Skin and Hair Archive

On call

Q. Is there any difference between sunstroke and heatstroke and are there certain signs and symptoms I should look for?

A. These two terms refer to the same condition. Heatstroke (or sunstroke) happens when the body can no longer maintain a temperature of under 105° F when exposed to hot weather. People almost always have warning symptoms before heatstroke, yet sometimes they do not pay attention, or are not able to take action.

The first accurate medical discussion of psoriasis dates back to 1801, but the disease itself is much older. In fact, its very name is borrowed from an ancient Greek word meaning an itchy or scaly condition. About 7 million Americans are plagued by this itching and scaling, and many of them have serious complications involving other organs. Although psoriasis is classified as a dermatologic disease, it doesn't start in the skin, and its damage may be more than skin deep.

Beneath it all

At a basic level, psoriasis is a disorder of the immune system. White blood cells called T-helper lymphocytes become overactive, producing excess amounts of cytokines, such as tumor necrosis factor, interleukin-2, and interferon-gamma. In turn, these chemicals trigger inflammation in the skin and other organs. In the skin, the inflammation produces three characteristic findings: widened blood vessels, accumulation of white blood cells, and abnormally rapid multiplication of keratinocytes, the main cells in the outer layer of the skin. In healthy skin, keratinocytes take about a month to divide, mature, migrate to the skin surface, and slough off to make way for younger cells. But in psoriasis, the entire process is speeded up to as little as three to five days. The result is thickened, red skin that sheds silvery scales of keratinocytes that have matured before their time (see Figure 1).

Q. I'm 63, and I've begun to notice a decline in the quality of my fingernails. They have numerous up-and-down ridges, and at the tips, they're always splitting. I've heard you can tell a lot about a person's health from the condition of her nails. What does my split nails say about mine?

A. Some changes in nails can be a sign of an underlying health problem, but the lengthwise nail ridging you describe is usually not one. It's simply a common sign of normal aging. The growth of fingernails and toenails slows as we get older, and their appearance may change. Some nails become yellowed or dull and brittle, and some or all may develop tiny longitudinal ridges. Fingernails tend to become thinner and more fragile, while toenails usually become thicker and harder.

Research we're watching

If your hair has been thinning, an infusion of your body's own plasma may help grow it back, according to the American Academy of Dermatology.

A number of recent studies show that platelet-rich plasma (PRP) therapy is successfully regrowing lost hair. This includes a 2018 study in the International Journal of Women's Dermatology that found the technique was beneficial in treating androgenetic alopecia, a type of genetically and hormonally driven hair loss that affects as many as 35% of women by age 60.

There are lots of dubious claims and mysterious ingredients, but yes, by trapping water, moisturizing can help with dry skin.

Dry skin by itself isn't a medical worry, although serious cases can result in cracks and fissures that invite infection and inflammation. The real issue is discomfort — dry skin can be sore, tender to the touch, and often itchy (although not all itchy skin is dry). There's also the red, rough, scaly appearance lamented in many advertisements for moisturizers.

This is one problem that hasn't suffered from lack of attention: there are dozens of creams and lotions for dry skin. They are sold as moisturizers, which is more of a marketing term than a medical or scientific one. Indeed, routine skin care is a realm where there's little science to be found. Well-controlled studies of ingredients are few and far between. Companies keep information about ingredients proprietary and are careful to limit claims for what the products do to stay within FDA rules.

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Q. Does the acne drug, isotretinoin (Accutane), cause depression and suicide, or are psychiatric risks from the Accutane side effects exaggerated?

In the journals

Zinc oxide (ZO) is one of the most effective ingredients in sunscreen, but previous studies have suggested it could potentially damage skin cells. Now, a small study in the February 2019 Journal of Investigative Dermatology has found that ZO nanoparticles don't penetrate the skin or damage skin on a cellular level even with repeated applications.

ZO is one of 17 active sunscreen ingredients approved by the FDA. ZO offers broad-spectrum protection and shields against both UVB rays, which cause sunburn, and UVA rays, which penetrate more deeply and are more likely to damage cell DNA and increase the risk of skin cancer.

Microneedling was once viewed with skepticism, but it can be an effective procedure to improve the skin.

If the idea of poking yourself in the face with tiny needles in hopes of improving your skin sounds a little bizarre to you, you're not alone. For years, the medical establishment looked at the practice, known as microneedling, with a leery side-eye.

"I didn't take it seriously until relatively recently," says Dr. Kenneth Arndt, medical editor of the Harvard Special Health Report Skin Care and Repair and a founding editorial board member of the Harvard Health Letter.