Dear Doctor: Our older sister has become a hoarder. The halls in her house are filling up with junk, and you can’t even get into her kitchen anymore. My brother and I worry she’s not safe. Why does a hoarding disorder happen? How do we help her?

Dear Reader: Hoarding disorder is a recognized diagnosis in the DSM-5 -- the Diagnostic and Statistical Manual of Mental Disorders, which is the authoritative guide to the diagnosis of mental disorders. People who are hoarders struggle to discard or part with possessions that others see as useless. They acquire and store vast amounts of stuff, which compromises the function and safety of their homes. When asked why, they will express the belief that the objects have either monetary or sentimental value, or that they may be useful in the future. While other people see accumulations of old newspapers, magazines, plastic bags, tools, broken furniture or household items as worthless junk, these things exert a powerful mental and emotional pull on the person who amassed them.

You and your brother are correct that a hoarding disorder can pose a real risk to health and safety. There’s the danger of trips or falls. The inability to use a bathroom, bedroom or kitchen as intended interferes with both physical well-being and hygiene. Piles of stuff often block ventilation or heating ducts and obstruct windows and doors, which create safety and fire hazards. Cramped and chaotic conditions encourage dust, mold or mildew, as well as insect and rodent infestations. All of this can lead to structural damage to the home, and even pose a danger to neighbors.

There are psychological harms as well. People who hoard often live with a profound sense of shame. And as you are experiencing, hoarding affects the family as well. It can cause relationships to become strained or impaired, and for many people who hoard, the disorder leads to social isolation.

It’s important to understand that hoarding has nothing to do with being messy, lazy or indecisive. Instead, it’s a mental health disorder. People who hoard struggle to decide when to throw something away. When faced with discarding or giving away their possessions, they experience great distress and anxiety. Researchers have linked hoarding to obsessive-compulsive disorder, or OCD, and to depression and anxiety disorders. Scans of hoarders asked to divide mail into ”keep” and “discard” piles have shown spikes of activity in the emotional centers of the brain.

When it comes to helping someone with a hoarding disorder, persuasion, logic or arguments don’t work. Neither does force. Instead, experts recommend beginning by clearly stating your concerns for the person’s health and safety. Most hoarders know that something is wrong, and that their living situations are both peculiar and dangerous. Then, provide avenues of assistance. Some people find help with cognitive behavioral therapy, in which the individual is guided to identify and understand their thinking patterns, and then focus on gradual change. Individual therapy with a specialist in hoarding disorders can be helpful, as can group therapy, which allows the person to see they are not alone. You can find more information and resources at the Anxiety and Depression Association of America’s website, at adaa.org.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I’ve heard that there’s finally a test for Alzheimer’s disease, and that it has to do with your eyes. What is it, and how does it work?

Dear Reader: Although researchers continue their search for a single and definitive diagnostic test for Alzheimer’s disease, they haven’t reached that goal at this time. However, they continue to make advances in the field, including recent studies that suggest impaired eye movement may be a predictive symptom in some cases. We don’t yet have a cure for Alzheimer’s disease, but early intervention has been linked to better outcomes for patients, including an improved quality of life. That makes any developments that aid in diagnosis important.

As most of you probably know, Alzheimer’s is a progressive disease. Physical changes that occur within the brain gradually result in cognitive impairment and dementia. Although Alzheimer’s disease is most often seen in older adults, it is not considered a normal part of aging. Symptoms include a decline in memory, thinking, speech, judgment, concentration and the ability to carry out tasks. The disease also results in changes to mood and personality. Other types of dementia and cognitive impairment share many of the same symptoms, which makes early diagnosis more challenging. A diagnosis of Alzheimer’s involves a range of screening processes, including a neurological exam, tests to assess cognition and mental status, genetic testing and brain imaging scans. For some patients in the early stages of the disease, watchful waiting is a necessary -- and sometimes frustrating -- part of the process.

The study you’re asking about looks into impaired eye movement as a diagnostic tool in at-risk patients. Participants with two different types of cognitive impairment were assigned visual tasks on a computer screen. For example, they were asked to look at the left side of the screen whenever a flashing icon appears on the right side. A device that can measure 500 eye movements per second then analyzed how well each person completed the task. The researchers found that the visual behavior of each group was unique enough that they could differentiate between the two types of dementia just by the results of the tests. Even more promising was the fact that the eye movement pattern in one type of dementia, where people struggled to look at the correct side of the screen, was similar to those with an Alzheimer’s diagnosis.

The takeaway here is that eye tracking shows potential for predicting whether someone with mild cognitive impairment is likely to progress to Alzheimer’s disease. That means instead of waiting for advancing symptoms, more patients could begin treatment earlier than is now possible.

Without a cure for Alzheimer’s, patients rely on therapies developed to prolong and increase independence and improve quality of life. These include memory training, mental stimulation, social integration and physical exercise programs. Cognitive therapies, such as puzzles, simple number and arithmetic problems and memory exercises have also been shown to have a benefit. These are all most successful before Alzheimer’s disease has progressed too far, which makes early diagnosis all the more important.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: Our dad was diagnosed with lung cancer and will be getting chemo and radiation. I’m not really sure how they work, or why he has to have both. Should we get a second opinion?

Dear Reader: We use the word “cancer” to refer to a group of diseases in which abnormal cells within the body begin to divide uncontrollably. They are able to evade the body’s natural defenses, and, over time, they can spread throughout the body. The goal of cancer treatment is to prevent these rogue cells from dividing. This is achieved either by killing the cancer cells outright, or disrupting their DNA, and thus their ability to divide. Radiation and chemotherapy are two of the most common cancer treatments. Although each works to stop the progress of the disease, they act in different ways.

Chemotherapy is a systemic treatment. That means that the specialized drugs used in chemotherapy are administered via the bloodstream so that they can reach and act upon cells throughout the body. More than 100 different chemotherapy medications fall into five major categories. Each of these drug categories behave in a different way, but all share the same objective. That is, to disrupt the life cycle of cells within the body that divide rapidly, which includes cancer cells.

Chemotherapy drugs are quite powerful. Because they circulate to all parts of the body, they act on all of the rapidly dividing cells in the body, including those that are not cancer. This includes hair roots, which is why hair loss occurs in many cancer patients undergoing chemo. Other common side effects include nausea, vomiting, fatigue, anemia and infection.

Radiation therapy, by contrast, is a localized treatment. It targets a specific part of the body where cancer cells are found. The powerful energy -- delivered via X-rays, gamma rays, electron beams or protons -- destroys cancer cells and damages their DNA as well. This prevents the rogue cells from dividing and growing, and thus stops their spread.

Some radiation treatments involve ingesting, injecting or implanting a radioactive substance, which either locates or binds to cancer cells. Although the effect on noncancerous cells isn’t as severe in radiation therapy as it is in chemotherapy, healthy cells do get damaged. This results in side effects such as skin problems at the delivery site and fatigue.

Depending on the type of cancer and how far it has spread, it’s not unusual for several treatments to be used together. This includes chemotherapy and radiation therapy, as well as surgery, immunotherapy, hormone therapy and targeted drug therapies.

In certain types of lung cancer, studies have found that using chemotherapy along with radiation therapy can improve survival rates. While radiation is effective at targeting solid tumors, chemotherapy can act upon cancer cells throughout the body, including those that haven’t yet been identified.

Lung cancer treatment is a rapidly advancing field. For that reason, it’s often helpful for patients to have their case and treatment plan reviewed by a physician or medical team that specializes in the disease. To avoid unexpected costs, check with your insurer for guidance on which doctors and facilities are covered by your plan.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)