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Alzheimer's

Breaking Down Brain Inflammation: Scientists Identify Key Enzyme in Alzheimer’s Disease

A research team has identified a previously unknown enzyme, SIRT2, that plays a key role in memory loss associated with Alzheimer’s disease (AD). The study provides critical insights into how astrocytes contribute to cognitive decline by producing excessive amounts of the inhibitory neurotransmitter GABA.

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As researchers continue to unravel the mysteries of Alzheimer’s disease (AD), a team at the Institute for Basic Science (IBS) has made a significant breakthrough. They have identified a previously unknown enzyme, SIRT2, that plays a crucial role in memory loss associated with AD. This discovery provides critical insights into how astrocytes contribute to cognitive decline by producing excessive amounts of the inhibitory neurotransmitter GABA.

Astrocytes, once thought to only support neurons, are now known to actively influence brain function. In AD, astrocytes become reactive, attempting to clear amyloid-beta (Aβ) plaques, a hallmark of the disease. However, this process triggers a harmful chain reaction, leading to the overproduction of GABA, which dampens brain activity and causes memory impairment.

The IBS research team used molecular analysis, microscopic imaging, and electrophysiology to identify SIRT2 as one of the critical enzymes involved in GABA overproduction in AD-affected astrocytes. They found that SIRT2 protein was increased in the astrocytes of a commonly used AD mouse model and in post-mortem human AD patient brains.

“When we inhibited the astrocytic expression of SIRT2 in AD mice, we observed partial recovery of memory and reduced GABA production,” said Mridula Bhalla, the lead author of the study. “While we expected reduced GABA release, we found that only short-term working memory was recovered, and spatial memory was not. This was exciting but also left us with more questions.”
The research team’s findings suggest that SIRT2 participates in the last step of GABA production, while hydrogen peroxide (H2O2) is produced earlier in the process. They noted that inhibition of SIRT2 continued H2O2 production, indicating that neuronal degeneration might continue even though GABA production is reduced.

By identifying SIRT2 and ALDH1A1 as downstream targets, scientists can now selectively inhibit GABA production without affecting H2O2 levels. This breakthrough allows researchers to separate the effects of GABA and H2O2 and study their individual roles in neurodegeneration.

“This finding paves the way for more precise therapeutic strategies aimed at controlling astrocytic reactivity in Alzheimer’s disease,” said Director C Justin Lee. “We can now dissect the effects of GABA and H2O2 and study their individual roles in disease progression.” While SIRT2 may not be a direct drug target due to its limited effects on neurodegeneration, this research opens up new possibilities for treating AD.

Alzheimer's

Lecanemab Demonstrates Favorable Safety Profile in Real-World Setting

In a recent study, researchers found adverse events were rare and manageable among clinic patients with very mild or mild Alzheimer’s disease who received lecanemab infusions.

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The Food and Drug Administration’s (FDA) approval of lecanemab in 2023 marked a significant milestone in the treatment of Alzheimer’s disease. This novel therapy has been shown to modestly slow disease progression in clinical trials. However, concerns about side effects, such as brain swelling and bleeding, have led some patients and physicians to hesitate about using the medication.

Researchers at Washington University School of Medicine in St. Louis conducted a retrospective study to investigate the adverse events associated with lecanemab treatment in their clinic patients. The study, published in JAMA Neurology on May 12, focused on 234 patients with very mild or mild Alzheimer’s disease who received lecanemab infusions at the Memory Diagnostic Center.

The results of the study are reassuring. Only 1% of patients experienced severe side effects that required hospitalization. Patients in the earliest stage of Alzheimer’s, with very mild symptoms, had the lowest risk of complications. This information can help inform patients and clinicians as they discuss the treatment’s risks.

“This new class of medications for early symptomatic Alzheimer’s is the only approved treatment that influences disease progression,” said Barbara Joy Snider, MD, PhD, a professor of neurology and co-senior author on the study. “But fear surrounding the drug’s potential side effects can lead to treatment delays. Our study shows that WashU Medicine’s outpatient clinic has the infrastructure and expertise to safely administer and care for patients on lecanemab, including the few who may experience severe side effects, leading the way for more clinics to safely administer the drug to patients.”

Lecanemab is an antibody therapy that clears amyloid plaque proteins, extending independent living by 10 months, according to a recent study led by WashU Medicine researchers. The medication is recommended for people in the early stage of Alzheimer’s, with very mild or mild symptoms. In this study, only 1.8% of patients with very mild Alzheimer’s symptoms developed any adverse symptoms from treatment compared with 27% of patients with mild Alzheimer’s.

“Patients with the very mildest symptoms of Alzheimer’s will likely have the greatest benefit and the least risk of adverse events from treatment,” said Snider. “Hesitation and avoidance can lead patients to delay treatment, which in turn increases the risk of side effects. We hope the results help reframe the conversations between physicians and patients about the medication’s risks.”

The study found that most cases of amyloid-related imaging abnormalities (ARIA), a side effect associated with lecanemab, were asymptomatic and only discovered on sensitive brain scans used to monitor brain changes. Of the 11 patients who experienced symptoms from ARIA, the effects largely resolved within a few months, and no patients died.

“Most patients on lecanemab tolerate the drug well,” said Suzanne Schindler, MD, PhD, an associate professor of neurology and a co-senior author of the study. “This report may help patients and providers better understand the risks of treatment, which are lower in patients with very mild symptoms of Alzheimer’s.”

Overall, the study demonstrates that lecanemab can be safely administered and tolerated by most patients in a real-world setting, especially those with very mild symptoms of Alzheimer’s disease. This information can help alleviate concerns about side effects and encourage more patients to consider treatment with this novel therapy.

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Alzheimer's

The Key to Protein Quality: Unraveling the Role of P97/VCP Enzyme

In neurodegenerative diseases such as Alzheimer’s or Parkinson’s, proteins accumulate in the body’s cells, fold incorrectly and clump together to form larger aggregates. Normally, cells are able to remove these aggregates themselves. However, if a certain enzyme is blocked, this clean-up process no longer works. The new findings provide a better understanding of the molecular basis of these processes.

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The intricate dance of protein quality control within cells has been revealed by researchers led by biochemist Alexander Buchberger at Julius-Maximilians-Universität Würzburg (JMU). A recent study published in Nature Communications sheds light on the crucial role played by the ubiquitin-selective unfoldase p97/VCP enzyme in eliminating malformed proteins and aggresomes.

In cells, proteins are constantly being produced, assembled, transported, and broken down. This delicate balance is vital to prevent serious illnesses, as even small changes can have devastating consequences. To maintain this balance, cells have developed complex systems to control protein quality. One such system involves the formation of aggresomes – a type of cage that collects and isolates proteins prone to clumping.

While the formation of aggresomes has been extensively studied, their protein content and degradation pathways remained poorly characterized. The recent study changes this by revealing that the breakdown of aggresomes requires multiple players, with p97/VCP enzyme emerging as the most critical.

The researchers conducted experiments blocking p97/VCP enzyme and observed that aggresomes no longer disintegrated and were destroyed. This indicates that p97/VCP plays a pivotal role in breaking down aggresomes into smaller components. The findings have significant biomedical implications, particularly for understanding neurodegenerative diseases such as Alzheimer’s, Parkinson’s, and Huntington’s disease.

Mutations in the p97/VCP enzyme cause neuro-muscular degenerative diseases, including certain forms of dementia and ALS – amyotrophic lateral sclerosis. Moreover, disrupted degradation processes within cells could also contribute to Parkinson’s disease, which is characterized by Lewy bodies – roundish inclusions containing harmful protein deposits that disrupt nerve cell metabolism.

The research team concludes that their findings suggest mutations in the p97/VCP enzyme disrupt aggresome degradation, potentially contributing to Lewy body formation and neuro-muscular degenerative diseases. This study highlights the importance of understanding protein quality control mechanisms within cells and how disruptions in these processes can lead to devastating diseases.

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Alzheimer's

The Surprising Link Between Curiosity and Healthy Aging

Psychology literature has shown that curiosity tends to decline with age. Psychologists shows one type of curiosity can increase well into old age, contradicting prior research. Older adults who maintain curiosity and want to learn new things relevant to their interests may be able to offset or even prevent Alzheimer’s disease. Conversely, those who show muted curiosity and disinterest may be at risk for dementia.

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The secret to aging successfully may not be what you think. Instead of focusing on physical exercise or mental stimulation alone, research suggests that cultivating curiosity can play a significant role in maintaining cognitive health and even preventing Alzheimer’s disease. An international team of psychologists has found that older adults who maintain a curious mindset and seek out new knowledge relevant to their interests may be able to offset or prevent dementia.

This finding challenges prior research that suggested curiosity decreases with age. The study, published in the journal PLOS One, was led by UCLA psychologist Alan Castel and involved a large sample of participants between the ages of 20 and 84. The researchers aimed to tease apart two types of curiosity: trait curiosity (a general level of inquisitiveness) and state curiosity (a momentary feeling of curiosity experienced when engaging with specific topics).

To assess these forms of curiosity, the researchers asked participants to complete an online questionnaire and guess answers to hard trivia questions. Analysis showed that while trait curiosity did decline across the adult lifespan, state curiosity increased sharply after middle age and continued upward well into old age.

The study’s lead author, Mary Whatley, notes that this finding may be related to selectivity theory, which suggests that as people get older, they become more selective about what they want to learn. This aligns with research on lifelong learning, where many older adults engage in activities like taking classes or picking up hobbies.

Castel’s own work on memory has shown that people tend to quickly forget information that doesn’t engage their curiosity. Anecdotally, many older adults report that staying curious is crucial for maintaining cognitive health and preventing dementia.

This study was supported by the National Institutes of Health’s National Institute on Aging, the Leverhulme Trust, and the Alexander von Humboldt Foundation. The findings suggest that cultivating curiosity can be a key factor in healthy aging and may even help prevent or offset Alzheimer’s disease.

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