Dear Doctor: My 81-year-old father is scheduled for a heart procedure, and I'm actually less worried about the surgery itself than the effects of the anesthesia. I've read that it can lead to memory loss in the elderly. Is there any way to help him?

Dear Reader: The condition you're referring to is known as postoperative cognitive dysfunction, sometimes shortened to POCD. It's loosely defined as impairment to the mental functions of an individual following surgery performed under general anesthesia. And while your question zeroes in on anesthesia as the cause of those cognitive side effects, the jury is still out on that. Some researchers point to the rigors of surgery itself as well as the body's resulting inflammation response as contributing factors to the condition.

Symptoms of POCD include impaired memory, difficulty learning and retaining new information, a shortened attention span, problems carrying out more than one task at once and a decline in the ability to concentrate. These can develop over time following surgery and may last a few weeks, a few months or in some cases become permanent. While the condition can occur in any surgical patient, it's most often seen in elderly individuals.

One of the challenges to diagnosing POCD is that unless the patient has undergone pre-operative cognitive testing, assessing his or her post-operative condition relies on observational and anecdotal evidence. In cases where the syndrome is pronounced, a reliable diagnosis can be made. But in more subtle cases, where those around the patient feel he or she has "lost a step" following surgery, citing POCD as the direct cause becomes more difficult. With that in mind, we'd like to share with you the following recommendations from the American Society of Anesthesiologists:

-- Before surgery, undergo a cognitive test that can be used as a baseline against which to compare similar post-surgical testing, if needed.

-- Make sure your surgeon is familiar with all medications and supplements you're taking in the weeks and days before surgery, and any that you plan to take following the procedure. This includes medications to address pain, sleep and anxiety.

-- Patients who wear glasses or use hearing aids find it easier to re-enter the post-surgical world when their sight and hearing are at optimal levels. Assign someone the task of making them available to you as soon as possible following surgery.

-- Arrange for a caregiver, who can notice and report any troubling symptoms, to visit with you regularly as you recover.

-- Anchoring yourself in the present as soon as possible after surgery is important. Request a room with a window, so you have visual cues regarding the passage of time, as well as your physical location.

-- In that same vein, photos of family, friends and pets, familiar possessions, and a clock and a calendar, all can help you readjust.

With an aging populace, many of whom will go on to require surgery, recognizing and preventing POCD is rapidly becoming a public health issue. A wide range of researchers are now focused on it. As new findings emerge, we will share the latest information.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: What can you tell me about an allergy to nickel? I recently had skin testing after experiencing itchy skin, a rash and fluid-filled blisters that several doctors thought might be mosquito-related. Instead, I tested positive for nickel allergy. Even the nickel in my bra clasps and earrings make me break out. Do I need to avoid certain foods? Is this problem hereditary?

Dear Reader: Nickel allergies are quite common. Although nickel is only about .009 percent of the Earth's crust, the metal and its compounds are found in a large number of common objects, such as coins, earrings, rings, watches, bras, belt buckles, mobile phones, medical devices and dental implants. And, as you referenced, nickel is found in small amounts in many foods. Unfortunately, nickel is the most common metal allergy in humans, affecting more than 10 percent of people in the United States. Women are five times more likely to have an allergic reaction to nickel than are men, largely because of their exposure to nickel-containing jewelry.

For people with nickel allergies, nickel ions provoke an immune response within the skin. After multiple exposures, the immune system can overreact when exposed to the metal. This type of reaction is called a delayed hypersensitivity reaction and it occurs 48 to 72 hours after the exposure.

There does appear to be some genetic predisposition to nickel allergies, but really, allergies to nickel are more related to exposure than to heredity. People who frequently handle coins, such as cashiers and toll road collectors, have greater amounts of allergic reactions on the hand than does the general population.

Again, the problem with nickel is how commonly the metal is used in clothing and in jewelry. That can be attributed to its strength and its resistance to oxidation. That said, Denmark has regulated nickel in its consumer goods and thus has the lowest rates of nickel allergy among industrialized countries. Other European countries have taken similar action; the United States has not.

Obviously, the best course of action is to avoid nickel in clothing and jewelry. One way to detect nickel is through a rapid testing kit, or dimethylglyoxime test. Here's how it works: You apply the test solution to a cotton swab, rub the swab on the metal of a product you're thinking of buying and -- if the product contains any nickel -- the swab turns pink.

Titanium, platinum, sterling silver, some types of stainless steel and gold that is at least 18 karats should be free from nickel. As for earrings with nickel (a common metal in such jewelry), you can create a barrier between it and your skin by coating the metal that touches your ear with nail polish or specific products marketed for nickel allergies. For clothing with nickel-containing buttons, you can apply an iron-on cloth over the metal portion or simply use duct tape. Finally, you can use barrier creams on the skin that comes in contact with nickel from jewelry.

Case reports suggest that skin reactions to nickel can diminish with a reduction of nickel in the diet, but your reaction appears to be related specifically to skin contact. So, for you, if you can't avoid nickel, I recommend using a barrier against it.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: It seems like every time I turn on the news someone's freaking out about ticks and mosquitoes. Haven't they always been around? What's with the alarm bells all of a sudden?

Dear Reader: The reason you're hearing so much about ticks and mosquitoes these days is because of a worrisome spike in the number of people becoming infected with the range of diseases these creatures cause. (We can't say "insects" because, while mosquitoes do fall into that category, ticks don't. They're actually arachnids -- like mites, spiders and their larger cousin, the scorpion.) According to a report released by the federal Centers for Disease Control and Prevention in May, the incidence of disease spread by ticks and mosquitoes has more than tripled between 2004 and 2016.

In just 13 years, the number of tick- and mosquito-borne illnesses in the United States has ballooned from 27,388 reported cases in 2004 to 96,075 reported cases in 2016. Even more concerning is the fact that more than half of that increase occurred between 2015 and 2016. And the key word here is "reported." Not every tick- or mosquito-borne illness is identified or gets reported, so the number of people made ill by a tick or mosquito bite is quite likely higher. (The CDC's report also covers fleas, with a total of 89 reported cases of plague over the 13 years of the report.)

Lyme disease accounted for 82 percent of the increase in tick-borne illness, according to the report. A closer reading of a breakout of the data reveals some troubling trends. For example, babesiosis, a malaria-like illness carried by deer ticks, went from zero cases in 2010 to more than 1,900 reported cases in 2016. Anaplasmosis, also caused by a bacterium carried by the deer tick, jumped more than 650 percent, from 875 cases in 2004 to 5,750 cases in 2016. If left untreated, the disease can cause internal bleeding, difficulty breathing, neurological problems and kidney failure.

When it comes to mosquitoes, the report offers both good and bad news. Cases of Zika have gone from zero in 2015 to 41,680 the following year. Virtually all were reported in Puerto Rico, American Samoa and the U.S. Virgin Islands. West Nile virus, meanwhile, which hit a high of 5,674 cases in 2012, dropped by half by 2016. In addition, the CDC reports that nine new germs that are spread by ticks and mosquitoes have been identified since 2004. Scientists say the rise in disease rates, as well as the widening of their geographic scope, is due in part to the warming climate, which expands the pests' habitats. Global trade and travel also play a role.

Our aim here is not to alarm, but to stress the importance of vigilance in protecting yourself and your family. Bottom line: Create a barrier between yourself and the potential threats. That means appropriate clothing to cover you when spending time outdoors, bug repellent for a chemical shield, and regular visual checks of your skin, scalp and clothing. And don't forget about the pets -- a range of excellent meds are available to keep your furry companions tick- and flea-free as well.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)