Dear Doctor: Could you explain panic attacks? I never knew what people were talking about until a few months ago, while sitting at the computer. I felt as if I had stopped breathing; I thought I was dying. I ended up in the ER, but no problems were found. This has happened several times since, and I want my life back.

Dear Reader: Panic attacks are truly a scary experience, especially if you've never had them before. Many of the symptoms are similar to those of a heart attack, causing people to seek immediate attention in an urgent care department or emergency room. The symptoms, which develop suddenly, can include chest pain, heart palpitations, sweating, nausea, shortness of breath, lightheadedness and, for many, the feeling that they're going to die.

Such attacks are surprisingly common. One-third of people have at least one panic attack during their lifetime. Those who experience recurrent panic attacks not related to generalized anxiety, depression, obsessive-compulsive disorder or post-traumatic stress disorder have what is termed panic disorder. People with panic disorder have a persistent worry about having another panic attack and the consequences of future attacks. That leads them to avoid situations that may induce panic attacks, which, in turn, leads to a profound alteration in quality of life. Panic disorder affects nearly 3 percent of the population, ages 15 to 54.

People with panic disorder often report an increase in stressful life events over the past year and, even more often, within the past month. Genetic factors also play a role. A person who has a first-degree family member with panic disorder is three times more likely to develop the disorder compared to people without such a tie. Further, an identical twin is five times more likely to have anxiety and panic if his or her twin has the disorder.

The symptoms of panic attacks are essentially a normal "fight or flight" response to a very stressful situation, such as an encounter with a lion, tiger or grizzly bear. However, panic attacks occur without the lion, tiger or bear. Some experts hypothesize that panic attacks are abnormal central nervous system responses to even the most mundane stimuli. Such responses arise in the brain's limbic system, which normally processes sensory information into emotional responses, behavior and memory. The hyperresponsiveness to sensory inputs -- and even the inputs from one's own thinking -- leads to a poor regulation of the autonomic nervous system, which controls heart rate, the contraction of the heart, blood pressure, the gastrointestinal system and sweating. MRI studies have confirmed alterations in the limbic system in people with panic disorder.

Panic attacks can also be precipitated by stimulants such as caffeine, cocaine and amphetamine as well as withdrawal from alcohol, opiates or benzodiazepines like Valium, Ativan and Xanax. Although patients sometimes use benzodiazepines to stop a panic attack, these medications can induce rebound panic when the drug is out of the system, making them a poor treatment option.

Cognitive behavioral therapy shows the greatest sustained benefit in stopping panic attacks, because it can alter the underlying brain responses. Selective serotonin reuptake inhibitor medications also can help.

In summary, starting therapy and possibly medication will be the first steps in getting your life back.

(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: A lot of my friends are talking about pickles these days because they're a way to get probiotics into your diet. But I read that pickled foods are associated with higher rates of cancer. Are pickles good or bad for you? I'm confused.

Dear Reader: While it's true that researchers have identified the consumption of pickled vegetables as a potential risk factor in certain gastric cancers, it doesn't necessarily mean you have to ditch those delicious dill spears that came with your sandwich. In the big picture, the data suggest a link between pickles and some cancers, but when you drill down into the details, it turns out that additional factors appear to be at play.

Let's start with pickles themselves. Virtually every culture in the world has a tradition of pickling. Methods vary, but most use some combination of salt, liquid and sometimes oil to induce and support fermentation, which preserves food for use beyond its growing season.

In the United States, cucumbers and cabbage account for the majority of pickled vegetables. At just 4 pounds per person per year, they're treated as a condiment. However, in many other parts of the world, including China, Japan, Korea and Turkey, a wide range of fermented vegetables (as well as fruit, soy products and sometimes meat) are a dietary mainstay, eaten daily for nine to 12 months of the year.

The idea of a pickle-cancer link arose when scientists began to look at cancer registries established in China in the 1960s. As researchers crunched the numbers, they found a high rate of gastric cancer in regions where pickled foods were eaten daily throughout the year. Since then, though, other groups of researchers have analyzed a wide range of these studies. They found that differing methodologies, as well additional lifestyle factors, made the direct link between pickles and cancer more tenuous.

In some cases, the populations being studied also ate high-fat diets and a lot of barbecued meat, both of which have a link to increased cancer risk. In other study groups, smoking was widespread and thus also implicated in potential disease. And, finally, there were the pickles themselves.

For example, a traditional way of pickling vegetables in parts of China involves packing them in salted water, sometimes seawater, for a period of weeks or months. During this time, fermentation occurs. However, the process also produces yeasts and fungi, some of which have the potential to produce compounds that are carcinogenic. A combination of the pickling method and the volume of vegetables consumed could be a factor in the higher gastric cancer rates.

In the U.S., by contrast, most commercially produced pickles are made without fermentation, in a process that uses vinegar and pasteurization. Although this eliminates the risk posed by those carcinogenic compounds, it also means these pickles won't be a source of probiotics. In addition, pickles are high in sodium, with a single dill pickle packing a hefty 50 percent of a day's supply of sodium.

Bottom line, with what we know now: Whether it's fermented or commercial pickles that you're eating, moderation is the key.

(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: My husband and I have been reading about a possible connection between aluminum and Alzheimer's disease. Some reports even discourage the use of aluminum foil for cooking. Is there a connection between aluminum and Alzheimer's?

Dear Reader: Your worries center around the most-abundant metal and the third-most abundant element, one that by mass makes up 8 percent of the Earth's crust. Plants and animals have evolved in an environment in which aluminum is common. In fact, aluminum is even present in the human brain. This most fundamental of organs contains, on average, 1.02 micrograms of aluminum per gram of brain tissue. Further, brain levels of aluminum increase with age, causing researchers to take a look at how that happens -- and what might be the result.

The human body absorbs aluminum from compounds in water, food, aluminum-based utensils, deodorants and drugs. But at toxic levels, aluminum can damage neurons in the brain as well as DNA within neurons. The aluminum ion can affect normal cellular reactions in the brain, cause brain inflammation and lead to neurofibrillary tangles and amyloid deposits that are the hallmark of Alzheimer's disease. In fact, aluminum chloride in combination with the sugar D-galactose injected in rats and mice induces many of the brain changes and behavioral changes seen in Alzheimer's disease.

In one important study, researchers studied the postmortem brains of 12 people with familial Alzheimer's disease in England. They found elevated aluminum content in all but one of the brain samples. The researchers also found aluminum concentrated near neurofibrillary tangles and amyloid deposits, which have been linked to Alzheimer's. They couldn't conclude that aluminum was the cause of the dementia; it may be that degenerative brain diseases concentrate and retain aluminum within the brain. Still, a connection seems clear.

The findings are alarming. Aluminum is more ubiquitous today than ever before. Aluminum hydroxide, aluminum sulfate and aluminum chloride are used in drinking water treatment and waste water management, and we use aluminum foil and aluminum in our food preparation and storage. Considering such exposure, it's important to ask questions about the potential impact.

A 15-year study in France assessed the aluminum levels in drinking water and the rate of Alzheimer's disease in multiple areas of southern France. The concentration of aluminum in the water varied from 0.001 to 0.514 mg/liter depending on location. Of the 1,677 people over the age of 65 who completed the study, 461 were diagnosed with dementia. Those whose aluminum intake was more than 0.1 mg per day had 2.26 times the risk of dementia compared with those whose intake was less than 0.1 mg per day.

All of that said, neither I nor medical science overall can provide a hard and fast answer to your question about the risk of aluminum exposure. It is heartening, however, to know that water boards measure the amount of aluminum in drinking water at a time when the correlation between human exposure to high levels of aluminum and dementia is still largely unknown.

(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.)