Sex-specific composite scales for longitudinal studies of incipient Alzheimer's disease

Maximizing utility of neuropsychological measures in sex-specific predictive models of incident Alzheimer's disease in the Framingham Heart Study

INTRODUCTION

Sex differences in neuropsychological (NP) test performance might have important implications for the diagnosis of Alzheimer's disease (AD). This study investigates sex differences in neuropsychological performance among individuals without dementia at baseline.

METHODS

Neuropsychological assessment data, both standard test scores and process coded responses, from Framingham Heart Study participants were analyzed for sex differences using regression model and Cox proportional hazards model. Optimal NP profiles were identified by machine learning methods for men and women.

RESULTS

Sex differences were observed in both summary scores and composite process scores of NP tests in terms of adjusted means and their associations with AD incidence. The optimal NP profiles for men and women have 10 and 8 measures, respectively, and achieve 0.76 mean area under the curve for AD prediction.

DISCUSSION

These results suggest that NP tests can be leveraged for developing more sensitive, sex-specific indices for the diagnosis of AD.

Anticholinergic Drug Burden and Neurocognitive Performance in the Study of Latinos-Investigation of Neurocognitive Aging

BACKGROUND

Studies of cumulative anticholinergic drug burden on cognitive function and impairment are emerging, yet few for Hispanics/Latinos.

OBJECTIVE

To examine associations between anticholinergic use and neurocognitive performance outcomes among diverse Hispanics/Latinos.

METHODS

This prospective cohort study included diverse Hispanic/Latino participants, enrolled in the Study of Latinos-Investigation of Neurocognitive, from New York, Chicago, Miami, and San Diego (n = 6,249). Survey linear regression examined associations between anticholinergic use (measured during baseline [Visit 1] and average 7-year follow up [Visit 2]) with global cognition, episodic learning, memory, phonemic fluency, processing speed, executive functioning, and average 7-year change.

RESULTS

Anticholinergic use was associated with lower cognitive global cognition (β= -0.21; 95% CI [-0.36; -0.05]), learning (β= -0.27; 95% CI [-0.47; -0.07]), memory (β= -0.22; 95% CI [-0.41; -0.03]), and executive functioning (β= -0.22; 95% CI [-0.40; -0.03]) scores, particularly among those who took anticholinergics at both visits. Anticholinergic use was associated with faster decline in global cognition, learning, and verbal fluency (β: -0.28 [95% CI: -0.55, -0.01]; β: -0.28 [95% CI: -0.55, -0.01]; β: -0.25, [95% CI -0.47, -0.04], respectively). Sex modified associations between anticholinergic use with global cognition, learning, and executive functioning (F3 = 3.59, F3 = 2.84, F3 = 3.88, respectively).

CONCLUSION

Anticholinergic use was associated with lower neurocognitive performance, especially among those who used anticholinergics at both visits, among a study population of diverse Hispanics/Latinos. Findings will support evidence-based decisions regarding anticholinergic prescriptions and efforts to minimize cognitive impact.

Enhancing the Sensitivity of Memory Tests: Reference Data for the Free and Cued Selective Reminding Test and the Logical Memory Task from Cognitively Healthy Subjects with Normal Alzheimer's Disease Cerebrospinal Fluid Biomarker Levels

BACKGROUND

Cognitive performance of a given individual should be interpreted in the context of reference standards obtained in cognitively healthy populations. Recent evidence has shown that removing asymptomatic individuals with biomarker evidence of Alzheimer's disease pathology from normative samples increases the sensitivity of norms to detect memory impairments. These kind of norms may be useful for defining subtle cognitive decline, the transitional cognitive decline between normal cognition and mild cognitive impairment.

OBJECTIVE

The present study aims to provide norms for the Free and Cued Selective Reminding Test (FCSRT) and the Logical Memory subtest of the Wechsler Memory Scale-IV in a sample of individuals aged 50-70 years with normal levels of amyloid-β and tau cerebrospinal fluid (CSF) biomarkers.

METHODS

The sample was composed of 248 individuals from the ALFA+ study with negative amyloid-β and tau CSF biomarker levels. Regression-based norms were developed, including adjustments for age, education, and sex when applicable.

RESULTS

We found that education was associated with the performance in all the variables of both tests while age had a marginal effect only in the delayed free recall of the FCSRT. Sex was also related to the performance in the FCSRT, with women outperforming men. Equations to calculate z-scores and normative percentile tables were created. As compared with previously published norms the reference data presented were more sensitive but less specific, as expected.

CONCLUSION

The use of the norms provided in this work, in combination with the already published conventional norms, may contribute to detecting subtle memory impairment.

Accelerating Alzheimer's disease drug discovery and development: what's the way forward?

Introduction: As the global burden of Alzheimer's disease (AD) grows, an effective disease-modifying therapy remains a distant prospect following the repeated failure of multiple therapeutics targeting β-amyloid and (it seems) tau over many years of costly effort. The repeated failure of single-target therapies to meaningfully modify disease progression raises major questions about the validity of many aspects of drug development in this area, especially target selection.Area covered: The authors explore the critical questions raised by a review of the collective experience to date, relating to why findings with non-clinical models and clinical biomarkers so frequently fail to translate to positive outcomes in clinical trials, which alternatives should be considered, and how we can design and conduct clinical trials that can successfully identify and quantify meaningful benefits in the future.Expert opinion: It is our opinion that we must recognize and accept the need to consider less specific, more multimodal approaches to addressing neurodegeneration in AD if we are to make progress - and we must avoid repeating the well intentioned, but ultimately erroneous, assumptions of the past.

Verbal memory dysfunction is associated with alterations in brain transcriptome in dominant temporal lobe epilepsy

OBJECTIVE

Memory dysfunction is prevalent in many neurological disorders and can have a significant negative impact on quality of life. The genetic contributions to memory impairment in epilepsy, particularly temporal lobe epilepsy (TLE), remain poorly understood. Here, we compare the brain transcriptome between TLE patients with and without verbal memory impairments to identify genes and signaling networks important for episodic memory.

METHODS

Brain tissues were resected from 23 adults who underwent dominant temporal lobectomy for treatment of pharmacoresistant epilepsy. To control for potential effects of APOE on memory, only those homozygous for the APOE ε3 allele were included. A battery of memory tests was performed, and patients were stratified into two groups based on preoperative memory performance. The groups were well matched on demographic and disease-related variables. Total RNA-Seq and small RNA-Seq were performed on RNA extracted from the brain tissues. Pathway and integrative analyses were subsequently performed.

RESULTS

We identified 1092 differentially expressed transcripts (DETs), with the majority (71%) being underexpressed in brain tissues from patients with impaired memory compared to those from patients with intact memory. Enrichment analysis revealed overrepresentation of genes in pathways pertaining to brain-related neurological dysfunction, including a subset associated with neurodegenerative diseases, memory, and cognition (APP, MAPT, PINK1). Despite including patients with identical APOE genotypes, we identify APOE as a differentially expressed gene associated with memory status. Small RNA-Seq identified four differentially expressed microRNAs (miRNAs) that were predicted to target a subset (22%) of all DETs. Integrative analysis showed that these miRNA-predicted DET targets impact brain-related pathways and biological processes also pertinent to memory and cognition.

SIGNIFICANCE

TLE-associated memory status may be influenced by differences in gene expression profiles within the temporal lobe. Upstream processes influencing differential expression signatures, such as miRNAs, could serve as biomarkers and potential treatment targets for memory impairment in TLE.