Types of Dementia on the Physician Assistant Exam
Dementia essentially refers to brain degeneration, and it’s irreversible. The Physician Assistant Exam (PANCE) will expect you to know about it because it’s a significant problem, especially in the older population. Alzheimer’s is on the rise, and with the epidemic of obesity, diabetes, and hypertension, you’ll see more and more cases of vascular dementia.
Different types of dementia can affect different areas of the brain. For example, in a clinical scenario where an older person is behaving like an infant (for example, sucking his thumb and displaying infant-like reflexes), think of a dementia affecting the frontal lobe. When the frontal lobe is affected, the person loses all inhibitions. An example of a frontal lobe type of dementia is Pick’s disease.
How to distinguish dementia from delirium and pseudodementia
On the PANCE, expect to see a question in which a person, usually an older person, is admitted with a change in mental status. You’ll have to determine whether you’re dealing with delirium or dementia. The answer depends on a couple of factors:
Time frame: Although dementia is a process that occurs over a long period of time (months to years), delirium usually occurs over the course of a few days. For example, a urinary tract infection, pneumonia, or volume depletion can cause a change in mental status acutely over the period of a few days, if not faster, and cause delirium. Medications can cause delirium big time.
Types of change: Delirium can be associated with changes in thinking and perception. The affected person can be hyperactive or completely lethargic. Sometimes the behavior patterns can change in a single day. The key concerning the management of delirium is in looking for an underlying cause.
Dementia, on the other hand, is a serious loss of mental faculties, which can include cognition, memory, attention, perception, language, problem-solving, and interpersonal skills.
Don’t confuse dementia with pseudodementia, which commonly afflicts older individuals. In pseudodementia, the person appears to be demented but typically is just extremely depressed. The difference is in how the person answers your questions. In the person with pseudodementia, the cognition and perception are generally intact. The demented person answers questions strangely and may not even pay attention to what you’re asking.
Alzheimer’s dementia (commonly called Alzheimer’s disease) is by far the most common form of dementia. It likely accounts for more than half of all the cases of dementia. The typical scenario is an older person who initially experiences worsening problems with memory, especially short-term memory.
Over time, the affected person begins to have other problems, including confusion, labile mood (mood swings), and trouble with speaking. The person can become isolated and unable over time to perform activities of daily living (ADL). This condition can be extremely difficult for caregivers and for family members, who often are the caregivers.
The symptoms usually present in individuals in their mid-60s; however, Alzheimer’s dementia can be early onset as well.
Here are four key points about Alzheimer’s dementia:
If you were to look under the microscope, you would see that beta amyloid plaques and neurofibrillary tangles are present in the brain of someone with Alzheimer’s. It’s postulated that the plaques and the tangles inhibit and destroy the function of the nerve cells somehow. This destruction may be the cause of the dementia symptoms.
The diagnosis is made from having a high clinical suspicion of the dementia plus exclusion of other, reversible causes of dementia. Imaging studies such as an MRI and a PET scan can help in the diagnosis.
Medications may prevent worsening of the disease. Examples are donepezil (Aricept), which is an anticholinesterase inhibitor, and memantine (Namenda), which is a glutamate receptor antagonist.
In the later stages of Alzheimer’s dementia, regular caregiving becomes impossible for family members and significant others because the person requires 24-hour care. The person often needs to be placed in a supervised care facility.
Vascular dementia, or multi-infarct dementia, is the most common type of dementia after Alzheimer’s. Although Alzheimer’s dementia is more common in women, vascular dementia is more common in men.
Risk factors for vascular dementia include hypertension, diabetes, and long-standing vascular disease. Atherosclerosis, inflammation, small vessel disease, and infarctions all likely play a role in the development of vascular dementia. Atrial fibrillation can also be a risk factor, usually due to multiple embolic infarcts. All these processes are damaging to the blood vessels and affect the circulation in the brain. These blood vessels have been damaged over time.
Here are a couple of key points about vascular dementia:
Loss of abilities can occur in steps as the small vessels in the brain (the lacunae) are affected (a lacunar infarct). Therefore, this type of dementia is considered a stepwise dementia.
Treatment of risk factors can delay vascular dementia. This means controlling blood pressure, regulating blood glucose levels, decreasing factors of inflammation, and watching cholesterol levels.
Many medical conditions, especially B12 and folic acid deficiencies, can cause dementia if left untreated for a long period of time. Syphilis can also be a cause of dementia. Myxedema, which results from long-standing uncontrolled hypothyroidism, can also present with a dementia-like picture.
Note that in a small percentage of people, vascular dementia and Alzheimer’s dementia can co-exist. This can be very difficult to diagnose and to manage.
Lewy body dementia
Lewy body dementia, which combines many of the features of Alzheimer’s dementia with Parkinson’s disease, is the third most common type of dementia. It’s caused by Lewy bodies, which you find in the neurons of people affected by this syndrome.
The main symptoms of this type of dementia include significant changes in the level of alertness throughout the day. Hallucinations, especially visual hallucinations, can also be present. Lewy body dementia has a motor component as well; motor symptoms can resemble Parkinson’s disease.
The treatment of Lewy body dementia involves treatments utilized for both Alzheimer’s dementia and Parkinson’s disease. Medications such as donepezil (Aricept), which is an anticholinesterase inhibitor, and a glutamate receptor antagonist such as memantine (Namenda) are used for some of the dementia symptoms of this condition. Anti-Parkinson’s medications are used to help treat the motor symptoms.