Non-drug Therapies for Alzheimer's Disease: A Review

Alzheimer's disease: a comprehensive review of epidemiology, risk factors, symptoms diagnosis, management, caregiving, advanced treatments and associated challenges

Background

Alzheimer's disease (AD) is a chronic, progressive neurodegenerative disorder characterized by cognitive decline, memory loss, and impaired reasoning. It is the leading cause of dementia in older adults, marked by the pathological accumulation of amyloid-beta plaques and neurofibrillary tangles. These pathological changes lead to widespread neuronal damage, significantly impacting daily functioning and quality of life.

Objective

This comprehensive review aims to explore various aspects of Alzheimer's disease, including its epidemiology, risk factors, clinical presentation, diagnostic advancements, management strategies, caregiving challenges, and emerging therapeutic interventions.

Methods

A systematic literature review was conducted across multiple electronic databases, including PubMed, MEDLINE, Cochrane Library, and Scopus, from their inception to May 2024. The search strategy incorporated a combination of keywords and Medical Subject Headings (MeSH) terms such as "Alzheimer's disease," "epidemiology," "risk factors," "symptoms," "diagnosis," "management," "caregiving," "treatment," and "novel therapies." Boolean operators (AND, OR) were used to refine the search, ensuring a comprehensive analysis of the existing literature on Alzheimer's disease.

Results

AD is significantly influenced by genetic predispositions, such as the apolipoprotein E (APOE) ε4 allele, along with modifiable environmental factors like diet, physical activity, and cognitive engagement. Diagnostic approaches have evolved with advances in neuroimaging techniques (MRI, PET), and biomarker analysis, allowing for earlier detection and intervention. The National Institute on Aging and the Alzheimer's Association have updated diagnostic criteria to include biomarker data, enhancing early diagnosis.

Conclusion

The management of AD includes pharmacological treatments, such as cholinesterase inhibitors and NMDA receptor antagonists, which provide symptomatic relief but do not slow disease progression. Emerging therapies, including amyloid-beta and tau-targeting treatments, gene therapy, and immunotherapy, offer potential for disease modification. The critical role of caregivers is underscored, as they face considerable emotional, physical, and financial burdens. Support programs, communication strategies, and educational interventions are essential for improving caregiving outcomes. While significant advancements have been made in understanding and managing AD, ongoing research is necessary to identify new therapeutic targets and enhance diagnostic and treatment strategies. A holistic approach, integrating clinical, genetic, and environmental factors, is essential for addressing the multifaceted challenges of Alzheimer's disease and improving outcomes for both patients and caregivers.

Alzheimer's Disease, Obesity, and Type 2 Diabetes: Focus on Common Neuroglial Dysfunctions (Critical Review and New Data on Human Brain and Models)

BACKGROUND/OBJECTIVES

Obesity, type 2 diabetes (T2D), and Alzheimer's disease (AD) are pathologies that affect millions of people worldwide. They have no effective therapy and are difficult to prevent and control when they develop. It has been known for many years that these diseases have many pathogenic aspects in common. We highlight in this review that neuroglial cells (astroglia, oligodendroglia, and microglia) play a vital role in the origin, clinical-pathological development, and course of brain neurodegeneration. Moreover, we include the new results of a T2D-AD mouse model (APP+PS1 mice on a high-calorie diet) that we are investigating.

METHODS

Critical bibliographic revision and biochemical neuropathological study of neuroglia in a T2D-AD model.

RESULTS

T2D and AD are not only "connected" by producing complex pathologies in the same individual (obesity, T2D, and AD), but they also have many common pathogenic mechanisms. These include insulin resistance, hyperinsulinemia, hyperglycemia, oxidative stress, mitochondrial dysfunction, and inflammation (both peripheral and central-or neuroinflammation). Cognitive impairment and AD are the maximum exponents of brain neurodegeneration in these pathological processes. both due to the dysfunctions induced by metabolic changes in peripheral tissues and inadequate neurotoxic responses to changes in the brain. In this review, we first analyze the common pathogenic mechanisms of obesity, T2D, and AD (and/or cerebral vascular dementia) that induce transcendental changes and responses in neuroglia. The relationships between T2D and AD discussed mainly focus on neuroglial responses. Next, we present neuroglial changes within their neuropathological context in diverse scenarios: (a) aging involution and neurodegenerative disorders, (b) human obesity and diabetes and obesity/diabetes models, (c) human AD and in AD models, and (d) human AD-T2D and AD-T2D models. An important part of the data presented comes from our own studies on humans and experimental models over the past few years. In the T2D-AD section, we included the results of a T2D-AD mouse model (APP+PS1 mice on a high-calorie diet) that we investigated, which showed that neuroglial dysfunctions (astrocytosis and microgliosis) manifest before the appearance of amyloid neuropathology, and that the amyloid pathology is greater than that presented by mice fed a normal, non-high-caloric diet A broad review is finally included on pharmacological, cellular, genic, and non-pharmacological (especially diet and lifestyle) neuroglial-related treatments, as well as clinical trials in a comparative way between T2D and AD. These neuroglial treatments need to be included in the multimodal/integral treatments of T2D and AD to achieve greater therapeutic efficacy in many millions of patients.

CONCLUSIONS

Neuroglial alterations (especially in astroglia and microglia, cornerstones of neuroinflammation) are markedly defining brain neurodegeneration in T2D and A, although there are some not significant differences between each of the studied pathologies. Neuroglial therapies are a very important and p. promising tool that are being developed to prevent and/or treat brain dysfunction in T2D-AD. The need for further research in two very different directions is evident: (a) characterization of the phenotypic changes of astrocytes and microglial cells in each region of the brain and in each phase of development of each isolated and associated pathology (single-cell studies are mandatory) to better understand the pathologies and define new therapeutic targets; (b) studying new therapeutic avenues to normalize the function of neuroglial cells (preventing neurotoxic responses and/or reversing them) in these pathologies, as well as the phenotypic characteristics in each moment of the course and place of the neurodegenerative process.

The 40-Hz White Light Emitting Diode to Alleviate Psychiatric Symptoms Induced by Streptozotocin In Vivo

Introduction

A 40-Hz white light emitting diode (WLED) has emerged as an alternative nonpharmacological and noninvasive approach to Alzheimer disease (AD). Here, we investigated the therapeutic effects of 40-Hz WLED on psychiatric symptoms (PS) and the contribution of mitochondrial factors in the early stages of sporadic AD (sAD) in rats.

Methods

In male Wistar rats, the AD model was induced via intracerebroventricular (ICV) injection of streptozotocin (STZ). After recovering (7 days) from stereotaxic surgery, 40-Hz WLED exposure was performed for 7 consecutive days lasting 15 min/d. Behavioral (elevated plus maze (EPM), force swim test, and social interaction test), enzymatic, and molecular assays were conducted 24 hours after the last 40-Hz WLED exposure.

Results

Behavioral tasks revealed that 40-Hz WLED exposure in STZ-induced toxicity rats lowered anxiety and depression and increased social interaction. Furthermore, the 40-Hz WLED therapy in STZ-induced toxicity rats increased catalase (CAT) activity in the amygdala, decreased the activity of monoamine oxidases A and B in the whole brain, and increased mitochondrial DNA in the hippocampus.

Conclusion

The current study supports that 40-Hz WLED therapy improved PS and biomarkers in the early stages of sAD. Also, a potential relationship between PS and alterations in mitochondrial markers in certain brain regions seems to exist.

Current trends in psychotherapies and psychosocial interventions for people with dementia: a scoping review of randomized controlled trials

An outcome of dementia is a progressive decline in cognitive function. Implementing psychotherapies and psychosocial interventions is crucial for bolstering cognitive abilities, promoting independence, and elevating the quality of life for individuals with dementia. This review aims to identify current trends in psychotherapies and psychosocial interventions for people with dementia. A Scoping review was developed based on the framework proposed by Arksey and O'Malley. The literature search was conducted on electronic databases, including Scopus, Cochrane Central Register of Controlled Trials, MEDLINE, CINAHL, Nursing & Allied Health Collection, and MedicLatina. Executed in June 2023, the search focused on articles published in English, Portuguese, and Spanish between 2013 and 2023. Through this search, 1409 articles were initially identified. After selecting and analyzing the reports, sixteen trials were included in this review. Eight distinct categories were identified, covering different strategies. These categories run from computerized game-based cognitive training and reminiscence therapy to compensatory and restorative strategies, memory and attention training, calculation training, dual-task training, counseling, and personalized goal attainment. The findings of this scoping review highlight the diverse landscape of psychotherapies and psychosocial interventions for people with dementia.

SIRT2 as a potential new therapeutic target for Alzheimer's disease

Alzheimer's disease is the most common cause of dementia globally with an increasing incidence over the years, bringing a heavy burden to individuals and society due to the lack of an effective treatment. In this context, sirtuin 2, the sirtuin with the highest expression in the brain, has emerged as a potential therapeutic target for neurodegenerative diseases. This review summarizes and discusses the complex roles of sirtuin 2 in different molecular mechanisms involved in Alzheimer's disease such as amyloid and tau pathology, microtubule stability, neuroinflammation, myelin formation, autophagy, and oxidative stress. The role of sirtuin 2 in all these processes highlights its potential implication in the etiology and development of Alzheimer's disease. However, its presence in different cell types and its enormous variety of substrates leads to apparently contradictory conclusions when it comes to understanding its specific functions. Further studies in sirtuin 2 research with selective sirtuin 2 modulators targeting specific sirtuin 2 substrates are necessary to clarify its specific functions under different conditions and to validate it as a novel pharmacological target. This will contribute to the development of new treatment strategies, not only for Alzheimer's disease but also for other neurodegenerative diseases.

Non-Pharmacological Exercise Randomized Controlled Trials in Alzheimer's Disease

This narrative review aimed to summarize evidence on responses to exercise in pre-clinical Alzheimer's disease (AD) and on how long-term exercise programs work to improve neuropsychiatric symptoms and cognitive performance. We conducted a narrative review of the body of research on the benefits of long-term exercise programs in improving cognitive performance and reducing neuropsychiatric scores in patients with AD. Long-term exercise therapy appears to improve blood flow, increase hippocampal volume, and promote neurogenesis in patients with AD. Higher levels of physical activity are associated with a lower chance of developing the disease, and most prospective studies have shown that physical inactivity is one of the most prevalent modifiable risk factors for the development of AD. Exercise appears to be beneficial in improving cognitive function, a neuropsychiatric symptom of AD. Exercise has been shown to have fewer side effects, such as non-pharmacological effects and better adherence than medication. In this review, experts provided a snapshot and authoritative summary of evidence for non-pharmacological exercise in patients with AD based on the best synthesis efforts, identified the main knowledge gaps and relevant barriers, and provided directions for future research. Furthermore, experts in randomized trial designs provided practical details and recommendations for researchers working in this area, underscoring the importance of relevant topics.

Neuroprotective Effect of Curcumin-Loaded RGD Peptide-PEGylated Nanoliposomes

Curcumin is known for its anti-inflammatory, neuroprotective, and antioxidant properties, but its use in biological applications is hindered by its sensitivity to light, oxygen, and temperature. Furthermore, due to its low water solubility, curcumin has a poor pharmacokinetic profile and bioavailability. In this study, we evaluated the potential application of curcumin as a neuroprotective agent encapsulated in RGD peptide-PEGylated nanoliposomes developed from salmon-derived lecithin. Salmon lecithin, rich in polyunsaturated fatty acids, was used to formulate empty or curcumin-loaded nanoliposomes. Transmission electron microscopy, dynamic light scattering, and nanoparticle tracking analysis characterizations indicated that the marine-derived peptide-PEGylated nanoliposomes were spherical in shape, nanometric in size, and with an overall negative charge. Cytotoxicity tests of curcumin-loaded nanoliposomes revealed an improved tolerance of neurons to curcumin as compared to free curcumin. Wild-type SH-SY5Y were treated for 24 h with curcumin-loaded nanoliposomes, followed by 24 h incubation with conditioned media of SH-SY5Y expressing the Swedish mutation of APP containing a high ratio of Aβ40/42 peptides. Our results revealed significantly lower Aβ-induced cell toxicity in cells pre-treated with RGD peptide-PEGylated curcumin-loaded nanoliposomes, as compared to controls. Thus, our data highlight the potential use of salmon lecithin-derived RGD peptide PEGylated nanoliposomes for the efficient drug delivery of curcumin as a neuroprotective agent.

Application of transcranial brain stimulation in dementia

The number of patients with dementia grows rapidly as the global population ages, which posits tremendous health-care burden to the society. Only cholinesterase inhibitors and a N-methyl-D-aspartate receptor antagonist have been approved for treating patients with Alzheimer's disease (AD), and their clinical effects remained limited. Medical devices serve as an alternative therapeutic approach to modulating neural activities and enhancing cognitive function. Four major brain stimulation technologies including deep brain stimulation (DBS), transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), and transcranial ultrasound stimulation (TUS) have been applied to AD in a clinical trial setting. DBS allows electrical stimulation at the specified nucleus but remains resource-demanding, and after all, an invasive surgery; whereas TMS and tDCS are widely available and affordable but less ideal with respect to localization. The unique physical property of TUS, on the other hand, allows both thermal and mechanical energy to be transduced and focused for neuromodulation. In the context of dementia, using focused ultrasound to induce blood-brain barrier opening for delivering drugs and metabolizing amyloid protein has drawn great attention in recent years. Furthermore, low-intensity pulsed ultrasound has demonstrated its neuroprotective effects in both in vitro and in vivo studies, leading to ongoing clinical trials for AD. The potential and limitation of transcranial brain stimulation for treating patients with dementia would be discussed in this review.

Treatment of Alzheimer's Disease: Beyond Symptomatic Therapies

In an ever-increasing aged world, Alzheimer's disease (AD) represents the first cause of dementia and one of the first chronic diseases in elderly people. With 55 million people affected, the WHO considers AD to be a disease with public priority. Unfortunately, there are no final cures for this pathology. Treatment strategies are aimed to mitigate symptoms, i.e., acetylcholinesterase inhibitors (AChEI) and the N-Methyl-D-aspartate (NMDA) antagonist Memantine. At present, the best approaches for managing the disease seem to combine pharmacological and non-pharmacological therapies to stimulate cognitive reserve. Over the last twenty years, a number of drugs have been discovered acting on the well-established biological hallmarks of AD, deposition of β-amyloid aggregates and accumulation of hyperphosphorylated tau protein in cells. Although previous efforts disappointed expectations, a new era in treating AD has been working its way recently. The Food and Drug Administration (FDA) gave conditional approval of the first disease-modifying therapy (DMT) for the treatment of AD, aducanumab, a monoclonal antibody (mAb) designed against Aβ plaques and oligomers in 2021, and in January 2023, the FDA granted accelerated approval for a second monoclonal antibody, Lecanemab. This review describes ongoing clinical trials with DMTs and non-pharmacological therapies. We will also present a future scenario based on new biomarkers that can detect AD in preclinical or prodromal stages, identify people at risk of developing AD, and allow an early and curative treatment.

Are Protective Activities and Limitations in Practical Skills of Daily Living Associated with the Cognitive Performance of People with Mild Cognitive Impairment? Baseline Results from the BrainFit-Nutrition Study

Limitations in daily living have not yet been described adequately for mild cognitive impairment (MCI). In this study, we investigated first, time spent on protective activities (social, mental, and physical) and second, limitations in practical skills of daily living, both for people with MCI. We used baseline data from 270 individuals who participated in the randomized controlled trial BrainFit-Nutrition. The Montreal Cognitive Assessment (MoCA) was used to identify people with MCI. Participants were asked how much time they spent engaged in social, mental, and physical activities each week. Furthermore, the Bayer-ADL scale was used to quantify deficits in activities of daily living (ADLs). Regarding protection, the number of hours spent engaged in the three activity areas was significantly correlated with the cognitive performance in people with MCI. Social activities were positively associated with current cognitive performance. Concerning the limitations in practical skills of daily living, older and more cognitively impaired individuals were affected. Memory and orientation appear to be among the first practical skills of daily living that become impaired in people with MCI. Treatment recommendations for people with MCI include an increase in social, mental, and physical activities as well as the promotion of a healthy lifestyle.

IL-33/ST2 signaling pathway and Alzheimer's disease: A systematic review and meta-analysis

The IL-33/ST2 signaling pathway has potential relevance for clinical identification and treatment of Alzheimer's disease (AD). Here, eight databases (including CNKI, Wanfang, SinoMed, VIP, PubMed, Cochrane library, Embase and Web of Science) were employed to search for studies on IL-33/ST2 signaling pathway and its association with AD. Totally, 15 articles were included, of which 5 studies investigated the connection between IL-33 gene polymorphisms and AD, 4 studies explored the serum IL-33 and sST2 levels in patients with AD and Mild cognitive impairment (MCI), and the exact mechanisms underlying IL-33/ST2 signaling pathway in AD were explored in 6 studies. Then, the RevMan 5.4 software was used for meta-analysis, and the related studies were systematically reviewed. The results of the meta-analysis showed that serum IL-33 levels were higher in patients with AD and MCI than in healthy controls (HC), with serum IL-33 levels in AD patients significantly higher than in MCI patients (SMD = 0.26, 95 % CI: 0.02, 0.51; P = 0.04). Compared with HC, the sST2 level was significantly higher in AD patients (SMD = 1.23, 95 % CI: 0.93, 1.53; P < 0.00001) and tended to elevate in patients with MCI. The systematic review indicated that there is a significant relationship between IL-33 gene polymorphisms and susceptibility to AD; The IL-33/ST2 signaling pathway may be one of the future treatment targets for AD. Our study provides evidence to prove that serum IL-33 and sST2 have potential clinical application value as biomarkers for identifying AD.