Synthesis and comparison of the meta-analyses evaluating the efficacy of memantine in moderate to severe stages of Alzheimer's disease

Unit information prior for adaptive information borrowing from multiple historical datasets

In clinical trials, there often exist multiple historical studies for the same or related treatment investigated in the current trial. Incorporating historical data in the analysis of the current study is of great importance, as it can help to gain more information, improve efficiency, and provide a more comprehensive evaluation of treatment. Enlightened by the unit information prior (UIP) concept in the reference Bayesian test, we propose a new informative prior called UIP from an information perspective that can adaptively borrow information from multiple historical datasets. We consider both binary and continuous data and also extend the new UIP to linear regression settings. Extensive simulation studies demonstrate that our method is comparable to other commonly used informative priors, while the interpretation of UIP is intuitive and its implementation is relatively easy. One distinctive feature of UIP is that its construction only requires summary statistics commonly reported in the literature rather than the patient-level data. By applying our UIP to phase III clinical trials for investigating the efficacy of memantine in Alzheimer's disease, we illustrate its ability to adaptively borrow information from multiple historical datasets. The Python codes for simulation studies and the real data application are available at https://github.com/JINhuaqing/UIP.

The treatment of cognitive dysfunction in dementia: a multiple treatments meta-analysis

OBJECTIVE

No cure is currently available for dementia; however, various treatments and interventions have been reported to be effective. The factors influencing the efficacy of dementia treatment have not been comprehensively evaluated. This study evaluated the factors influencing treatment effects on cognitive dysfunction in dementia by comparing the results obtained from a meta-analysis based on meta-regression.

METHODS

We searched for articles, clinical trials, and meta-analyses on the efficacy of pharmacotherapy or psychosocial treatment for dementia published between 2000 and 2016 in the MEDLINE/PubMed, Cochrane Library, SCOPUS, and Airiti Library databases.

RESULTS

The 235 selected studies involved 44,854 patients with dementia (mainly vascular dementia, Alzheimer disease, and mild cognitive impairment). A preliminary random effects meta-analysis yielded a positive overall effect. The pooled standardized mean difference of the treatment effects on cognitive dysfunction was 0.439 (95% confidence interval 0.374, 0.504). The results of meta-regression showed that in young patients (β = - 0.036, p value < 0.001) with vascular dementia (β = 0.603, p value < 0.001), the efficacies of treatment 2 (symptomatic treatment for vascular dementia with piracetam, nimodipine, aniracetam, flunarizine, vinpocetine, hyperbaric oxygen, oxiracetam, or EGB761) and treatment 5 (treatment with other alternative therapies including acupuncture, premarin, statin, butylphthalide soft capsules, donepezil, huperzine A, and lithium treatment) were higher than those of other existing treatments for cognitive dysfunction (β = 0.308 and 0.321, p values = 0.010 and < 0.001, respectively).

CONCLUSION

The most effective intervention for dementia available is symptomatic treatment for vascular dementia. Antipsychotic treatment for dementia alleviates cognitive dysfunction less effectively than does symptomatic treatment. Alternative therapies are also effective at present. Further research on causes and very early diagnosis of Alzheimer disease is warranted.

Can Salivary Acetylcholinesterase be a Diagnostic Biomarker for Alzheimer?

INTRODUCTION

The loss of brain cholinergic activity is a key phenomenon in the biochemistry of Alzheimer's Disease (AD). Due to the specific biosynthesis of Acetylcholinesterase (AChE) of cholinergic neurons, the enzyme has been proposed as a potential biochemical marker of cholinergic activity. AChE is expressed not only in the Central Nervous System (CNS), Peripheral Nervous System (PNS) and muscles, but also on the surface of blood cells and saliva.

AIM

This study aimed to measure salivary AChE activity in AD and to determine the feasibility of creating a simple laboratory test for diagnosing such patients.

MATERIALS AND METHODS

In this cross-sectional study, the recorded data were obtained from 15 Alzheimer's patients on memantine therapy and 15 healthy subjects. Unstimulated whole saliva samples were collected from the participants and salivary levels of AChE activity were determined by using the Ellman colorimetric method. The Mann Whitney U test was used to compare the average (median) of AChE activity between AD and controls. In order to adjust for possible confounding factors, partial correlation coefficient and multivariate linear regressions were used.

RESULTS

Although the average of AChE activity in the saliva of people with AD was lower compared to the control group, we found no statistically significant differences using Mann Whitney U test (138 in control group vs. 175 in Alzheimer's patients, p value=0.25). Additionally, no significant differences were observed in the activity of this enzyme in both sexes or with increased age or duration of the disease. After adjusting for age and gender, there was no association between AChE activity and AD (regression coefficient β=0.08; p value= 0.67).

CONCLUSION

Saliva AChE activity was not significantly associated with AD. This study might help in introduce a new diagnostic aid for AD or monitor patients with AD.

[Memantine in treatment of Alzheimer's disease: 20 years of clinical use]

Alzheimer's disease (AD) is a common neurodegenerative disease with progressive course which leads to severe dementia. The author considers the issues of pathogenesis and diagnosis of AD. The efficacy and safety of memantine are analyzed in depth. Recommendations for clinicians on the use of memantine in patients with AD are presented.

Pharmacotherapeutic strategies in the treatment of severe Alzheimer's disease

INTRODUCTION

Alzheimer's disease (AD) is a slowly progressive neurodegenerative disease. Patients with severe AD often require assistance with daily functioning and have a substantially higher probability of admission to nursing homes compared to the general population.

AREAS COVERED

Medications approved by the US Food and Drug Administration for the treatment of severe AD include the cholinesterase inhibitors (ChEIs), donepezil (10 and 23 mg/day) and rivastigmine (transdermal patch, 13.3 mg/24 hours), and the N-methyl-D-aspartate receptor antagonist memantine (immediate- and extended-release formulations). This article will review the efficacy, safety, and tolerability data of these agents in the treatment of severe AD. Issues related to combination therapy, neuropsychiatric symptoms, and treatment discontinuation are also discussed.

EXPERT OPINION

AD therapeutics provide benefits on measures of cognition, functioning, behavior, and global status even in the severe stages of AD. Combination therapy with memantine and ChEIs may provide additive benefits compared with ChEI monotherapy. Decisions regarding discontinuation of these medications should be made on a case-by-case basis, with some evidence suggesting that discontinuation may worsen cognition and functional impairment. It is recommended that patients entering the terminal stages of AD discontinue all medications not necessary for comfort.

Disruption of thalamic connectivity in Alzheimer's disease: a diffusion tensor imaging study

The aim of this study was to evaluate the structural integrity of the thalamic connectivity of specific fiber tracts in different stages of Alzheimer's disease (AD) using diffusion tensor imaging (DTI). Thirty-five patients with AD and 22 normal control (NC) subjects were recruited. Based on Mini Mental State Examination score, the AD patients were divided into three subgroups for comparison with the NC group: mild (mi-AD, n = 14), moderate (mo-AD, n = 12), and severe (se-AD, n = 9) AD. The fornix (FX), anterior thalamic radiation (ATR), and posterior thalamic radiation (PTR) were selected to represent the thalamic connectivity with other brain regions. The fornix was divided into the column and body of the fornix (FX-1) and the bilateral fornix (crus)/stria terminalis (FX-2/ST) based on the atlas. Through the atlas-based analysis and fiber tracking method, we measured fractional anisotropy (FA), mean diffusivity (MD), and tract volume to reflect the microstructural and macrostructural changes of these fibers during AD progression. There were significant differences in the FA and MD of all fibers, except the right PTR, between the AD and NC subjects. Further subgroup analyses revealed that the mi-AD subgroup had decreased FA only in the FX-1 and increased MD in the FX-1 and bilateral ATR, the mo-AD subgroup showed declined FA and increased MD in the FX-1, bilateral FX-2/ST and ATR; the se-AD subgroup exhibited lower FA and higher MD values in all fibers except the right PTR. We also found reduced tract volume values in the FX and left ATR in the AD patients. Further subgroup analyses revealed that these differences only existed in the se-AD patients. Our DTI analyses indicate that the integrity of thalamic connectivity is progressively disrupted following cognitive decline in AD and that DTI parameters in the column and body of the fornix show promise as potential markers for the early diagnosis of AD and for monitoring disease progression.

Slowing the progression of Alzheimer's disease; what works?

Alzheimer's disease (AD) is an age-related progressive dementia, which is increasing in prevalence world-wide. Typically affecting short-term memory at onset, this devastating illness advances to impair all aspects of cognition, as well as non-cognitive domains. Although much effort has been made in recent years to develop disease-modifying treatments, medications which provided promising results in pre-clinical research have so far faltered in human clinical trials. Attention has recently shifted into trying to identify preventative measures that may delay the onset of the illness. Preventative factors include physical activity, proper diet, cognitive stimulation and the management of conditions such as hypertension, diabetes and obesity. However, it remains imperative to identify approaches that may help patients already diagnosed with the illness. Alongside pharmacological research, much work has been done on uncovering strategies which may slow down the progression of AD. This review aims to summarize evidence supporting or refuting methods impacting on the progression of the disease. AD remains a chronic and serious condition, therefore any intervention delaying the onset of moderate/severe symptoms will have a significant impact on patients and their families.

Melanocortin receptor agonist ACTH 1-39 protects rat forebrain neurons from apoptotic, excitotoxic and inflammation-related damage

Patients with relapsing-remitting multiple sclerosis (RRMS) are commonly treated with high doses of intravenous corticosteroids (CS). ACTH 1-39, a member of the melanocortin family, stimulates production of CS by the adrenals, but melanocortin receptors are also found in the central nervous system (CNS) and on immune cells. ACTH is produced within the CNS and may have direct protective effects on glia and neurons independent of CS. We previously reported that ACTH 1-39 protected oligodendroglia (OL) and their progenitors (OPC) from a panel of excitotoxic and inflammation-related agents. Neurons are the most vulnerable cells in the CNS. They are terminally differentiated, and sensitive to inflammatory and excitotoxic insults. For potential therapeutic protection of gray matter, it is important to investigate the direct effects of ACTH on neurons. Cultures highly enriched in neurons were isolated from 2-3 day old rat brain. After 4-7 days in culture, the neurons were treated for 24h with selected toxic agents with or without ACTH 1-39. ACTH 1-39 protected neurons from death induced by staurosporine, glutamate, NMDA, AMPA, kainate, quinolinic acid, reactive oxygen species and, to a modest extent, from rapidly released NO, but did not protect against kynurenic acid or slowly released nitric oxide. Our results show that ACTH 1-39 protects neurons in vitro from several apoptotic, excitotoxic and inflammation-related insults.

Pharmaceuticals that contain polycyclic hydrocarbon scaffolds

This review comprehensively explores approved pharmaceutical compounds that contain polycyclic scaffolds and the properties that these skeletons convey.

Herpes simplex virus type 1 and Alzheimer's disease: increasing evidence for a major role of the virus

Herpes simplex virus type 1 (HSV1), when present in brain of carriers of the type 4 allele of the apolipoprotein E gene (APOE), has been implicated as a major factor in Alzheimer's disease (AD). It is proposed that virus is normally latent in many elderly brains but reactivates periodically (as in the peripheral nervous system) under certain conditions, for example stress, immunosuppression, and peripheral infection, causing cumulative damage and eventually development of AD. Diverse approaches have provided data that explicitly support, directly or indirectly, these concepts. Several have confirmed HSV1 DNA presence in human brains, and the HSV1-APOE-ε4 association in AD. Further, studies on HSV1-infected APOE-transgenic mice have shown that APOE-e4 animals display a greater potential for viral damage. Reactivated HSV1 can cause direct and inflammatory damage, probably involving increased formation of beta amyloid (Aβ) and of AD-like tau (P-tau)-changes found to occur in HSV1-infected cell cultures. Implicating HSV1 further in AD is the discovery that HSV1 DNA is specifically localized in amyloid plaques in AD. Other relevant, harmful effects of infection include the following: dynamic interactions between HSV1 and amyloid precursor protein (APP), which would affect both viral and APP transport; induction of toll-like receptors (TLRs) in HSV1-infected astrocyte cultures, which has been linked to the likely effects of reactivation of the virus in brain. Several epidemiological studies have shown, using serological data, an association between systemic infections and cognitive decline, with HSV1 particularly implicated. Genetic studies too have linked various pathways in AD with those occurring on HSV1 infection. In relation to the potential usage of antivirals to treat AD patients, acyclovir (ACV) is effective in reducing HSV1-induced AD-like changes in cell cultures, and valacyclovir, the bioactive form of ACV, might be most effective if combined with an antiviral that acts by a different mechanism, such as intravenous immunoglobulin (IVIG).

Add-on prolonged-release melatonin for cognitive function and sleep in mild to moderate Alzheimer's disease: a 6-month, randomized, placebo-controlled, multicenter trial

Purpose

A link between poor sleep quality and Alzheimer’s disease (AD) has recently been suggested. Since endogenous melatonin levels are already reduced at preclinical AD stages, it is important to ask whether replenishing the missing hormone would be beneficial in AD and whether any such effects would be related to the presence of sleep disorder in patients.

Patients and methods

The effects of add-on prolonged-release melatonin (PRM) (2 mg) to standard therapy on cognitive functioning and sleep were investigated in 80 patients (men [50.7%], women [49.3%], average age 75.3 years [range, 52–85 years]) diagnosed with mild to moderate AD, with and without insomnia comorbidity, and receiving standard therapy (acetylcholinesterase inhibitors with or without memantine). In this randomized, double-blind, parallel-group study, patients were treated for 2 weeks with placebo and then randomized (1:1) to receive 2 mg of PRM or placebo nightly for 24 weeks, followed by 2 weeks placebo. The AD Assessment Scale–Cognition (ADAS-Cog), Instrumental Activities of Daily Living (IADL), Mini–Mental State Examination (MMSE), sleep, as assessed by the Pittsburgh Sleep Quality Index (PSQI) and a daily sleep diary, and safety parameters were measured.

Results

Patients treated with PRM (24 weeks) had significantly better cognitive performance than those treated with placebo, as measured by the IADL (P=0.004) and MMSE (P=0.044). Mean ADAS-Cog did not differ between the groups. Sleep efficiency, as measured by the PSQI, component 4, was also better with PRM (P=0.017). In the comorbid insomnia (PSQI ≥6) subgroup, PRM treatment resulted in significant and clinically meaningful effects versus the placebo, in mean IADL (P=0.032), MMSE score (+1.5 versus −3 points) (P=0.0177), and sleep efficiency (P=0.04). Median ADAS-Cog values (−3.5 versus +3 points) (P=0.045) were significantly better with PRM. Differences were more significant at longer treatment duration. PRM was well tolerated, with an adverse event profile similar to that of placebo.

Conclusion

Add-on PRM has positive effects on cognitive functioning and sleep maintenance in AD patients compared with placebo, particularly in those with insomnia comorbidity. The results suggest a possible causal link between poor sleep and cognitive decline.