents are generic and a variety of intellectual property strategies have been adopted to enhance their economic value.