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Fulltext Diagnosis and management of Alzheimer's disease--an update

Srinivas P

Med J Malaysia, 1999 Dec;54(4):541-9; quiz 550.
PMID: 11072482

Alzheimer's disease (AD) has become recognised as a major cause of morbidity and mortality in the ageing population worldwide. Over 20 million people worldwide are affected by AD, which ensures that the disease imposes a major economic burden. Alzheimer's disease is a progressive neurodegenerative disorder with characteristic clinical and neuropathological features. Neurofibrillary tangles, neuritic plaques and amyloid angiopathy occur in varying severity in brains of patient's with Alzheimer's disease. Biological markers of AD allowing an early definitive premorbid diagnoses are currently not available. Memory loss for recent events is invariable and often the earliest prominent symptom. Language disorders, difficulties with complex tasks, depression, psychotic symptoms and behavioral changes are other common manifestations of AD. Diagnosis involves the early detection of cognitive decline and ruling out other causes of dementia like vascular dementia, Lewy body dementia, fronto-temporal degeneration or reversible causes like hypothyroidism. Acetylcholinesterase inhibitors have shown to be effective in mild to moderate AD in improving the cognitive function of patients in clinical trials. Caregiver intervention programs have considerable potential to improve both the caregiver and patient quality of life.

Matched MeSH terms: Alzheimer Disease/psychology
Memory and time: Backward and forward telescoping in Alzheimer's disease

El Haj M, Janssen SMJ, Antoine P

Brain Cogn, 2017 10;117:65-72.
PMID: 28629646 DOI: 10.1016/j.bandc.2017.06.005

Backward and forward telescoping are opposite timing biases. The former refers to misattributing events to earlier dates, whereas the latter refers to misattributing events to later dates. The present study investigated both biases in participants with Alzheimer's Disease (AD) and healthy older adults, matched on age, sex, and education level. Participants were asked to recall the years when five remote and five recent public events had occurred. They were also assessed with a cognitive and clinical battery that included a context memory task on which they had to associate letters and locations. Results showed backward telescoping for recent events and forward telescoping for remote events in AD participants and older adults. Furthermore, poorer context recall was observed in AD participants and older adults displaying backward telescoping than in those displaying forward telescoping. These findings suggest an association between the amount of contextual information recalled and the direction of the timing bias. Backward telescoping can be associated with deficiencies in retrieving context characteristics of events, which have been associated with retrograde amnesia and pathological changes to the hippocampus in AD.

Matched MeSH terms: Alzheimer Disease/psychology*
Fulltext APOE, TOMM40, and sex interactions on neural network connectivity

Li T, Pappas C, Le ST, Wang Q, Klinedinst BS, Larsen BA, et al.

Neurobiol Aging, 2022 Jan;109:158-165.
PMID: 34740077 DOI: 10.1016/j.neurobiolaging.2021.09.020

The Apolipoprotein E ε4 (APOE ε4) haplotype is the strongest genetic risk factor for late-onset Alzheimer's disease (AD). The Translocase of Outer Mitochondrial Membrane-40 (TOMM40) gene maintains cellular bioenergetics, which is disrupted in AD. TOMM40 rs2075650 ('650) G versus A carriage is consistently related to neural and cognitive outcomes, but it is unclear if and how it interacts with APOE. We examined 21 orthogonal neural networks among 8,222 middle-aged to aged participants in the UK Biobank cohort. ANOVA and multiple linear regression tested main effects and interactions with APOE and TOMM40 '650 genotypes, and if age and sex acted as moderators. APOE ε4 was associated with less strength in multiple networks, while '650 G versus A carriage was related to more language comprehension network strength. In APOE ε4 carriers, '650 G-carriage led to less network strength with increasing age, while in non-G-carriers this was only seen in women but not men. TOMM40 may shift what happens to network activity in aging APOE ε4 carriers depending on sex.

Matched MeSH terms: Alzheimer Disease/psychology
Fulltext Predicting probable Alzheimer's disease using linguistic deficits and biomarkers

Orimaye SO, Wong JS, Golden KJ, Wong CP, Soyiri IN

BMC Bioinformatics, 2017 Jan 14;18(1):34.
PMID: 28088191 DOI: 10.1186/s12859-016-1456-0

BACKGROUND: The manual diagnosis of neurodegenerative disorders such as Alzheimer's disease (AD) and related Dementias has been a challenge. Currently, these disorders are diagnosed using specific clinical diagnostic criteria and neuropsychological examinations. The use of several Machine Learning algorithms to build automated diagnostic models using low-level linguistic features resulting from verbal utterances could aid diagnosis of patients with probable AD from a large population. For this purpose, we developed different Machine Learning models on the DementiaBank language transcript clinical dataset, consisting of 99 patients with probable AD and 99 healthy controls.
RESULTS: Our models learned several syntactic, lexical, and n-gram linguistic biomarkers to distinguish the probable AD group from the healthy group. In contrast to the healthy group, we found that the probable AD patients had significantly less usage of syntactic components and significantly higher usage of lexical components in their language. Also, we observed a significant difference in the use of n-grams as the healthy group were able to identify and make sense of more objects in their n-grams than the probable AD group. As such, our best diagnostic model significantly distinguished the probable AD group from the healthy elderly group with a better Area Under the Receiving Operating Characteristics Curve (AUC) using the Support Vector Machines (SVM).
CONCLUSIONS: Experimental and statistical evaluations suggest that using ML algorithms for learning linguistic biomarkers from the verbal utterances of elderly individuals could help the clinical diagnosis of probable AD. We emphasise that the best ML model for predicting the disease group combines significant syntactic, lexical and top n-gram features. However, there is a need to train the diagnostic models on larger datasets, which could lead to a better AUC and clinical diagnosis of probable AD.

Matched MeSH terms: Alzheimer Disease/psychology
Lingzhi or Reishi Medicinal Mushroom, Ganoderma lucidum (Agaricomycetes), Ameliorates Nonspatial Learning and Memory Deficits in Rats with Hypercholesterolemia and Alzheimer's Disease

Rahman MA, Hossain S, Abdullah N, Aminudin N

Int J Med Mushrooms, 2020;22(11):1067-1078.
PMID: 33426838 DOI: 10.1615/IntJMedMushrooms.2020036354

Alzheimer's disease (AD) is the leading neurodegenerative disorder affecting memory and learning of aged people. Hypercholesterolemia had been implicated as one of the stark hallmarks of AD. Recent AD control guidelines have suggested lifestyle modification to slow down the progression of AD. In this regard, medicinal mushroom Ganoderma lucidum seems apt. In the present study, hot water extract of G. lucidum (200 mg/kg body weight) was fed to the hypercholesterolemic and AD model rats for 8 weeks. Nonspatial memory and learning abilities of the model animals was assessed using novel object recognition (NOR) test, rotarod test, and locomotor/open-field test. Then, the animals were sacrificed and transmission electron micrograph (TEM) view of the hippocampal neurons was assessed. In all the nonspatial memory and learning tests, the G. lucidum HWE fed rats performed better indicating improved memory and learning abilities. TEM view showed regular arrangement of the neurons in the G. lucidum HWE fed rats compared with those of the deranged arrangement of the AD rats. G. lucidum might have aided in restoring the memory and learning abilities of the AD model animals through maintaining neuronal structure and function. Thus, G. lucidum could be suggested as a medicotherapeutic agent against AD.

Matched MeSH terms: Alzheimer Disease/psychology*
Fulltext A Review on the Relationship between Tocotrienol and Alzheimer Disease

Chin KY, Tay SS

Nutrients, 2018 Jul 09;10(7).
PMID: 29987193 DOI: 10.3390/nu10070881

Alzheimer’s disease (AD) is plaguing the aging population worldwide due to its tremendous health care and socioeconomic burden. Current treatment of AD only offers symptomatic relief to patients. Development of agents targeting specific pathologies of AD is very slow. Tocotrienol, a member of the vitamin E family, can tackle many aspects of AD, such as oxidative stress, mitochondrial dysfunction and abnormal cholesterol synthesis. This review summarizes the current evidence on the role of tocotrienol as a neuroprotective agent. Preclinical studies showed that tocotrienol could reduce oxidative stress by acting as a free-radical scavenger and promoter of mitochondrial function and cellular repair. It also prevented glutamate-induced neurotoxicity in the cells. Human epidemiological studies showed a significant inverse relationship between tocotrienol levels and the occurrence of AD. However, there is no clinical trial to support the claim that tocotrienol can delay or prevent the onset of AD. As a conclusion, tocotrienol has the potential to be developed as an AD-preventing agent but further studies are required to validate its efficacy in humans.

Matched MeSH terms: Alzheimer Disease/psychology
A molecular approach in drug development for Alzheimer's disease

Agatonovic-Kustrin S, Kettle C, Morton DW

Biomed Pharmacother, 2018 Oct;106:553-565.
PMID: 29990843 DOI: 10.1016/j.biopha.2018.06.147

An increase in dementia numbers and global trends in population aging across the world prompts the need for new medications to treat the complex biological dysfunctions, such as neurodegeneration associated with dementia. Alzheimer's disease (AD) is the most common form of dementia. Cholinergic signaling, which is important in cognition, is slowly lost in AD, so the first line therapy is to treat symptoms with acetylcholinesterase inhibitors to increase levels of acetylcholine. Out of five available FDA-approved AD medications, donepezil, galantamine and rivastigmine are cholinesterase inhibitors while memantine, a N-methyl d-aspartate (NMDA) receptor antagonist, blocks the effects of high glutamate levels. The fifth medication consists of a combination of donepezil and memantine. Although these medications can reduce and temporarily slow down the symptoms of AD, they cannot stop the damage to the brain from progressing. For a superior therapeutic effect, multi-target drugs are required. Thus, a Multi-Target-Directed Ligand (MTDL) strategy has received more attention by scientists who are attempting to develop hybrid molecules that simultaneously modulate multiple biological targets. This review highlights recent examples of the MTDL approach and fragment based strategy in the rational design of new potential AD medications.

Matched MeSH terms: Alzheimer Disease/psychology