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Does waist size predict dementia risk?

The first large-scale cohort study of its kind looked at the link between waist circumference in later life and the risk of dementia in a population of older Asian adults. Physicians, healthcare professionals, and medical researchers tend to use body mass index (BMI) to determine if a person's weight is too high, too low, or "normal." Despite its widespread use, BMI has its flaws — and one flaw is the fact that it does not discern between fat (adipose tissue) and muscle content (lean tissue). For this reason, some scientists have suggested that waist-to-height ratio or waist circumference measurements may be more accurate indicators of a person's healthy weight. When it comes to older age, however, is there any link between waist circumference and cognitive health? One 2019 study that Medical News Today reported on, for example, found a link between carrying excess weight around the stomach and experiencing brain atrophy, or brain shrinkage. Another large study, this time from 2018, found correlations between belly fat and poorer cognitive function. However, some of these studies looked at BMI or waist-to-hip ratio. Others have found that a higher BMI raises the risk of dementia, whereas other studies have found the opposite. Where does the truth lie? Is there a connection between fat and brain health in older age? If so, what is the best weight measurement that indicates the risk of neurological conditions such as dementia? New research led by corresponding author Hye Jin Yoo, an associate professor at Korea University Guro Hospital in Seoul, set out to investigate. The findings now appear in the journal Obesity. Dr. Dan Bessesen, of the University of Colorado School of Medicine in Aurora, was not involved in the research but comments on its significance. He says, "This study does not let us know why there is this discrepancy but may point to the different roles of subcutaneous fat and visceral fat in the development of dementia, with subcutaneous fat being protective and visceral fat having harmful effects." Visceral fat is that which surrounds internal organs, and it has links with various conditions. Subcutaneous fat is visible beneath the skin. This study was limited to an Asian population, so further studies will be necessary to replicate the findings in larger populations. (Credits: www.medicalnewstoday.com)

Hair follicles can be a site of origin for melanoma

New research argues that melanoma can start not only in the skin, but also inside hair follicles. When they become cancerous, the cells then leave the follicles and move into the skin's outermost layer, or epidermis. The scientists demonstrated this effect in a new mouse model of human melanoma and confirmed it in samples of human tissue. In a recent Nature Communications study paper, the team describes melanoma starting in immature, pigment producing cells in hair follicles, then moving into the epidermis. Melanoma is an aggressive skin cancer that is very difficult to treat in its advanced stages. For this reason, while only 1% of people Trusted Source who develop skin cancer have invasive melanoma, it is responsible for most deaths due to skin cancer. The cancer begins in melanocytes, which are the cells that make the pigment that gives color to the hair, skin, and eyes. This pigment is called melanin. The new study focuses on melanocyte stem cells, which are cells that have not yet fully differentiated into their final mature state. In another set of experiments, the researchers tested what happened when they silenced cell environment signals in the hair follicle one by one. These showed that, even when melanocyte stem cells had taken on cancerous properties, they did not travel and divide to form melanomas unless they received two particular signals from their environment. These signals are called Wnt and endothelin, and they normally promote proliferation of pigment cells and growth of the hair shaft in the follicles. (Credits: www.medicalnewstoday.com)