The Small Guide to Alzheimer's Disease - Gary Small

Скачать книгу

well as rigidity and other motor symptoms typical of Parkinson’s disease. Frontotemporal dementia primarily affects the frontal and temporal lobes of the brain, causing difficulties in thinking, language, and personality but fewer symptoms of memory loss than in Alzheimer’s. In addition to these progressive neurodegenerative diseases, there are some cases where a reversible cause of the dementia is discovered. Anything from drug toxicity to urinary tract infections to depression can lead to cognitive impairments that disrupt a patient’s daily functioning.

       • Memory loss

       • Difficulties in reasoning

       • Disorientation, getting lost

       • Language difficulties such as word-finding

       • Misplacing things

       • Mood or personality changes

       • Showing less interest or initiative

       • Trouble completing familiar tasks like cooking or cleaning

      Completely reversible dementias are relatively rare, but I’ve certainly seen them during the course of my practice. In fact, one of the first patients I saw while training as a geriatric psychiatrist was admitted to the hospital with a working diagnosis of Alzheimer’s dementia. During my assessment, I discovered that he had been taking 10 milligrams of Valium (diazepam) every evening for several years. I gradually tapered down his Valium dose, and within a few weeks I had “cured” his dementia.

      Although most dementias are chronic and progressive, sometimes a treatable medical cause is uncovered, which reverses some or occasionally all of the symptoms. There are hundreds of different causes of dementia. Below are some of the more common ones and examples.

Possible Cause Examples
Medical illness Pneumonia, heart failure, cardiac arrhythmia, thyroid abnormalities, anemia, cancer, liver disease, lung disease, kidney failure, infections, metabolic disturbances, vitamin B12 or folate deficiency, autoimmune disease
Medications Sedatives, antidepressants, over-the-counter sleep medicines, antihistamines, steroids, pain medicines
Neurodegenerative disorders Lewy bodies (abnormal brain protein deposits), frontotemporal dementia, Parkinson’s disease, normal pressure hydrocephalus (excess brain fluid), vascular disease, Down syndrome
Psychiatric disorders Depression, anxiety
Other conditions Head injury, toxic exposures

      Because there are so many medical conditions that can cause a dementia, it is important for families and patients to see their doctor if they are concerned about a memory issue. A simple blood test, brain scan, or physical examination can uncover a treatable illness. Early treatment of such illnesses usually yields the best outcome.

      Many times, tests reveal that a combination of both a medical illness and progressive neurodegeneration is causing the patient’s dementia. However, even in those cases, correcting treatable illnesses like anemias, thyroid abnormalities, or medication side effects can improve the patient’s cognitive symptoms to some extent.

      Helen, who forgot she left the bathtub filling, and most of her 50-something friends were all noticing memory slips. Usually they joked about it and accepted their forgetfulness as normal for a certain age. But Helen had moments when her concerns were greater, and her symptoms seemed worse when she was under stress or didn’t get enough sleep.

      With each passing year, an individual’s risk for normal memory slips increases. By age 45, memory performance for the average person is significantly worse than their performance was in their mid-20s. And those objective memory declines correlate with what’s known as subjective memory—an individual’s self-awareness of their cognitive changes.

      What causes these lapses is not entirely clear, but years of scientific inquiry have detailed brain changes that correlate with the symptoms. For example, the amyloid plaques and tau tangles, which Professor Alzheimer described in his original case of the disease, begin to accumulate in the brain decades before people are actually at risk for developing dementia symptoms. Neurotransmitters or brain messengers that permit brain cells to communicate begin to malfunction, and the brain’s circulatory system is less effective in transporting oxygen and nutrients from the heart to the brain cells. An aging brain also undergoes wear and tear from head trauma injury, oxidative stress, and heightened inflammation associated with aging.

       • Forgetting names and faces

       • Not remembering where you put things

       • Failing to recall an appointment or plan

       • Forgetting a word or name you should know that is on the tip of your tongue

      By middle age, most people start noticing and joking about mild memory slips. But if these cognitive issues progress over the years, then mild cognitive impairment (MCI) may emerge, a transition stage between normal age-related forgetfulness and actual dementia. Most people over 50 have already experienced occasional memory slips, such as blanking on someone’s name or the title of a recently read book. If these problems worsen and become more frequent and severe, that’s when MCI kicks in.

      People experiencing MCI struggle more with their memory. It may take them longer to get out of the house because they’re repeatedly searching for misplaced keys or glasses or checking that doors are locked and windows are shut. They may ask the same question more than once during a conversation. Despite these changes, however, these individuals are still able to function independently. They are able to compensate for their increasingly challenging mental abilities. However, when they can no longer compensate for these changes, they may progress to the next stage of brain aging, dementia, or a cognitive deficit that makes them dependent on others for their daily functioning.

      Ten percent of people with MCI will develop dementia within a year. This means that in five years, 50 percent of people with MCI will get dementia. Using a brain positron emission tomography (PET) scanning method I developed with my research team at UCLA, it is possible to see into the living brain and watch how it progresses through these stages. As a patient’s cognitive symptoms escalate, scans can provide physical evidence of brain shrinkage, buildup of abnormal proteins, decline in cellular function, and other alterations. Using functional MRI scanning, we can observe how neural circuits start to work harder to overcome the encroaching brain disease and compensate for the neurons that have become dysfunctional by recruiting healthy ones to pitch in. Unfortunately, at some point this compensation mechanism breaks down and dementia takes over.

      The figure illustrates the slow and steady memory decline that affects nearly everyone if they live long enough. Although age is the biggest risk factor for memory loss, everyone’s brain ages at a different rate. In fact, some 90-year-olds have a sharper memory than some 60-year-olds. The transitions between normal aging, MCI, and dementia are very gradual, and what distinguishes dementia from the earlier stages is that patients can no longer live on their own without help.

Скачать книгу