Do patients with young onset Alzheimer's disease deteriorate faster than those with late onset Alzheimer's disease? A review of the literature

Greater baseline cortical atrophy in the dorsal attention network predicts faster clinical decline in Posterior Cortical Atrophy

Background and Objectives

Posterior Cortical Atrophy (PCA) is a clinical syndrome characterized by progressive visuospatial and visuoperceptual impairment. As the neurodegenerative disease progresses, patients lose independent functioning due to the worsening of initial symptoms and development of symptoms in other cognitive domains. The timeline of clinical progression is variable across patients, and the field currently lacks robust methods for prognostication. Here, evaluated the utility of MRI-based cortical atrophy as a predictor of longitudinal clinical decline in a sample of PCA patients.

Methods

PCA patients were recruited through the Massachusetts General Hospital Frontotemporal Disorders Unit PCA Program. All patients had cortical thickness estimates from baseline MRI scans, which were used to predict longitudinal change in clinical impairment assessed by the CDR Sum-of-Boxes (CDR-SB) score. Multivariable linear regression was used to estimate the magnitude of cortical atrophy in PCA patients relative to a group of amyloid-negative cognitively unimpaired participants. Linear mixed-effects models were used to test hypotheses about the utility of baseline cortical atrophy for predicting longitudinal clinical decline.

Results

Data acquired from 34 PCA patients (mean age = 65.41 ± 7.90, 71% females) and 24 controls (mean age = 67.34 ± 4.93, 50% females) were analyzed. Sixty-two percent of the PCA patients were classified as having mild cognitive impairment (CDR 0.5) at baseline, with the rest having mild dementia (CDR 1). Each patient had at least one clinical follow-up, with the mean duration of 2.78 ± 1.62 years. Relative to controls, PCA patients showed prominent baseline atrophy in the posterior cortical regions, with the largest effect size observed in the visual network of the cerebral cortex. Cortical atrophy localized to the dorsal attention network, which supports higher-order visuospatial function, selectively predicted the rate of subsequent clinical decline.

Discussion

These results demonstrate the utility of a snapshot measure of cortical atrophy of the dorsal attention network for predicting the rate of subsequent clinical decline in PCA. If replicated, this topographically-specific MRI-based biomarker could be useful as a clinical prognostication tool that facilitates personalized care planning.

Correlation between serum biomarkers, brain volume, and retinal neuronal loss in early-onset Alzheimer's disease

PURPOSE

To compare the peripapillary retinal nerve fiber layer (pRNFL), retinal nerve fiber layer (RNFL), and ganglion cell complex (GCC) thickness measurement in early-onset Alzheimer's disease (EOAD) and controls using spectral domain optical coherence tomography (SD-OCT). We also assessed the relationship between SD-OCT measurements and cognitive measures, serum biomarkers for Alzheimer's disease (AD), and cerebral microstructural volume.

METHODS

pRNFL, RNFL, and GCC thicknesses were measured in 43 EOAD and 42 controls using SD-OCT. Montreal Cognitive Assessment (MoCA) and Mini-Mental State Examination (MMSE) were used to assess cognitive status, magnetic resonance imaging (MRI) tool was used to quantify cerebral microstructural volume, and serum biomarkers were quantified from peripheral blood.

RESULTS

EOAD patients had thinner pRNFL (P < 0.001), RNFL (P = 0.008), and GCC (P = 0.018) thicknesses compared to controls after adjusting for multiple factors. pRNFL thickness correlated (P = 0.016) with serum t-tau level. Serum Aβ42 (P < 0.05) concentration correlated with RNFL thickness. Importantly, occipital lobe volume (P = 0.010) correlated with GCC thicknesses in EOAD patients.

CONCLUSION

Our findings suggest that retinal thickness may be useful markers for assessing neurodegenerative process in EOAD.

Default mode network tau predicts future clinical decline in atypical early Alzheimer's disease

Identifying individuals with early stage Alzheimer's disease (AD) at greater risk of steeper clinical decline would allow professionals and loved ones to make better-informed medical, support, and life planning decisions. Despite accumulating evidence on the clinical prognostic value of tau PET in typical late-onset amnestic AD, its utility in predicting clinical decline in individuals with atypical forms of AD remains unclear. In this study, we examined the relationship between baseline tau PET signal and the rate of subsequent clinical decline in a sample of 48 A+/T+/N+ patients with mild cognitive impairment or mild dementia due to AD with atypical clinical phenotypes (Posterior Cortical Atrophy, logopenic variant Primary Progressive Aphasia, and amnestic syndrome with multi-domain impairment and age of onset < 65 years). All patients underwent structural magnetic resonance imaging (MRI), tau (18F-Flortaucipir) PET, and amyloid (either 18F-Florbetaben or 11C-Pittsburgh Compound B) PET scans at baseline. Each patient's longitudinal clinical decline was assessed by calculating the annualized change in the Clinical Dementia Rating Sum-of-Boxes (CDR-SB) scores from baseline to follow-up (mean time interval = 14.55 ± 3.97 months). Our sample of early atypical AD patients showed an increase in CDR-SB by 1.18 ± 1.25 points per year: t(47) = 6.56, p < .001, d = 0.95. These AD patients showed prominent baseline tau burden in posterior cortical regions including the major nodes of the default mode network, including the angular gyrus, posterior cingulate cortex/precuneus, and lateral temporal cortex. Greater baseline tau in the broader default mode network predicted faster clinical decline. Tau in the default mode network was the strongest predictor of clinical decline, outperforming baseline clinical impairment, tau in other functional networks, and the magnitude of cortical atrophy and amyloid burden in the default mode network. Overall, these findings point to the contribution of baseline tau burden within the default mode network of the cerebral cortex to predicting the magnitude of clinical decline in a sample of atypical early AD patients one year later. This simple measure based on a tau PET scan could aid the development of a personalized prognostic, monitoring, and treatment plan tailored to each individual patient, which would help clinicians not only predict the natural evolution of the disease but also estimate the effect of disease-modifying therapies on slowing subsequent clinical decline given the patient's tau burden while still early in the disease course.

Feasibility of Identifying Factors Related to Alzheimer's Disease and Related Dementia in Real-World Data

A comprehensive view of factors associated with AD/ADRD will significantly aid in studies to develop new treatments for AD/ADRD and identify high-risk populations and patients for prevention efforts. In our study, we summarized the risk factors for AD/ADRD by reviewing existing meta-analyses and review articles on risk and preventive factors for AD/ADRD. In total, we extracted 477 risk factors in 10 categories from 537 studies. We constructed an interactive knowledge map to disseminate our study results. Most of the risk factors are accessible from structured Electronic Health Records (EHRs), and clinical narratives show promise as information sources. However, evaluating genomic risk factors using RWD remains a challenge, as genetic testing for AD/ADRD is still not a common practice and is poorly documented in both structured and unstructured EHRs. Considering the constantly evolving research on AD/ADRD risk factors, literature mining via NLP methods offers a solution to automatically update our knowledge map.

[Features of the clinical and neuroimaging picture in patients with early-onset Alzheimer's disease]

The most common cause of severe cognitive impairment in adults is Alzheimer's disease (AD). Depending on the age of onset, AD is divided into early (<65 years) and late (≥65 years) forms. Early-onset AD (EOAD) is significantly less common than later-onset AD (LOAD) and accounts for only about 5-10% of cases. However, its medical and social significance, as a disease leading to loss of ability to work and legal capacity, as well as premature death in patients aged 40-64 years, is extremely high. Patients with EOAD compared with LOAD have a greater number of atypical clinical variants - 25% and 6-12.5%, respectively, which complicates the differential diagnosis of EOAD with other neurodegenerative diseases. However, the typical classical amnestic variant predominates in both EOAD and LOAD. Also, patients with EOAD have peculiarities according to neuroimaging data: when performing MRI of the brain, patients with EOAD often have more pronounced parietal atrophy and less pronounced hippocampal atrophy compared to patients with LOAD. The article pays attention to the features of the clinical and neuroimaging data in patients with EOAD; a case of a patient with EOAD is presented.

Neprilysin inhibitors and risk of Alzheimer's disease: A future perspective

Alzheimer's disease (AD) is a heterogeneous neurodegenerative disease with multifaceted neuropathological disorders. AD is characterized by intracellular accumulation of phosphorylated tau proteins and extracellular deposition of amyloid beta (Aβ). Various protease enzymes, including neprilysin (NEP), are concerned with the degradation and clearance of Aβ. Indeed, a defective neuronal clearance pathway due to the dysfunction of degradation enzymes might be a possible mechanism for the accumulation of Aβ and subsequent progression of AD neuropathology. NEP is one of the most imperative metalloproteinase enzymes involved in the clearance of Aβ. This review aimed to highlight the possible role of NEP inhibitors in AD. The combination of sacubitril and valsartan which is called angiotensin receptor blocker and NEP inhibitor (ARNI) may produce beneficial and deleterious effects on AD neuropathology. NEP inhibitors might increase the risk of AD by the inhibition of Aβ clearance, and increase brain bradykinin (BK) and natriuretic peptides (NPs), which augment the pathogenesis of AD. These verdicts come from animal model studies, though they may not be applied to humans. However, clinical studies revealed promising safety findings regarding the use of ARNI. Moreover, NEP inhibition increases various neuroprotective peptides involved in inflammation, glucose homeostasis and nerve conduction. Also, NEP inhibitors may inhibit dipeptidyl peptidase 4 (DPP4) expression, ameliorating insulin and glucagon-like peptide 1 (GLP-1) levels. These findings proposed that NEP inhibitors may have a protective effect against AD development by increasing GLP-1, neuropeptide Y (NPY) and substance P, and deleterious effects by increasing brain BK. Preclinical and clinical studies are recommended in this regard.

An updated overview of recent and ongoing deep brain stimulation (DBS) trials in patients with dementia: a systematic review

BACKGROUND

Dementia affects more than 55 million people worldwide. Several technologies have been developed to slow cognitive decline: deep brain stimulation (DBS) of network targets in Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) have been recently investigated.

OBJECTIVE

This study aimed to review the characteristics of the populations, protocols, and outcomes of patients with dementia enrolled in clinical trials investigating the feasibility and efficacy of DBS.

MATERIALS AND METHODS

A systematic search of all registered RCTs was performed on Clinicaltrials.gov and EudraCT, while a systematic literature review was conducted on PubMed, Scopus, Cochrane, and APA PsycInfo to identify published trials.

RESULTS

The literature search yielded 2122 records, and the clinical trial search 15 records. Overall, 17 studies were included. Two of 17 studies were open-label studies reporting no NCT/EUCT code and were analysed separately. Of 12 studies investigating the role of DBS in AD, we included 5 published RCTs, 2 unregistered open-label (OL) studies, 3 recruiting studies, and 2 unpublished trials with no evidence of completion. The overall risk of bias was assessed as moderate-high. Our review showed significant heterogeneity in the recruited populations regarding age, disease severity, informed consent availability, inclusion, and exclusion criteria. Notably, the standard mean of overall severe adverse events was moderately high (SAEs: 9.10 ± 7.10%).

CONCLUSION

The population investigated is small and heterogeneous, published results from clinical trials are under-represented, severe adverse events not negligible, and cognitive outcomes uncertain. Overall, the validity of these studies requires confirmation based on forthcoming higher-quality clinical trials.

Clinical characteristics of early-onset versus late-onset Alzheimer's disease: a systematic review and meta-analysis

OBJECTIVES

A number of studies have compared Alzheimer's disease (AD), the commonest form of dementia, based on their age of onset, i.e. before the age of 65 years (early-onset AD, EO-AD) to those developing after 65 years of age (late-onset AD, LO-AD), but the differences are not clear. We performed a systematic review and meta-analysis to compare clinical characteristics between EO-AD and LO-AD.

DESIGN, MEASUREMENTS, AND PARTICIPANTS

Medline, Embase, PsycINFO, and CINAHL databases were systematically searched for studies comparing time to diagnosis, cognitive scores, annual cognitive decline, activities of daily living (ADLs), neuropsychiatric symptoms (NPS), quality of life (QoL), and survival time for EO-AD and LO-AD patients.

RESULTS

Forty-two studies were included (EO-AD participants n = 5,544; LO-AD participants n = 16,042). An inverse variance method with random effects models was used to calculate overall effect estimates for each outcome. People with EO-AD had significantly poorer baseline cognitive performance and faster cognitive decline but longer survival times than people with LO-AD. There was no evidence that EO-AD patients differ from people with LO-AD in terms of symptom onset to diagnosis time, ADLs, and NPS. There were insufficient data to estimate overall effects of differences in QoL in EO-AD compared to LO-AD.

CONCLUSIONS

Our findings suggest that EO-AD differs from LO-AD in baseline cognition, cognitive decline, and survival time but otherwise has similar clinical characteristics to LO-AD. Larger studies using standardized questionnaires focusing on the clinical presentations are needed to better understand the impact of age of onset in AD.

The associations of socioeconomic status with incident dementia and Alzheimer's disease are modified by leucocyte telomere length: a population-based cohort study

Socio-economic status (SES) and biological aging are risk factors for dementia, including Alzheimer's disease, however, it is less clear if the associations with SES vary sufficiently across different biological age strata. We used data from 331,066 UK Biobank participants aged 38-73 with mean follow-up of 12 years to examine if associations between SES (assessed by educational attainment, employment status and household income) and dementia and Alzheimer's disease are modified by biological age (assessed by leucocyte telomere length: LTL). Diagnosis of events was ascertained through hospital admissions data. Cox regressions were used to estimate hazard ratios [HRs]. A consistent dose-response relationship was found, with participants in low SES and shorter LTL strata (double-exposed group) reporting 3.28 (95% confidence interval [CI] 2.57-4.20) and 3.44 (95% CI 2.35-5.04) times higher risks of incident dementia and Alzheimer's disease respectively, compared to those of high SES and longer LTL (least-exposed group). Of interest is a synergistic interaction between SES and LTL to increase risk of dementia (RERI 0.57, 95% CI 0.07-1.06) and Alzheimer's disease (RERI 0.79, 95% CI 0.02-1.56). Our findings that SES and biological age (LTL) are synergistic risk factors of dementia and Alzheimer's disease may suggest the need to target interventions among vulnerable sub-groups.

Study of the possible effect of sacubitril/valsartan combination versus valsartan on the cognitive function in Alzheimer's disease model in rats

Objectives: Alzheimer's disease (AD) is an irreversible, progressive neurodegenerative disorder. The proportion of elderly individuals at risk for AD and cardiovascular problems increases by raising life expectancy. The present study was designed to investigate the effect of the sacubitril/valsartan combination compared to that of valsartan alone in a rat model of AD. Methods: 72 male adult Wistar rats were divided into seven groups; control untreated rats received saline, control valsartan-treated rats received valsartan orally, control sacubitril/valsartan treated rats received sacubitril/valsartan orally, model rats received aluminum chloride i.p., model valsartan treated rats received aluminum chloride i.p. and valsartan orally and model sacubitril/valsartan treated rats received aluminum chloride i.p. and sacubitril/valsartan combination orally. All previous treatments continued on a daily basis for 6 weeks. At the second, fourth, and sixth weeks of the experiment, behavioral changes were evaluated using the Morris water maze and novel object recognition tests, and systolic blood pressure was measured. In the end, rat brain malondialdehyde and amyloid-beta 1-42 levels were measured, and the isolated hippocampus was evaluated histopathologically. Results: Valsartan improved AD symptoms in the aluminum-induced rat model, while the sacubitril/valsartan combination significantly worsened all tested parameters in both control and model rats compared with untreated and valsartan-treated animals. Conclusion: Based on the current study's findings, valsartan did not increase the risk for AD development in control rats and improved AD symptoms in a rat model, while sacubitril/valsartan combination increased the risk of AD in control rats and worsened the condition in a rat model.

Different rates of cognitive decline in autosomal dominant and late-onset Alzheimer disease

As prevention trials advance with autosomal dominant Alzheimer disease (ADAD) participants, understanding the similarities and differences between ADAD and "sporadic" late-onset AD (LOAD) is critical to determine generalizability of findings between these cohorts. Cognitive trajectories of ADAD mutation carriers (MCs) and autopsy-confirmed LOAD individuals were compared to address this question. Longitudinal rates of change on cognitive measures were compared in ADAD MCs (n = 310) and autopsy-confirmed LOAD participants (n = 163) before and after symptom onset (estimated/observed). LOAD participants declined more rapidly in the presymptomatic (preclinical) period and performed more poorly at symptom onset than ADAD participants on a cognitive composite. After symptom onset, however, the younger ADAD MCs declined more rapidly. The similar but not identical cognitive trajectories (declining but at different rates) for ADAD and LOAD suggest common AD pathologies but with some differences.

Earlier Alzheimer’s disease onset is associated with tau pathology in brain hub regions and facilitated tau spreading

In Alzheimer’s disease (AD), younger symptom onset is associated with accelerated disease progression and tau spreading, yet the mechanisms underlying faster disease manifestation are unknown. To address this, we combined resting-state fMRI and longitudinal tau-PET in two independent samples of controls and biomarker-confirmed AD patients (ADNI/BioFINDER, n = 240/57). Consistent across both samples, we found that younger symptomatic AD patients showed stronger tau-PET in globally connected fronto-parietal hubs, i.e., regions that are critical for maintaining cognition in AD. Stronger tau-PET in hubs predicted faster subsequent tau accumulation, suggesting that tau in globally connected regions facilitates connectivity-mediated tau spreading. Further, stronger tau-PET in hubs mediated the association between younger age and faster tau accumulation in symptomatic AD patients, which predicted faster cognitive decline. These independently validated findings suggest that younger AD symptom onset is associated with stronger tau pathology in brain hubs, and accelerated tau spreading throughout connected brain regions and cognitive decline.

Rural-Urban Disparities in Diagnosis of Early-Onset Dementia

IMPORTANCE

Limited access to appropriate specialists and testing may be associated with delayed diagnosis and symptom management for patients with early-onset Alzheimer disease and related dementias (ADRDs).

OBJECTIVES

To examine rural vs urban differences in diagnostic and symptom management service use among patients with early-onset ADRDs.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study was conducted using commercial claims from 2012 to 2017. Included patients were those with early-onset ADRDs aged 40 to 64 years, including new patients, defined as those with no claims of ADRDs for 36 months before the first ADRD diagnosis. The likelihood of receiving diagnostic and symptom management services was estimated, with adjustment for individual-level variables associated with health care use. Data were analyzed from February 2021 to March 2022.

EXPOSURES

Rural residence.

MAIN OUTCOMES AND MEASURES

Among patients with new, early-onset ADRDs, use of psychological assessment and neuropsychological testing performed at the initial diagnosis (index date) or 90 days or less after the index date and use of brain imaging during the 180 days before the index date were collected. Access to different clinicians on the index date or 90 days or less after the index date was also collected, including visits to primary care physicians and nurse practitioners (PCPs) and specialty visits to psychologists, neurologists, and psychiatrists.

RESULTS

Among 71 799 patients with early-onset ADRD (mean [SD] age, 56.34 [6.05] years; 39 231 women [54.64%]), 8430 individuals had new early-onset ADRDs (mean [SD] age, 55.94 [6.30] years; 16 512 women [56.65%]). There were no statistically significant differences between new patients with early-onset ADRDs in rural vs urban areas in the use of psychological assessments, imaging studies, or visits to neurologists or psychiatrists. However, new patients in rural areas were less likely to receive neuropsychological testing (odds ratio [OR], 0.83; 95% CI, 0.70-0.98) or visit a psychologist (OR, 0.72; 95% CI, 0.60-0.85) compared with patients in urban areas. However, new patients in rural areas with early-onset ADRDs were more likely to have only PCP visits for diagnosis and symptom management compared with those in urban areas (OR, 1.40; 95% CI, 1.19-1.66).

CONCLUSIONS AND RELEVANCE

This study found that new patients with early-onset ADRDs in rural areas were less likely to receive neuropsychological testing or visit psychologists but more likely to be diagnosed and treated exclusively by PCPs compared with those in urban areas. These findings suggest that efforts, such as clinician education or teleconsultative guidance to PCPs, may be needed to enhance access to specialist services in rural areas.

Dissecting the clinical heterogeneity of early-onset Alzheimer's disease

Early-onset Alzheimer's disease (EOAD) is a rare but particularly devastating form of AD. Though notable for its high degree of clinical heterogeneity, EOAD is defined by the same neuropathological hallmarks underlying the more common, late-onset form of AD. In this review, we describe the various clinical syndromes associated with EOAD, including the typical amnestic phenotype as well as atypical variants affecting visuospatial, language, executive, behavioral, and motor functions. We go on to highlight advances in fluid biomarker research and describe how molecular, structural, and functional neuroimaging can be used not only to improve EOAD diagnostic acumen but also enhance our understanding of fundamental pathobiological changes occurring years (and even decades) before the onset of symptoms. In addition, we discuss genetic variation underlying EOAD, including pathogenic variants responsible for the well-known mendelian forms of EOAD as well as variants that may increase risk for the much more common forms of EOAD that are either considered to be sporadic or lack a clear autosomal-dominant inheritance pattern. Intriguingly, specific pathogenic variants in PRNP and MAPT-genes which are more commonly associated with other neurodegenerative diseases-may provide unexpectedly important insights into the formation of AD tau pathology. Genetic analysis of the atypical clinical syndromes associated with EOAD will continue to be challenging given their rarity, but integration of fluid biomarker data, multimodal imaging, and various 'omics techniques and their application to the study of large, multicenter cohorts will enable future discoveries of fundamental mechanisms underlying the development of EOAD and its varied clinical presentations.

Characterization of Alzheimer’s Disease Subtypes Based on Magnetic Resonance Imaging and Perfusion Single-Photon Emission Computed Tomography

Background: Alzheimer’s disease (AD) is a biologically heterogenous disease. Previous studies have reported the existence of various AD subtypes, and the various clinical features of the subtypes. However, inconsistent results have been obtained. Objective: To clarify the clinical characteristics of the various AD subtypes, by classifying probable AD into subtypes based on magnetic resonance imaging (MRI) and single-photon emission computed tomography (SPECT) findings. Methods: A total of 245 patients with probable AD were classified into the typical AD (TAD) subtype, limbic-predominant (LP) subtype, hippocampal-sparing (HS) subtype, and minimal-change (MC) subtype, based on the presence of medial temporal lobe atrophy on MRI and posterior cerebral hypoperfusion on SPECT. Demographics, including age, sex, body mass index, disease duration, education years, comorbidities, frailty, leisure activity, and neuropsychological findings were compared between the AD subtypes. Results: he frequency of TAD, LP, HS, and MC subtypes was 49%, 20%, 18%, and 13%, respectively. Patients with the LP subtype were older and characterized by fewer major comorbidities, higher frailty, and slower progression of disease. Patients with the HS subtype were younger and characterized by shorter disease duration, lower frailty, and preserved memory, but had prominent constructional dysfunction. Patients of the MC subtype were characterized by shorter disease duration, lower education level, less leisure activity, less impaired memory and orientation, and slower progression. Conclusion: Patients with different AD subtypes differed in their demographic and clinical features. The characterization of patients’ AD subtypes may provide effective support for the diagnosis, treatment, and care of AD patients.

Gender Differences in Demographic and Pharmacological Factors in Patients Diagnosed with Late-Onset of Alzheimer’s Disease

Background: Whether gender differences exist in late-onset of Alzheimer’s disease (LOAD) treated with cholinesterase inhibitors (ChEIs) is not fully understood. This study investigated demographic and pharmacological characteristics in LOAD patients to determine gender differences in LOAD patients treated with ChEIs alone and ChEIs with other medications. Methods: This 5-year retrospective data analysis included 9290 LOAD AD patients with 2949 men patients and 6341 women. Potential predictors of demographic and pharmacological characteristics associated gender differences in patients treated with and without ChEIs therapy were determined using univariate analysis, while multivariable models adjusted for demographic and pharmacological variables. Results: In the adjusted analysis, men patients with LOAD that presented with a history of alcohol use (ETOH) (OR = 1.339, 95% CI, 1.072–1.672, p = 0.010), treated with second generation antipsychotics (SGAs) (OR = 1.271, 95% CI, 1.003–1.610, p = 0.047), citalopram (OR = 5.103, 95% CI, 3.423–7.607, p < 0.001), memantine (OR = 4.409, 95% CI, 3.704–5.249, p < 0.001), and buspirone (OR = 2.166, 95% CI, 1.437–3.264, p < 0.001) were more likely to receive ChEIs therapy, whereas older men were less likely to be treated with ChEIs therapy. Women who were African Americans (OR = 1.387, 95% CI, 1.168–1.647, p < 0.001), that received memantine (OR = 3.412, 95% CI, 3.034–3.837, p < 0.001), selective serotonin reuptake inhibitor (SSRIs) (OR = 1.143, 95% CI, 1.016–1.287, p = 0.026), and a history of ETOH (OR = 2.109, 95% CI, 1.724–2.580, p < 0.001) were more likely to receive ChEIs therapy, whereas older women were less likely to receive ChEIs therapy. Conclusion: In both men and women patients, those with increasing age were less likely to be treated with ChEI therapy, while patients treated with memantine were also likely to receive ChEI therapy. Our findings highlight the importance for clinicians to optimize ChEI in LOAD to improve treatment effectiveness and eliminate gender differences in ChEI therapy.

Breakdown of specific functional brain networks in clinical variants of Alzheimer's disease

Alzheimer's disease (AD) is characterized by different clinical entities. Although AD phenotypes share a common molecular substrate (i.e., amyloid beta and tau accumulation), several clinicopathological differences exist. Brain functional networks might provide a macro-scale scaffolding to explain this heterogeneity. In this review, we summarize the evidence linking different large-scale functional network abnormalities to distinct AD phenotypes. Specifically, executive deficits in early-onset AD link with the dysfunction of networks that support sustained attention and executive functions. Posterior cortical atrophy relates to the breakdown of visual and dorsal attentional circuits, while the primary progressive aphasia variant of AD may be associated with the dysfunction of the left-lateralized language network. Additionally, network abnormalities might provide in vivo signatures for distinguishing proteinopathies that mimic AD, such as TAR DNA binding protein 43 related pathologies. These network differences vis-a-vis clinical syndromes are more evident in the earliest stage of AD. Finally, we discuss how these findings might pave the way for new tailored interventions targeting the most vulnerable brain circuit at the optimal time window to maximize clinical benefits.

When real life conditions do not follow textbook diagnosis: A diagnostic challenge from a neuropsychiatric clinic

We present the case of a 61-year-old retired catholic priest, who was adopted at a very young age, with psychiatric history of anxiety and depression presenting for evaluation of at least 4 year memory loss and word finding difficulties. Over the preceding couple of years his cognitive functions had rapidly declined. As a result, he became dependent on his elderly parents for most of his instrumental activities of daily living including administration of medication, financial management, and driving. He continues to be independent in his personal care. His presentation offered diagnostic challenges due to the interplay of anxiety and cognitive disorders involving both memory and language domains. In addition, he resisted to repeat formal neuropsychological evaluation. At the bedside, his poor effort on testing was often blamed on his severe anxiety confounding the clinical picture. Lack of knowledge of his family history and his childhood development, and unclear premorbid functioning complicated the diagnostic formulation. A differential diagnosis ranging from possible functional cognitive disorder to neurodevelopmental disorder and neurodegenerative disorders will be discussed.

Identification of Heterogeneous Subtypes of Mild Cognitive Impairment Using Cluster Analyses Based on PET Imaging of Tau and Astrogliosis

Background: Mild cognitive impairment (MCI) is a condition with diverse causes and clinical outcomes that can be categorized into subtypes. [¹⁸F]THK5351 has been known to detect reactive astrogliosis as well as tau which is accompanied by neurodegenerative changes. Here, we identified heterogeneous groups of MCI patients using THK retention patterns and a graph theory approach, allowing for the comparison of risk of progression to dementia in these MCI subgroups.

Methods: Ninety-seven participants including 60 MCI patients and individuals with normal cognition (NC, n = 37) were included and undertook 3T MRI, [¹⁸F]THK5351 PET, and detailed neuropsychological tests. [¹⁸F]Flutemetamol PET was also performed in 62 participants. We calculated similarities between MCI patients using their regional standardized uptake value ratio of THK retention in 75 ROIs, and clustered subjects with similar retention patterns using the Louvain method based on the modularity of the graph. The clusters of patients identified were compared with an age-matched control group using a general linear model. Dementia conversion was evaluated after a median follow-up duration of 34.6 months.

Results: MCI patients were categorized into four groups according to their THK retention patterns: (1) limbic type; (2) diffuse type; (3) sparse type; and (4) AD type (retention pattern as in AD). Subjects of the limbic type were characterized by older age, small hippocampal volumes, and reduced verbal memory and frontal/executive functions. Patients of the diffuse type had relatively large vascular burden, reduced memory capacity and some frontal/executive functions. Co-morbidity and mortality were more frequent in this subgroup. Subjects of the sparse type were younger and declined only in terms of visual memory and attention. No individuals in this subgroup converted to dementia. Patients in the AD type group exhibited the poorest cognitive function. They also had the smallest hippocampal volumes and the highest risk of progression to dementia (90.9%).

Conclusion: Using cluster analyses with [¹⁸F]THK5351 retention patterns, it is possible to identify clinically-distinct subgroups of MCI patients and those at greater risk of progression to dementia.

Predictors of Disease Progression in Early-Onset Alzheimer's Dementia: A Retrospective Cohort Study

OBJECTIVES

Early-onset Alzheimer's disease (EOAD), defined as onset of AD before the age of 65 years, is less common than the late-onset type, and little is known about the factors affecting disease progression. The aim of the study was to investigate factors influencing disease progression in people with EOAD.

DESIGN

Retrospective cohort study.

SETTING AND PARTICIPANTS

People with EOAD who were assessed and attended the specialist memory service at a university teaching hospital in a European setting, between 2000 and 2010.

MEASURES

Sociodemographic details and clinical and cognitive assessments at initial assessment were used as potential predictors of change in clinical status and outcome at final follow-up within the memory service.

RESULTS

Of the 101 people diagnosed with EOAD during this period, 96 patients were followed up (53 women; aged 59 ± 4.9 years; mean follow-up 36.3 ± 29.12 months). Patients were classified as Stable (n = 25) if continued within the memory service or discharged to primary care, and those transferred to other specialist services (n = 66) for further inputs, institutional care (n = 4), or died (n = 1) were classified as Worseners (n = 71). Lower education (P = .008), lower Cambridge Cognition Examination scores (P = .049), and presence of family history of dementia [P = .012, χ² (1) = 8.84] was associated with worse change in clinical status. Furthermore, cognitive deficits such as lower scores on comprehension, recent memory, and executive functions were found to predict a worse clinical outcome.

CONCLUSIONS AND IMPLICATIONS

Identification of predictors of faster disease progression has significant clinical benefit, allowing clinicians to estimate prognosis and plan patient care accordingly.

Late-onset vs nonmendelian early-onset Alzheimer disease: A distinction without a difference?

There is mounting evidence that only a small fraction of early-onset Alzheimer disease cases (onset <65 years) are explained by known mutations. Even multiplex families with early onset often also have late-onset cases, suggesting that the commonly applied categorization of Alzheimer disease into early- and late-onset forms may not reflect distinct underlying etiology. Nevertheless, this categorization continues to govern today's research and the design of clinical trials. The aim of this review is to evaluate this categorization by providing a comprehensive, critical review of reported clinical, neuropathologic, and genomic characteristics of both onset-based subtypes and explore potential overlap between both categories. The article will lay out the need to comprehensively assess the phenotypic, neuropathologic, and molecular variability in Alzheimer disease and identify factors explaining the observed significant variation in onset age in persons with and without known mutations. The article will critically review ongoing large-scale genomic efforts in Alzheimer disease research (e.g., Alzheimer Disease Sequencing Project, Dominantly Inherited Alzheimer Network, Alzheimer Disease Neuroimaging Initiative) and their shortcomings to disentangle the delineation of unexplained nonmendelian early-onset from late-onset and mendelian forms of Alzheimer disease. In addition, it will outline specific approaches including epigenetic research through which a comprehensive characterization of this delineation can be achieved.

Disentangling Heterogeneity in Alzheimer's Disease and Related Dementias Using Data-Driven Methods

Brain aging is a complex process that includes atrophy, vascular injury, and a variety of age-associated neurodegenerative pathologies, together determining an individual's course of cognitive decline. While Alzheimer's disease and related dementias contribute to the heterogeneity of brain aging, these conditions themselves are also heterogeneous in their clinical presentation, progression, and pattern of neural injury. We reviewed studies that leveraged data-driven approaches to examining heterogeneity in Alzheimer's disease and related dementias, with a principal focus on neuroimaging studies exploring subtypes of regional neurodegeneration patterns. Over the past decade, the steadily increasing wealth of clinical, neuroimaging, and molecular biomarker information collected within large-scale observational cohort studies has allowed for a richer understanding of the variability of disease expression within the aging and Alzheimer's disease and related dementias continuum. Moreover, the availability of these large-scale datasets has supported the development and increasing application of clustering techniques for studying disease heterogeneity in a data-driven manner. In particular, data-driven studies have led to new discoveries of previously unappreciated disease subtypes characterized by distinct neuroimaging patterns of regional neurodegeneration, which are paralleled by heterogeneous profiles of pathological, clinical, and molecular biomarker characteristics. Incorporating these findings into novel frameworks for more differentiated disease stratification holds great promise for improving individualized diagnosis and prognosis of expected clinical progression, and provides opportunities for development of precision medicine approaches for therapeutic intervention. We conclude with an account of the principal challenges associated with data-driven heterogeneity analyses and outline avenues for future developments in the field.

The combined effects of microglia activation and brain glucose hypometabolism in early-onset Alzheimer's disease

Background

Early-onset Alzheimer’s disease (EOAD) is characterized by young age of onset (< 65 years), severe neurodegeneration, and rapid disease progression, thus differing significantly from typical late-onset Alzheimer’s disease. Growing evidence suggests a primary role of neuroinflammation in AD pathogenesis. However, the role of microglia activation in EOAD remains a poorly explored field. Investigating microglial activation and its influence on the development of synaptic dysfunction and neuronal loss in EOAD may contribute to the understanding of its pathophysiology and to subject selection in clinical trials. In our study, we aimed to assess the amount of neuroinflammation and neurodegeneration and their relationship in EOAD patients, through positron emission tomography (PET) measures of microglia activation and brain metabolic changes.

Methods

We prospectively enrolled 12 EOAD patients, classified according to standard criteria, who underwent standard neurological and neuropsychological evaluation, CSF analysis, brain MRI, and both [¹⁸F]-FDG PET and [¹¹C]-(R)-PK11195 PET. Healthy controls databases were used for statistical comparison. [¹⁸F]-FDG PET brain metabolism in single subjects and as a group was assessed by an optimized SPM voxel-wise single-subject method. [¹¹C]-PK11195 PET binding potentials were obtained using reference regions selected with an optimized clustering procedure followed by a parametric analysis. We performed a topographic interaction analysis and correlation analysis in AD-signature metabolic dysfunctional regions and regions of microglia activation. A network connectivity analysis was performed using the interaction regions of hypometabolism and [¹¹C]-PK11195 PET BP increases.

Results

EOAD patients showed a significant and extended microglia activation, as [¹¹C]-PK11195 PET binding potential increases, and hypometabolism in typical AD-signature brain regions, i.e., temporo-parietal cortex, with additional variable frontal and occipital hypometabolism in the EOAD variants. There was a spatial concordance in the interaction areas and significant correlations between the two biological changes. The network analysis showed a disruption of frontal connectivity induced by the metabolic/microglia effects.

Conclusion

The severe microglia activation characterizing EOAD and contributing to neurodegeneration may be a marker of rapid disease progression. The coupling between brain glucose hypometabolism and local immune response in AD-signature regions supports their biological interaction.

The A4 study: β-amyloid and cognition in 4432 cognitively unimpaired adults

Objective

To clarify the preclinical stage of Alzheimer’s disease by estimating when β‐amyloid accumulation first becomes associated with changes in cognition.

Methods

Here we studied a large group (N = 4432) of cognitively unimpaired individuals who were screened for inclusion in the A4 trial (age 65–85) to assess the effect of subthreshold levels of β‐amyloid on cognition and to identify which cognitive domains first become affected.

Results

β‐amyloid accumulation was linked to significant cognitive dysfunction in cognitively unimpaired participants with subthreshold levels of β‐amyloid in multiple measures of memory (Logical Memory Delayed Recall, P = 0.03; Free and Cued Selective Reminding Test, P < 0.001), the Preclinical Alzheimer’s Cognitive Composite (P = 0.01), and was marginally associated with decreased executive function (Digit Symbol Substitution, P = 0.07). Significantly, decreased cognitive scores were associated with suprathreshold levels of β‐amyloid, across all measures (P < 0.05). The Free and Cued Selective Reminding Test, a list recall memory test, appeared most sensitive to β‐amyloid ‐related decreases in average cognitive scores, outperforming all other cognitive domains, including the narrative recall memory test, Logical Memory.

Interpretation

Clinical trials for cognitively unimpaired β‐amyloid‐positive individuals will include a large number of individuals where mechanisms downstream from β‐amyloid pathology are already activated. These findings have implications for primary and secondary prevention of Alzheimer’s disease.

Report of a Case of Creutzfeldt-Jakob Disease With an Unusual Clinical Presentation

We describe the clinical features, neuropsychological tests, laboratory, electroencephalography (EEG), magnetic resonance imaging (MRI) and positron emission tomography (PET) findings of a 59-year-old woman who presented to our Centre for cognitive impairment since few months, with language disturbances, particularly anomia, dyscalculia, and memory loss. The clinical and neuropsychological features were non-specific and overlapping with those of other rapidly progressing neurodegenerative disorders. However, brain MRI played a pivotal role in the diagnosis, showing cortical diffusion restriction, particularly in the parietal lobes and posterior cingulum, with sparing of the perirolandic cortex, typical of Creutzfeldt-Jakob disease (CJD). Brain MRI abnormalities were visible since the first evaluation and remained stable at 2 and 6 weeks follow up. Basal ganglia and thalami were never involved. PET showed left lateralized reduced glucose metabolism, with partial overlap with MRI signal abnormalities. Despite MRI were strongly indicative of CJD, clinical, laboratory and EEG findings did not fulfill the diagnostic criteria for CJD which applied at the time of clinical assessment. Indeed, neither myoclonus, visual or cerebellar signs or akinetic mutism were present. Also, the characteristic periodic sharp wave complexes were absent at baseline EEG, and the CSF assay for 14–3–3 was negative. We, therefore, performed a real-time quaking-induced conversion (RT-QuIC) assay on a frozen sample of corticospinal fluid (CSF), which showed a positive result. RT-QuIC is a prion protein conversion assay that has shown high diagnostic sensitivity and specificity for the diagnosis of CJD. RT-QuIC has been recently incorporated in the National CJD Research and Surveillance Unit and Center for Disease Control and Prevention (CDC) diagnostic criteria for CJD. The fatal evolution of the disease brought the patient to death 13 months after symptoms onset. Pathology proved the diagnosis of sporadic CJD, subtype MM/MV 2C.

Early-onset Alzheimer Disease and Its Variants

PURPOSE OF REVIEW

Early-onset Alzheimer disease (AD) is defined as having an age of onset younger than 65 years. While early-onset AD is often overshadowed by the more common late-onset AD, recognition of the differences between early- and late-onset AD is important for clinicians.

RECENT FINDINGS

Early-onset AD comprises about 5% to 6% of cases of AD and includes a substantial percentage of phenotypic variants that differ from the usual amnestic presentation of typical AD. Characteristics of early-onset AD in comparison to late-onset AD include a larger genetic predisposition (familial mutations and summed polygenic risk), more aggressive course, more frequent delay in diagnosis, higher prevalence of traumatic brain injury, less memory impairment and greater involvement of other cognitive domains on presentation, and greater psychosocial difficulties. Neuroimaging features of early-onset AD in comparison to late-onset AD include greater frequency of hippocampal sparing and posterior neocortical atrophy, increased tau burden, and greater connectomic changes affecting frontoparietal networks rather than the default mode network.

SUMMARY

Early-onset AD differs substantially from late-onset AD, with different phenotypic presentations, greater genetic predisposition, and differences in neuropathologic burden and topography. Early-onset AD more often presents with nonamnestic phenotypic variants that spare the hippocampi and with greater tau burden in posterior neocortices. The early-onset AD phenotypic variants involve different neural networks than typical AD. The management of early-onset AD is similar to that of late-onset AD but with special emphasis on targeting specific cognitive areas and more age-appropriate psychosocial support and education.

Survival and life-expectancy in a young-onset dementia cohort with six years of follow-up: the NeedYD-study

OBJECTIVES

The aim of this study was to investigate survival time and life-expectancy in people with young-onset dementia (YOD) and to examine the relationship with age, sex, dementia subtype and comorbidity.

DESIGN, SETTING AND PARTICIPANTS

Survival was examined in 198 participants in the Needs in Young-onset Dementia study, including participants with Alzheimer's dementia (AD), vascular dementia (VaD) and frontotemporal dementia (FTD).

MEASURES

The primary outcomes were survival time after symptom onset and after date of diagnosis. Cox proportional hazards models were used to explore the relationship between survival and age, sex, dementia subtype and comorbidity. Additionally, the impact on remaining life expectancy was explored.

RESULTS

During the six-year follow-up, 77 of the participants died (38.9%), 78 participants survived (39.4%) and 43 were lost to follow-up (21.7%). The mean survival time after symptom onset and diagnosis was 209 months (95% CI 185-233) and 120 months (95% CI 110-130) respectively. Participants with AD had a statistically significant shorter survival compared with VaD participants, both regarding survival after symptom onset (p = 0.047) as well as regarding survival after diagnosis (p = 0.049). Younger age at symptom onset or at diagnosis was associated with longer survival times. The remaining life expectancy, after diagnosis, was reduced with 51% for males and 59% for females compared to the life expectancy of the general population in the same age groups.

CONCLUSION/IMPLICATIONS

It is important to consider the dementia subtype when persons with YOD and their families are informed about the prognosis of survival. Our study suggests longer survival times compared to other studies on YOD, and survival is prolonged compared to studies on LOD. Younger age at symptom onset or at diagnosis was positively related to survival but diagnosis at younger ages, nevertheless, still diminishes life expectancy dramatically.

Young-onset Alzheimer dementia: a comparison of Brazilian and Norwegian carers' experiences and needs for assistance

OBJECTIVES

Although dementia typically occurs in older people, it can also emerge in people aged younger than 65 years in the form of young-onset dementia, the most common type of which is Alzheimer's disease (AD). However, few studies have examined the needs of persons with young-onset AD (YO-AD) and their families, and cross-cultural research on the topic is even scarcer. In response, we investigated the situations, experiences and needs for assistance of carers of persons with YO-AD in Brazil and Norway.

METHODS

As part of our qualitative study, we formed a convenience sample of Brazilian (n = 9; 7 women) and Norwegian carers (n = 11; 6 women) in 2014 and 2015, respectively, and analysed data in light of a modified version of grounded theory.

RESULTS

Carers' narratives from both countries revealed five common themes in terms of how YO-AD affected carers' psychological and emotional well-being, physical well-being, professional and financial well-being, social lives and need for support services.

CONCLUSIONS

The infrequent differences between carers of persons with YO-AD in Brazil and Norway indicate that carers' problems are highly similar regardless of cultural differences and public services provided. Copyright © 2017 John Wiley & Sons, Ltd.

Early- versus late-onset Alzheimer's disease in clinical practice: cognitive and global outcomes over 3 years

BACKGROUND

Whether age at onset influences Alzheimer's disease (AD) progression and the effectiveness of cholinesterase inhibitor (ChEI) therapy is not clear. We aimed to compare longitudinal cognitive and global outcomes in ChEI-treated patients with early-onset Alzheimer's disease (EOAD) versus late-onset Alzheimer's disease (LOAD) in clinical practice.

METHODS

This 3-year, prospective, observational, multicentre study included 1017 participants with mild to moderate AD; 143 had EOAD (age at onset < 65 years) and 874 had LOAD (age at onset ≥ 65 years). At baseline and semi-annually, patients were assessed using cognitive, global and activities of daily living (ADL) scales, and the dose of ChEI was recorded. Potential predictors of decline were analysed using mixed-effects models.

RESULTS

Six-month response to ChEI therapy and long-term prognosis in cognitive and global performance were similar between the age-at-onset groups. However, deterioration was significantly faster when using the Alzheimer's Disease Assessment Scale-Cognitive subscale (ADAS-Cog) over 3 years in participants with EOAD than in those with LOAD; hence, prediction models for the mean ADAS-Cog trajectories are presented. The younger cohort had a larger proportion of homozygote apolipoprotein E (APOE) ε4 allele carriers than the older cohort; however, APOE genotype was not a significant predictor of cognitive impairment in the multivariate models. A slower rate of cognitive progression was related to initiation of ChEIs at an earlier stage of AD, higher ChEI dose and fewer years of education in both groups. In LOAD, male sex, better instrumental ADL ability and no antipsychotic drug use were additional protective characteristics. The older patients received a lower ChEI dose than the younger individuals during most of the study period.

CONCLUSIONS

Although the participants with EOAD showed a faster decline in ADAS-Cog, had a longer duration of AD before diagnosis, and had a higher frequency of two APOE ε4 alleles than those with LOAD, the cognitive and global responses to ChEI treatment and the longitudinal outcomes after 3 years were similar between the age-at-onset groups. A higher mean dose of ChEI and better cognitive status at the start of therapy were independent protective factors in both groups, stressing the importance of early treatment in adequate doses for all patients with AD.

Is Entresto good for the brain?

The main stay pharmacotherapy for heart failure (HF) is targeted towards rennin-angiotensin-aldosterone (RAAS) and neprilysin pathways (NP). Both therapeutic strategies decreases morbidity and mortality but also carry considerable adverse effects. This review of the literature highlights the new generation of HF drug, sacubitril-valsartan (SV), trade name Entresto (researched as LCZ696, Novartis) which simultaneously blocks RAAS and NP. This dual action of angiotensin receptors blocker and neprilysin inhibitor (NPi) has improved HF prognosis and it is an evolution in the management of HF. Although the initial follow-up of patients treated with SV has yielded promising results, there are concerns regarding potential side effects especially an increase in the risk of Alzheimer’s disease (AD) and young onset of AD. NPi interferes with the breakdown and clearing of beta-amyloid peptides, the plaques seen in AD, raising concern for AD in SV patients. On the other hand, hypertension and cardiovascular diseases are established risk factors for AD which can be decreased by SV therapy. It is therefore essential that SV treated patients are followed up over an extended period of time to detect any adverse cognitive changes.

Early-versus Late-Onset Alzheimer Disease: Long-Term Functional Outcomes, Nursing Home Placement, and Risk Factors for Rate of Progression

BACKGROUND/AIMS

Whether age at onset influences functional deterioration in Alzheimer disease (AD) is unclear. We, therefore, investigated risk factors for progression in activities of daily living (ADL) and nursing home placement (NHP) in cholinesterase inhibitor (ChEI)-treated patients with early-onset AD (EOAD) versus late-onset AD (LOAD).

METHODS

This 3-year, prospective, observational, multicenter study included 1,017 participants with mild-to-moderate AD; 143 had EOAD (onset <65 years) and 874 LOAD (onset ≥65 years). Possible sociodemographic and clinical factors that could affect functional outcome and NHP were analyzed using mixed-effects models and logistic regression, respectively.

RESULTS

Younger individuals exhibited longer illness duration before AD diagnosis, whereas 6-month functional response to ChEI therapy, 3-year changes in ADL capacities, time from diagnosis to NHP, and survival time in nursing homes were similar between the groups. In LOAD, a higher ChEI dose, no antidepressant use, and lower education level were protective factors for slower instrumental ADL (IADL) decline. In EOAD, antihypertensives/cardiac therapy implied faster IADL progression but lower risk of NHP.

CONCLUSION

This study highlights the clinical importance of an earlier diagnosis and treatment initiation and the need for functional evaluations in EOAD. Despite the age differences between EOAD and LOAD, a similar need for nursing homes was observed.

Early-Onset Alzheimer Disease

Early-onset Alzheimer disease (EOAD), with onset in individuals younger than 65 years, although overshadowed by the more common late-onset AD (LOAD), differs significantly from LOAD. EOAD comprises approximately 5% of AD and is associated with delays in diagnosis, aggressive course, and age-related psychosocial needs. One source of confusion is that a substantial percentage of EOAD are phenotypic variants that differ from the usual memory-disordered presentation of typical AD. The management of EOAD is similar to that for LOAD, but special emphasis should be placed on targeting the specific cognitive areas involved and more age-appropriate psychosocial support and education.

Functional Status Predicts Awareness in Late-Onset but not in Early-Onset Alzheimer Disease

This study aims to assess whether there are differences between the level of awareness in early-onset Alzheimer disease (EOAD) and late-onset Alzheimer disease (LOAD) and to test its association with quality of life (QOL). A consecutive series of 207 people with Alzheimer disease and their caregivers were selected from an outpatient unit. There were no significant differences in awareness. In LOAD, impairment on awareness was predicted by functional level (β = .37, P < .001), self ( P = .006), and informant report of QOL ( P = .010). The predictors of unawareness in EOAD were self ( P = .002) and informant report of QOL ( P < .001). There is a specific profile of functional deficits underlying awareness in people with LOAD. Additionally, reports of EOAD QOL were more strongly related to awareness than in people with LOAD.

Differences in Alzheimer disease clinical trial outcomes based on age of the participants

OBJECTIVE

We tested the a priori hypothesis that older participants differ in rates of decline on cognitive outcomes compared with younger participants, and examined the potential effect of age distributions on individual clinical trial outcomes.

METHODS

From a meta-database of 18 studies from the Alzheimer's Disease Cooperative Study and the Alzheimer's Disease Neuroimaging Initiative, we included a cohort of 2,793 participants for whom there were baseline demographic data and at least one postbaseline cognitive assessment on the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog), Clinical Dementia Rating-Sum of Boxes (CDR-SB), or Mini-Mental State Examination (MMSE). We used mixed-effects models (random coefficient models) to estimate change on the outcomes across 7 age groups ranging from younger than 61 years to older than 85 years after adjusting for education.

RESULTS

Significant worsening occurred in all age groups on all outcomes over time. The 4 older groups, aged 71 years and older, showed slower rates of decline on the ADAS-cog than the younger groups (p = 0.001). The older groups scored 2-3, 2-5, and 4-6 points better than the younger groups at 12, 18, and 24 months, respectively. There were similar differences across age groups for the MMSE, but not for the CDR-SB.

CONCLUSIONS

The differences in change on the ADAS-cog between older and younger participants are substantially greater than differences expected between experimental drugs and placebo in current trials or differences between marketed cholinesterase inhibitors and placebo. The clinical interpretation of change on the ADAS-cog or MMSE differs depending on age. Until predictors of decline are better understood, considering effects of age on rates of change is particularly important regarding clinical practice and outcomes of trials.