Dear Doctor: Could you please explain Creutzfeldt-Jakob disease? Some people call it "mad cow disease," which gives it a stigma. I lost my twin brother to this disease, and it's left our family shattered.

Dear Reader: I am truly sorry for your loss. My family also lost a loved one to this devastating disease. We could only watch helplessly as it quickly took away all vestiges of the person we once knew.

For those unfamiliar with it, I'll explain: Creutzfeldt-Jakob disease (CJD) is the most common prion disease in humans. (The others are predominantly found outside the United States.) Prions are infectious, but they're not viruses or bacteria; they're proteins. They appear to be created from normal proteins found on cell membranes. The normal proteins may help inhibit cell death, but in prion diseases, they reconfigure. This initial change is believed to be related to an external agent, possibly a virus, chemical or drug, in 85 to 95 percent of patients and to a genetic cause in 5 to 15 percent of patients.

The term "mad cow disease" is actually a misnomer, because the majority of cases are not related to prion transmission between cows and humans. It can happen, of course, such as the 1990s outbreaks in the United Kingdom that led to the term. But these animal-to-human transmissions of prions, termed Variant Creutzfeldt-Jakob disease, are very rare. Even more rare is human-to-human transmission via transplanted livers, cornea and brain tissue.

Regardless of the cause, exposure to abnormal prions leads to a cascading effect -- the creation of more abnormal prions that disrupt nerve cells' function and lead to their death. This destruction causes holes within the brain tissue, leaving it with a spongelike appearance.

The disease initially interferes with concentration, memory and judgment and leads to episodes of sleep throughout the day. In terms of mood, a person may at first seem neglectful, apathetic and depressed, quickly giving way to unrelenting mental deterioration. Patients eventually develop dementia and can lose the ability to control muscle movements, resulting in twitching or jerking contractions of the muscles. Progression is slower for people younger than 50, but regardless, death usually occurs within one year of symptom onset, with an average time to death of six months.

The only positive in this scenario is that CJD is rare, affecting one in a million people per year.

Many other diseases can initially appear similar to CJD, which is diagnosed with an assessment of symptoms, aided by electroencephalograms (EEGs) and MRIs of the brain. Protein markers in spinal fluid can also help. But the best way to definitively diagnose CJD is to look at brain tissue, most often done at autopsy.

As you already know, there is no good treatment for CJD. Flupirtine, a drug available in Europe, can protect cognitive function to some degree, but does not alter survival. Quinacrine and chlorpromazine can inhibit the formation of abnormal prions but have not shown an ability to stop the disease.

That isn't to say research has stopped, only that it hasn't made huge strides. Everyone who has watched anyone suffer with CJD is hoping science can ultimately find a way to treat this terrible disease. In the meantime, we can all help educate others as to the real nature, and name, of Creutzfeldt-Jakob disease.

(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: How important is it to keep track of a child's blood pressure? I read that the American Academy of Pediatrics just updated its guidelines for screening and managing high blood pressure in kids. Is this really a problem that I need to worry about?

Dear Reader: We're so glad you brought up this very important topic. Blood pressure is a diagnostic tool that's as important in children as it is in adults. However, because blood pressure readings in children are evaluated by a different set of metrics than those of adults, the subject has often been confusing.

By now, the significance of high blood pressure, or hypertension, is well known to most of us. It's not a condition that you can readily feel, but when left untreated it can cause significant damage to your body. By the time symptoms appear, you can be dealing with a host of problems, including damage to your heart, kidneys, eyes, bones and cognitive function.

High blood pressure in children can be a predictor of the condition later in life. It can cause certain types of damage to the structures and blood vessels of a child's heart. And it can be a symptom of other serious underlying conditions, including heart or kidney problems. Between 2.2 to 3.5 percent of children have high blood pressure, according to the new guidelines. The number jumps up to 24 percent among children who are obese or overweight. Children who were born prematurely and those with sleep-disordered breathing are also at risk of high blood pressure.

That's why establishing a baseline blood pressure reading beginning as early as the age of 3 is important. After that, a child's blood pressure should be measured during annual physical exams, and the trajectory of those readings over time should be noted and used as a diagnostic tool.

Thanks to the new blood pressure guidelines, released in August 2017 by the American Academy of Pediatrics, this should be much more easily accomplished. Unlike in adults, whose blood pressure readings fall into uniform parameters, readings in children must be interpreted based on gender, age and height. It's no surprise that, with so many variables to deal with, repeated studies show that up to 75 percent of children with high blood pressure have gone undiagnosed.

Before, health care professionals had to delve into multiple pages of charts to assemble the numbers and come up with a reading. The updated guidelines have simplified this pile of data into a single table. It's easy to use and easy for everyone, including parents, to understand.

For a child to be diagnosed with high blood pressure requires three separate readings that fall above the established guidelines. A single high reading, while not a diagnosis, does indicate the need for subsequent evaluations to rule out hypertension.

If your pediatrician or family physician doesn't routinely check your children's blood pressure, don't be afraid to ask. With one-third of adults in the United States now diagnosed with hypertension, it's clear that it's never too soon to get ahead of this serious condition.

(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: I am a senior citizen on Medicare. I don't have a "regular" doctor, but rather, I go to a clinic when I have a problem. What is covered in the annual Medicare physical? What should I, as a patient, know and do?

Dear Reader: Let's face it -- health insurance can be complicated and confusing, and Medicare is no different. We hope we can offer a bit of clarity regarding Medicare's annual physical exams, the details of which often leave our own senior patients with plenty of questions.

In the 12 months after you enroll in Medicare Part B, you're eligible for something known as a "preventive care" visit. During this appointment, you'll tell your doctor your personal medical history as well as your family history. She or he will record your height, weight and blood pressure, and will calculate your BMI, or body mass index. You'll get a vision test, and you'll be evaluated for risk of depression and any other potential safety issues.

Certain screening tests and vaccinations may be ordered at this time. Because details vary depending on each specific case, be sure to ask your doctor whether additional costs will be incurred. You may have to pay coinsurance, and the Medicare Part B deductible may apply.

During this initial visit, you'll also have a chance to discuss advanced health directives, sometimes known as a living will. You will receive a written plan that details a future schedule of screenings, vaccines and any other preventive services your medical history has indicated may be necessary.

Each subsequent year, Medicare entitles you to an annual physical evaluation that is less comprehensive than what we think of as a full physical. Known as a yearly wellness exam, it focuses on what a physician can see, hear and feel during an exam, such as heart rate, blood pressure, weight, BMI, heart and lung sounds and visible symptoms. However, the wellness exam does not include blood tests like complete blood count, kidney, liver and thyroid function, diabetes and cholesterol screenings, or a check of vitamin D levels, which we include in annual physical exams in our practices. These can be ordered, but depending on the test, there can be additional costs.

To get the most out of any physical exam, we recommend that patients bring the following:

-- Complete medical records, including immunization records, results of recent screening tests and information on any surgeries.

-- A list of all medications and supplements you are currently taking, including dosage, history of use and any side effects you may have experienced.

-- Comprehensive medical family history, including diseases like cancer, asthma, diabetes, memory disorders or dementia.

This last part is important because if your doctor determines that you are at particular risk of a certain disease or condition, you may be eligible for additional screenings and more frequent screenings. However, this typically requires a referral.

Lastly, we would encourage you to find and build a relationship with a primary care physician. This will give you a medical "home base," a doctor who knows you and your medical needs, as well as a partner in your ongoing care and an advocate for your best quality of life.

(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.)