The Many Faces of Dementia
Dementia—changes in memory, thinking and behavior that interfere with daily activities—is among the most feared of health problems associated with aging. Alzheimer’s disease (AD) is the most common cause of dementia, affecting up to 5 million Americans. However, as many as 50 percent of cases of dementia are associated with other conditions that are less well known and may sometimes be mistaken for AD. As with AD, these conditions result in damage to or changes in the brain leading to memory decline. They are also characterized by at least one other symptom, such as declines in language ability, thinking, or decision-making.
Because some dementias may be treatable, getting prompt assessment of any changes in memory and thinking is extremely important, according to Scott McGinnis, MD, a staff neurologist at MGH, and instructor in neurology at Harvard Medical School.
“Symptoms of dementia may be caused by a number of potentially remediable factors, such as nutritional deficiency, reactions to medications, dehydration, thyroid problems, low blood sugar, depression, infections, or brain tumors,” Dr. McGinnis says. “Autoimmune and inflammatory diseases may also lead to symptoms that may be reversible or improvable.”
A disorder called normal pressure hydrocephalus (NPH)—which is caused by a buildup of fluid in the brain—can cause problems such as difficulties with gait, attention, problem-solving and memory, Dr. McGinnis explains. If caught at an early stage, NPH can be successfully treated by implanting a tube to drain excess fluid from the brain into the abdomen.
“Even if the dementia cannot be reversed, early intervention may allow for the use of drugs that can slow its progression and help improve symptoms such as depression or restlessness,” Dr. McGinnis says. “Being under a doctor’s care also helps ensure that you learn about new research developments and can benefit from new treatments when they become available.”
WHAT YOU CAN DO
McGinnis suggests seeking professional assessment for cognitive changes that involve the following symptoms:
- Changes in mental ability that are more severe than those of your peers
- Significant changes in memory and thinking that appear to be lasting
- Signs of mental confusion, such as asking the same question over and over, completely forgetting a recent event, or getting lost in familiar places
- Problems speaking or understanding language
- Behavioral changes, such as behaving in socially inappropriate ways, losing the ability to empathize with others, or displaying extreme levels of apathy.
Ocular clues
One new research development offers hope for speedier diagnosis of a type of irreversible dementia called frontotemporal dementia (FTD), which involves the degeneration of cells in the frontal and temporal lobes of the brain. FTD is usually first diagnosed in people in their 50s and 60s, and may have a genetic component. It is distinguished by the slow onset of behavioral symptoms such as loss of judgment and inhibitions, impulsivity, or withdrawal. Symptoms also include cognitive problems and impairment of memory and language ability.
Researchers recently discovered that very early signs of FTD can be detected by close examination of the retina of the eye, which is composed of nerve cells with direct connections to the brain and reflects changes that might affect brain cells. According to a report published September 2014 in The Journal of Experimental Medicine, the scientists compared the retinas of individuals with a genetic mutation that is known to result in FTD to those of comparable individuals without the genetic mutation. Compared to healthy participants, those with FTD showed signs of a thinning of the retina and a reduction of electrical activity in retinal cells. The retinal changes were visible even before the onset of cognitive symptoms—in effect, establishing retinal degeneration as one of the earliest signs of familial FTD.
“This research is important because it is an example of molecular diagnosis—the detection of changes that are visible under the microscope before symptoms appear on brain scans or through identification of dementia symptoms,” says Dr. McGinnis. “We need these markers to improve our ability to distinguish one neurodegenerative disease from another. And not least, these kinds of research advances offer hope that one day dementias can be accurately diagnosed and effectively treated long before they cause irreparable damage to brain cells.”
Common non-AD dementias
Most common non-AD dementias affect areas in the brain responsible for cognitive processes or the blood vessels that supply these brain regions with oxygen and nutrients. They may occur alone or in combination with AD or other types of dementia. People who suffer from these irreversible dementias require long-term support. In addition to FTD, the most common non-Alzheimer’s dementias include:
▶ Vascular dementia (VAD). VAD is caused by cerebrovascular diseases that restrict the supply of blood to the brain, such as strokes or diseases of the small blood vessels in the brain. Its symptoms include difficulties with memory, problem-solving, or concentration. VAD sometimes comes on abruptly, and may develop in a stepwise fashion (a period of decline followed by a stable period, followed by further decline). Treatments such as lifestyle changes, medication, and the control of risk factors for vascular disease (e.g., hypertension, high cholesterol, diabetes, and smoking) may slow the disease progression.
▶ Mixed dementia. People with mixed dementia simultaneously experience brain problems that are characteristic of more than one type of dementia. In one study involving autopsies of AD patients, 54 percent were found to have at least one other type of dementia. Symptoms of mixed dementia vary according to the types of dementia and the brain regions affected. It is not often diagnosed during the patient’s lifetime.
▶ Parkinson’s disease (PD). A movement disorder characterized by stiffness, tremors, slowed movements, and problems with balance and coordination, PD often leads to dementia in its later stages. Cognitive changes have been linked to the gradual accumulation within the brain of clumps of proteins called alpha-synuclein. Although PD is a progressive disease, worsening of symptoms can be slowed with medications and other therapies.
▶ Dementia with Lewy bodies (DLB). This often-misdiagnosed dementia may affect as many as 1.3 million Americans, yet it is often confused with AD or PD. DLB involves the accumulation of clumps of alpha-synuclein (called Lewy bodies) in the cerebral cortex, the area of the brain responsible for memory, thinking, attention, and language. Symptoms include movement disorders as in PD, but also difficulties with attention, memory, language, and decision-making, as well as visual, hallucinations, sleep abnormalities, and depression. Treatment focuses on managing symptoms through medication.
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