When studying Alzheimer's disease, researchers have long been interested in what happens inside the brain, particularly the buildup of amyloid-beta plaques and tau protein tangles. But a new study indicates that an important part of the problem may start far from the brain, specifically in the bone marrow, where immune system cells are formed.
Researchers found that Alzheimer's disease disrupts the process of producing a type of immune cell in the bone marrow, which limits the ability of these cells to reach the brain and help confront the pathological changes associated with the disease. Experiments on mice also showed that interfering with this mechanism led to restoring the production of these cells and improving some aspects of the disease, according to the Independent newspaper.
For decades, research into Alzheimer's disease has focused on the role of misfolded proteins in the brain, including amyloid-beta plaques and tau tangles. However, some of the damage associated with the disease may arise in places far from the brain, specifically in the spongy tissue of the bone marrow, which is home to stem cells in the body. These stem cells play a major role in the formation of specialized immune cells, and also contribute to the repair of damaged tissues.
Previous studies have indicated that certain immune cells originating in the bone marrow act as reinforcements for stable immune cells in the brain, and help them confront the pathological changes associated with Alzheimer's disease. Previous research in mice has also shown that brain-resident immune cells, when depleted and no longer able to efficiently clear amyloid plaques, can benefit from the arrival of bone marrow-derived immune cells, which may help reduce inflammation and slow cognitive decline.
However, exactly what these immune cells are, and the mechanism by which they travel to the brain, have not been completely clear. The researchers wrote in the study published in the journal “Nature Neuroscience” that the factors that limit its spontaneous migration to the brain affected by the disease are still unclear. In the new study, scientists found that monocytes, a type of white blood cell, suffer from a dysfunction associated with Alzheimer's disease. “In this study, we discovered that monocyte development is impaired in both animal models (mice) and human patients,” the researchers wrote.
In experiments on mice, researchers found that Alzheimer's disease disrupts the immune system's alarm signal, which allows the bone marrow to send reinforcements of monocytes to the brain. The results indicate that this defect is not related to the brain alone, but rather extends to the process of forming immune cells itself within the bone marrow. In healthy mice, scientists found that a large portion of stem cells present in the bone marrow retain their ability to renew the immune system in the long term. But mice with Alzheimer's disease lost this ability. The study showed that stem cells in the bone marrow of mice with Alzheimer's matured and transformed into specialized cells very early, and a clear defect appeared in the process responsible for generating monocytes.
The findings were not limited to animal models; Researchers indicated that a similar phenomenon had been observed in humans with Alzheimer's disease. The researchers found that the defect in monocyte development in mice was similar to that seen in human patients, reinforcing the importance of findings regarding the role of the bone marrow and peripheral immune system in the disease. In another step, scientists found that restoring the production of monocytes in the bone marrow, using targeted therapy, led to “alleviating the pathological changes associated with the disease.” Researchers believe that the intrinsic ability of stem cells to regenerate may be depleted early in people with Alzheimer's disease, which appears in the form of signs of accelerated aging in the blood system.
A recent study showed that taking vitamin D supplements in elderly people who already have sufficient levels of it may be associated with a faster decline in some cognitive abilities, but the researchers stressed that the results do not prove that the supplements are the direct cause, according to what was reported by the “Very Well Health” health website. The study, published in the journal BMJ Open, included 5,065 older adults over a period of 6 years. They underwent tests of cognitive abilities and reported their use of vitamin D supplements. About 40 percent of them were taking these supplements regularly.
The researchers found that supplement use among people who get adequate amounts of vitamin D from food and sun exposure was associated with worse performance in memory, attention, and information processing speed. But neurologist Augusto Miravalli, who was not involved in the study, warned against interpreting the results as evidence that vitamin D harms the brain. The study did not specify the doses of supplements taken by the participants, and its observational nature does not allow for proof of a causal relationship. It is also possible that there is what is known as “reverse causality,” meaning that some people who are already more vulnerable to cognitive decline may have taken supplements.
The results are consistent with previous studies that did not find a clear benefit from high doses in people who do not suffer from vitamin D deficiency. Data from a large study showed that taking 2,000 IU daily of this vitamin did not slow memory loss in most adults with normal levels. A Finnish trial in 2025 also concluded that taking 1,600 or 3,200 international units daily did not affect the risk of dementia in those with sufficient levels of the vitamin.
Most adults need about 600 to 800 IU of vitamin D daily. People with proven deficiency may need higher doses determined by their doctor. The report warned against taking doses exceeding 10,000 international units per day without medical supervision, as excessive levels may lead to calcium accumulation in the blood and other health problems. Researchers point out that current evidence does not support taking vitamin D in high doses with the aim of preventing Alzheimer's or cognitive decline in people who have sufficient levels of this vitamin.
Bleach (chlorine) is an effective cleaning and sterilizing material, but at the same time it is a strong substance that may cause damage to the skin, eyes, and respiratory system. It may also cause damage to some surfaces and fabrics if used incorrectly. Therefore, it is important to know the cases in which it can be used, and the precautions that should be followed to avoid its risks, according to WebMed.
Bleach is a very strong substance; Therefore, it is preferable to use it when needed, such as whitening clothes or cleaning traces of bodily fluids, such as blood, vomit, or waste. It is also an effective way to sterilize frequently touched surfaces, such as door handles, table tops, and light switches. Always be sure to dilute bleach with water according to the recommended proportions, and do not use it in a concentration higher than necessary.
Avoid mixing bleach with ammonia; Because this mixing leads to the formation of a toxic gas known as chloramine, which may damage the tissues of the eyes, throat, nose, and lungs, and may also cause breathing problems. Do not pour bleach directly onto clothing, and do not use more than the recommended amount; This may damage the fabrics. Bleach is an effective way to remove stains, but it is not suitable for use with all types of fabrics. It is not suitable for spandex, wool, silk or leather. Therefore, always make sure to read the label attached to the clothes to know the correct washing instructions and ensure that bleach can be used on them.
Bleach may damage the screen's protective coating, which is designed to resist fingerprints. Using alcohol-based wipes or a sterilizing substance may be acceptable, but it is recommended to check the manufacturer's instructions for your phone to ensure the appropriate materials for cleaning it. Whatever material you use for cleaning, be careful not to get any moisture into the phone's openings.
Bleach (chlorine) can cause skin burns in high concentrations, and its fumes may cause irritation to the eyes and lungs. Therefore, it is recommended to wear protective glasses, a mask, and gloves, in addition to covering the feet and wearing long-sleeved clothes and pants, while making sure to work in a well-ventilated place. Remember that bleach may leave stains on clothes; So avoid wearing any clothes that you love or are dear to you while using it.
Chlorine gas is released when bleach (chlorine) is mixed with acids, such as vinegar or drain cleaners. Inhaling large quantities of this gas is dangerous. It may cause coughing or wheezing, and may also lead to a burning sensation in the eyes, nose, and throat. Therefore, do not mix bleach with vinegar or any other cleaners or substances unless you are sure it is safe to mix them.
Bleach is corrosive and can corrode or damage metal surfaces. Therefore, avoid using it on copper, stainless steel, aluminum, or other metals. Also, do not use bleach to remove rust, especially rust on fabric; Because using it may make the stain permanent and fixed.
Bleach cannot effectively penetrate dust and dirt; This is partly because a thick layer of dirt can protect germs. So, start by cleaning the surface with soap and water to remove dirt first, then cover the entire surface with the bleach solution so that it looks visibly wet, and allow it to air dry. It's okay to use a mixture of bleach and water to clean cutlery or some surfaces, such as kitchen countertops, according to the appropriate instructions for use. But do not wash fruits and vegetables with bleach; It is enough to wash and scrub it well under running water.
