Short-Term Response to Cholinesterase Inhibitors in Alzheimer's Disease Delays Time to Nursing Home Placement

Exploring the Mechanisms and Therapeutic Approaches of Mitochondrial Dysfunction in Alzheimer's Disease: An Educational Literature Review

Alzheimer's disease (AD) presents a significant challenge to global health. It is characterized by progressive cognitive deterioration and increased rates of morbidity and mortality among older adults. Among the various pathophysiologies of AD, mitochondrial dysfunction, encompassing conditions such as increased reactive oxygen production, dysregulated calcium homeostasis, and impaired mitochondrial dynamics, plays a pivotal role. This review comprehensively investigates the mechanisms of mitochondrial dysfunction in AD, focusing on aspects such as glucose metabolism impairment, mitochondrial bioenergetics, calcium signaling, protein tau and amyloid-beta-associated synapse dysfunction, mitophagy, aging, inflammation, mitochondrial DNA, mitochondria-localized microRNAs, genetics, hormones, and the electron transport chain and Krebs cycle. While lecanemab is the only FDA-approved medication to treat AD, we explore various therapeutic modalities for mitigating mitochondrial dysfunction in AD, including antioxidant drugs, antidiabetic agents, acetylcholinesterase inhibitors (FDA-approved to manage symptoms), nutritional supplements, natural products, phenylpropanoids, vaccines, exercise, and other potential treatments.

Treatment of Alzheimer Disease

OBJECTIVE

Symptom-oriented treatment has been the mainstay of Alzheimer disease (AD) pharmacotherapy for decades. This article reviews the evidence basis for symptomatic treatments for AD and the emerging data on amyloid-lowering therapies with possible disease-slowing effects.

LATEST DEVELOPMENT

Amyloid-lowering monoclonal antibody therapies entered clinical use in 2021. In July 2023, lecanemab became the first of these to gain full US Food and Drug Administration (FDA) approval and limited Medicare payment coverage. Donanemab gained similar approval status in July 2024. The approved agents remove amyloid plaque from the brain and appear to slow clinical disease progression but can produce significant adverse events known as amyloid-related imaging abnormalities with cerebral edema or effusion and with cerebral hemorrhages. Extensive safety monitoring is therefore required, including scheduled MRI scans. Also in 2023, brexpiprazole became the first agent specifically approved by the FDA for agitation associated with AD. Suvorexant, an orexin receptor antagonist, previously was approved for the treatment of insomnia in people with mild and moderate AD.

ESSENTIAL POINTS

There is robust evidence for the use of acetylcholinesterase inhibitors for patients with mild, moderate, and severe dementia due to AD, including outcomes beyond changes in cognitive screening test scores. More limited studies support the use of memantine in moderate and severe stages. These agents have a primary effect of delaying decline in cognition and function and postponing the emergence of adverse behaviors. Pharmacotherapy for behavioral and psychological symptoms is less predictable, and most clinical trials have had negative results. Anti-amyloid therapies provide the first FDA-approved option to alter AD pathology, but an understanding of overall utility and value to patients remains in its infancy.

The Case for a Novel Therapeutic Approach to Dementia: Small Molecule Hepatocyte Growth Factor (HGF/MET) Positive Modulators

An estimated 6.5 million Americans aged 65 years or older have Alzheimer's disease (AD), which will grow to 13.8 million Americans by 2060. Despite the growing burden of dementia, no fundamental change in drug development for AD has been seen in > 20 years. Currently approved drugs for AD produce only modest symptomatic improvements in cognition with small effect sizes. A growing mismatch exists between the urgent need to develop effective drugs for symptomatic AD and the largely failed search for disease modification. The failure rate of clinical trials in AD is high overall, and in particular for disease-modifying therapies. Research efforts in AD have focused predominantly on amyloid-β and tau pathologies, but limiting clinical research to these "classical hallmarks" of the disease does not address the most urgent patient, caregiver, or societal needs. Rather, clinical research should consider the complex pathophysiology of AD. Innovative approaches are needed that provide outside-the-box thinking, and re-imagine trial design, interventions, and outcomes as well as progress in proteomics and fluid biomarker analytics for both diagnostics and disease monitoring. A new approach offering a highly specific, yet multi-pronged intervention that exerts positive modulation on the HGF/MET neurotrophic system is currently being tested in mid-to-late-stage clinical trials in mild to moderate AD. Findings from such trials may provide data to support novel approaches for development of innovative drugs for treating AD at various disease stages, including among patients already symptomatic, and may offer benefits for other neurodegenerative diseases.

Predictors of response to acetylcholinesterase inhibitors in dementia: A systematic review

Background

The mainstay of therapy for many neurodegenerative dementias still relies on acetylcholinesterase inhibitors (AChEI); however, there is debate on various aspects of such treatment. A huge body of literature exists on possible predictors of response, but a comprehensive review is lacking. Therefore, our aim is to perform a systematic review of the predictors of response to AChEI in neurodegenerative dementias, providing a categorization and interpretation of the results.

Methods

We conducted a systematic review of the literature up to December 31st, 2021, searching five different databases and registers, including studies on rivastigmine, donepezil, and galantamine, with clearly defined criteria for the diagnosis of dementia and the response to AChEI therapy. Records were identified through the string: predict * AND respon * AND (acetylcholinesterase inhibitors OR donepezil OR rivastigmine OR galantamine). The results were presented narratively.

Results

We identified 1,994 records in five different databases; after exclusion of duplicates, title and abstract screening, and full-text retrieval, 122 studies were finally included.

Discussion

The studies show high heterogeneity in duration, response definition, drug dosage, and diagnostic criteria. Response to AChEI seems associated with correlates of cholinergic deficit (hallucinations, fluctuating cognition, substantia innominate atrophy) and preserved cholinergic neurons (faster alpha on REM sleep EEG, increased anterior frontal and parietal lobe perfusion after donepezil); white matter hyperintensities in the cholinergic pathways have shown inconsistent results. The K-variant of butyrylcholinesterase may correlate with better response in late stages of disease, while the role of polymorphisms in other genes involved in the cholinergic system is controversial. Factors related to drug availability may influence response; in particular, low serum albumin (for donepezil), CYP2D6 variants associated with reduced enzymatic activity and higher drug doses are the most consistent predictors, while AChEI concentration influence on clinical outcomes is debatable. Other predictors of response include faster disease progression, lower serum cholesterol, preserved medial temporal lobes, apathy, absence of concomitant diseases, and absence of antipsychotics. Short-term response may predict subsequent cognitive response, while higher education might correlate with short-term good response (months), and long-term poor response (years). Age, gender, baseline cognitive and functional levels, and APOE relationship with treatment outcome is controversial.

Long-term Effects of Cholinesterase Inhibitors on Cognitive Decline and Mortality

Objective

To investigate whether cholinesterase inhibitors (ChEIs) are associated with slower cognitive decline in Alzheimer dementia and decreased risk of severe dementia or death.

Methods

Patients with Alzheimer dementia from the Swedish Dementia Registry starting on ChEIs within 3 months of the dementia diagnosis were included and compared to nontreated patients with Alzheimer dementia. In a propensity score–matched cohort, the association between ChEI use and cognitive trajectories assessed by Mini-Mental State Examination (MMSE) scores was examined with a mixed model, and severe dementia (MMSE score <10) or death as an outcome was assessed with Cox proportional hazards models.

Results

The matched cohort included 11,652 ChEI users and 5,826 nonusers. During an average of 5 years of follow-up, 255 cases developed severe dementia, and 6,055 (35%) died. ChEI use was associated with higher MMSE score at each visit (0.13 MMSE points per year; 95% confidence interval [CI] 0.06–0.20). ChEI users had a 27% lower risk of death (0.73, 95% CI 0.69–0.77) compared with nonusers. Galantamine was associated with lower risk of death (0.71, 95% CI 0.65–0.76) and lower risk of severe dementia (0.69, 95% CI 0.47–1.00) and had the strongest effect on cognitive decline of all the ChEIs (0.18 MMSE points per year, 95% CI 0.07–0.28).

Conclusions

ChEIs are associated with cognitive benefits that are modest but persist over time and with reduced mortality risk, which could be explained partly by their cognitive effects. Galantamine was the only ChEI demonstrating a significant reduction in the risk of developing severe dementia.

Classification of Evidence

This study provides Class III evidence that for patients with Alzheimer dementia ChEIs decrease long-term cognitive decline and risk of death and that galantamine decreases the risk of severe dementia.

Prescribing medications of questionable benefit prior to death: a retrospective study on older nursing home residents with and without dementia in Germany

Purpose

We studied the prevalence of medications of questionable benefit in the last 6 months of life among older nursing home residents with and without dementia in Germany.

Methods

A retrospective cohort study was conducted on claims data from 67,328 deceased nursing home residents aged 65+ years who were admitted between 2010 and 2014. We analyzed prescription regimens of medications of questionable benefit in the 180–91-day period and the 90-day period prior to death for residents with dementia (n = 29,052) and without dementia (n = 38,276). Factors associated with new prescriptions of medications of questionable benefit prior to death were analyzed using logistic regression models among all nursing home residents and stratified by dementia.

Results

A higher proportion of nursing home residents with dementia were prescribed at least one medication of questionable benefit in the 180–91-day (29.6%) and 90-day (26.8%) periods prior to death, compared with residents without dementia (180–91 days, 22.8%; 90 days, 20.1%). Lipid-lowering agents were the most commonly prescribed medications. New prescriptions of medications of questionable benefit were more common among residents with dementia (9.8% vs. 8.7%). When excluding anti-dementia medication, new prescriptions of these medications were more common among residents without dementia (6.4% vs. 8.0%). The presence of dementia (odds ratio [OR] 1.40, 95% confidence interval [95%CI] 1.32–1.48) and excessive polypharmacy were associated with new prescriptions of medications of questionable benefit prior to death (OR 4.74, 95%CI 4.15–5.42).

Conclusion

Even when accounting for anti-dementia prescriptions, the prevalence of nursing home residents with dementia receiving medications of questionable benefit is considerable and may require further attention.

Electronic supplementary material

The online version of this article (10.1007/s00228-020-02859-3) contains supplementary material, which is available to authorized users.

Alzheimer's disease medication and outcomes of hospitalisation among patients with dementia

AIMS

The use of Alzheimer disease medication for the treatment of dementia symptoms has shown significant benefits with regards to functional and cognitive outcomes as well as nursing home placement (NHP) and mortality. Hospitalisations in these patient groups are characterised by extended length of stays (LOS), frequent readmissions, frequent NHP and high-mortality rates. The impact of Alzheimer disease medication on the aforementioned outcomes remains still unknown. This study assessed the association of Alzheimer disease medication with outcomes of hospitalisation among patients with Alzheimer disease and other forms of dementia.

METHODS

A dynamic retrospective cohort study from 2004 to 2015 was conducted which claims data from a German health insurance company. People with dementia (PWD) were identified using ICD-10 codes and diagnostic measures. The main predictor of interest was the use of Alzheimer disease medication. Hospitalisation outcomes included LOS, readmissions, NHP and mortality during and after hospitalisation across four hospitalisations. Confounding was addressed using a propensity score throughout all analyses.

RESULTS

A total of 1380 users of Alzheimer disease medication and 6730 non-users were identified. The use of Alzheimer disease medication was associated with significantly shorter LOS during the first hospitalisations with estimates for the second, third and fourth showed a tendency towards shorter hospital stays. In addition, current users of Alzheimer disease medication had a lower risk of hospital readmission after the first two hospitalisations. These associations were not significant for the third and fourth hospitalisations. Post-hospitalisation NHP and mortality rates also tended to be lower among current users than among non-users but differences did not reach statistical significance.

CONCLUSIONS

Our results indicate that Alzheimer disease medication might contribute to a reduction of the LOS and the number of readmissions in PWD.