The Small Guide to Alzheimer's Disease. Gary Small
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Название: The Small Guide to Alzheimer's Disease
Автор: Gary Small
Издательство: Ingram
Жанр: Медицина
isbn: 9781630061289
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Common Symptoms of Normal Brain 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.
Memory decline is the main cognitive complaint that most people focus on as they get older, but deterioration in language skills, reasoning, spatial orientation, and concentration can disrupt lives as well. Sometimes patients with MCI experience greater difficulties with decision-making than with memory. Their judgment becomes impaired, and they may have trouble finding their way around familiar settings. Depression, anxiety, irritability, and other mood changes may emerge, and both cognitive and mood alterations only get worse as MCI progresses to dementia. Personality traits may become altered or exaggerated. For instance, a man who was mildly distrustful of strangers all his life may become paranoid that all strangers are out to get him.
Although normal aging does gradually worsen with time, it remains relatively stable for most people over the years. Despite this stability, some of the physiological changes associated with an aging brain can be observed using brain scanning technologies.
These categories were created to help doctors and scientists communicate and readily describe the degree of cognitive impairment each patient is experiencing. However, the progression of brain aging is slow and subtle in most cases, and the transitions from normal aging to mild cognitive impairment and dementia are not sudden but insidious. The conditions are defined in large part by the patient’s ability to function, and that ability will vary from person to person. An executive who has a personal assistant compensating for her cognitive slips may be able to function relatively independently much longer than someone without a personal assistant.
Some people have what’s been termed cognitive reserve. Their high intelligence allows them to compensate much longer as their brain aging progresses. I’ve seen several people with cognitive reserve who seem to function quite well—as if they have normal aging—even though their brain scans reveal Alzheimer’s disease that appears to be moderate in severity.
Depression and Anxiety Worsen Memory
A 78-year-old retired schoolteacher was brought to the emergency room because of a depressed mood, memory loss, confusion, insomnia, weakness, and agitation. As is typical in emergency room settings, the doctors drew her blood to perform some laboratory tests to search for medical causes of an altered mental state. They also got a brain scan of her head to make sure there wasn’t a tumor or brain hemorrhage that could be causing her mental symptoms.
The laboratory tests came back normal, and the brain scan didn’t pinpoint any tumors, strokes, or blood clots. The medical team still had several unanswered questions: What is this patient suffering from? Is it Alzheimer’s disease? Is it depression? Could it be a combination of the two, or possibly something else entirely? The patient was admitted to the hospital, and over the next week it became clear that she had mild Alzheimer’s dementia that was worsened by a depression.
Mood and cognitive symptoms frequently overlap in older adults. Patients with mild cognitive impairment or dementia often experience feelings of anxiety and sadness. Particularly early on in the course of cognitive decline, when patients are aware of their cognitive deficits, they typically experience an emotional reaction to those losses.
Patients with mild memory complaints often tell me how worried they are about their symptoms. Research shows that if patients worry about their symptoms, their memory performance scores will be worse compared to those who do not. Anxiety and other mood changes are distracting and make it difficult to focus attention, which is essential for learning new information and retrieving it later—the basic mental skills needed for effective memory function.
Changes in the brain associated with chronic dementias like Alzheimer’s disease can cause imbalances in the brain messengers (i.e., neurotransmitters) that control mood. Once those neurotransmitters decline, the likelihood of mood symptoms increases. Our UCLA group performed PET scans on older patients with major depression, which is a form of depression that is severe enough to require medical intervention. These patients generally experience a persistently depressed mood and loss of pleasure or interest in life as well as disturbed sleep, feelings of guilt, and suicidal thoughts.
In our study, we found that the amyloid plaques and tau tangles that are typical of Alzheimer’s disease were also present in the brains of these older patients with major depression. This raises the possibility that symptoms of depression may be a manifestation of Alzheimer’s disease in some older patients, especially early in the course of brain neurodegeneration. Other studies have supported the idea that depression can be a risk factor for developing dementia. These issues are critically important because an accurate diagnosis of the underlying condition or conditions is essential for determining the most effective treatment strategy for the symptoms.
Investigators at St. Louis University СКАЧАТЬ