Understanding Dementia
As we age, every organ in the body changes in structure and function. Hair cells lose their pigment, the lens of the eye may get cloudy with cataracts. For nearly all of us, the brain becomes slower and less efficient. Those infamous “senior moments” are usually caused by this slow down. This normal process of aging, however, is very different from the group of illnesses called dementia that some of us develop in our later years.
Dementia is a general term for a group of brain diseases in which brain function is significantly declined. Key features of this decline include:
A significant change from prior cognitive abilities
It occurs slowly and progressively
It Is severe enough to interfere with usual activities and daily life
Affects more than one of the following four core mental abilities
Recent memory: the ability to learn and recall new information
Language: the ability to write or speak, or to understand written or spoken words
Visuospatial function: the ability to understand and use symbols, maps, etc., and the brain’s ability to translate visual signals into a correct impression of where objects are in space
Executive function: the ability to plan, reason, solve problems and focus on a task
These illnesses appear slowly over many years and can be difficult to detect and diagnose. For some individuals the changes are quite noticeable, while for others the changes are subtle and may be missed or confused with other conditions for years.
As more and more patients have been diagnosed with dementia, doctors have discovered that there is an important, POSSIBLY early stage of dementia called Mild Cognitive Impairment (MCI).
In MCI, a person has problems with mild memory lapses and/or difficulty with one of the other areas of cognition affected by dementia, such as executive function or language. These problems may or may not show up on tests of mental function, and are not serious enough to interfere with daily life. When symptoms do not disrupt daily activities, a person does not meet criteria for being diagnosed with dementia. Individuals with MCI have an increased risk of developing Alzheimer’s disease over the next few years, especially when their main problem involves memory. However, not everyone diagnosed with MCI progresses to Alzheimer’s or another kind of dementia.
Though we do not fully understand all the causes of dementia, there are several known illnesses that cause it or are commonly considered “types” of dementia.
Alzheimer’s disease
Alzheimer’s disease is the most common type of dementia, accounting for 60 to 80 percent of cases. The strongest risk factors include age and family history. Although symptoms can vary widely, the first problem many people with Alzheimer’s notice is forgetfulness severe enough to be noticeable to others and to affect their work, lifelong hobbies, or social life. Other symptoms include confusion, trouble with organizing and expressing thoughts, misplacing things, getting lost in familiar places, and changes in personality and behavior.
These symptoms result from damage to the brain’s nerve cells. It is not yet fully clear why the brain cells malfunction and die, but scientists believe two abnormal structures that appear in the brain called amyloid plaques and tau tangles are involved. These abnormal agents and the inflammation they induce are currently under active research scrutiny as the causative agents. No matter the cause, the disease gradually gets worse as more cells are damaged and destroyed. For the individual, increasing dysfunction leads to increasing dependency as the process first involves intellectually active parts of the brain and later parts that control physical function.
Vascular dementia (VD)
People who develop vascular dementia may have a history of heart attacks. High blood pressure or high cholesterol, diabetes or other risk factors for heart disease are often present as well.
Vascular dementia is the second most common type, after Alzheimer’s disease. It occurs when there is reduced circulation to the brain over prolonged periods. Circulation of blood is vital for delivery of energy in the form of oxygen and food to nerve cells. In some cases, clots block blood flow to parts of the brain, depriving nerve cells of food and oxygen. If it develops soon after a single major stroke blocks a large blood vessel, it is sometimes called “post-stroke dementia.” It can also occur when a series of very small strokes, or infarcts, clog tiny blood vessels. Individually, these strokes do not cause major symptoms, but over time their combined effect is damaging. This type used to be called “multi-infarct dementia.” Symptoms of vascular dementia can vary, depending on the brain regions involved. Unlike Alzheimer’s disease where short term memory loss is a common and prominent symptom, forgetfulness may or may not be a prominent symptom, depending on whether memory areas are affected. Other common symptoms include difficulty focusing attention and confusion. Decline may occur in “steps,” where there is a relatively sudden change in function over hours to days.
Mixed dementia
In mixed dementia, Alzheimer’s disease and vascular dementia occur at the same time. It is now known mixed dementia occurs more often than was previously realized and becomes increasingly common as people age. Autopsy studies show that the brains of up to 45 percent of people with dementia have signs of both Alzheimer’s and vascular disease. Decline may follow a pattern like either Alzheimer’s –slowly progressive -or vascular dementia—stepwise/decline and plateau progression- or a combination of the two.
Dementia with Lewy bodies (DLB)
Like Alzheimer’s disease, this illness is not completely understood. In DLB, abnormal deposits of a protein called alpha-synuclein form inside the brain’s nerve cells and ultimately disrupt function. These deposits are called “Lewy bodies” after the scientist who first described them. Lewy bodies have been found in several brain disorders, including dementia with Lewy bodies, Parkinson’s disease, and some cases of Alzheimer’s. Similar to Mixed Dementia, there is often a combination of symptoms of both Alzheimer’s disease and Parkinson’s disease seen in patients with DLB.
Symptoms of DLB include:
Memory problems, poor judgment, confusion, and other symptoms that can overlap with Alzheimer’s disease
Movement symptoms are also common, including stiffness, shuffling walk, shakiness, lack of facial expression, problems with balance and falls that can be seen in Parkinson’s disease.
Excessive daytime drowsiness
Visual hallucinations
Mental symptoms and level of alertness may get better or worse (fluctuate) during the day or from one day to another
Rapid eye movement (REM) sleep disorder. REM sleep is the stage where people usually dream. During normal REM sleep, body movement is blocked, and people do not “act out” their dreams. In REM sleep disorder, movements are not blocked, and people act out their dreams, sometimes vividly and violently.
Frontotemporal dementia (FTD)
FTD is a rare disorder chiefly affecting the front (Frontal lobe) and sides (Temporal lobe) of the brain. Because of the location of the illness, the first symptoms of this type of dementia are different from typical Alzheimer’s disease and involve changes in aspects of thinking that are controlled by the frontal and temporal lobes. These can include: Changes in personality, judgment, planning and social skills. Individuals may make rude or off-color remarks to family or strangers or make unwise decisions about finances or personal matters. They may show feelings that seem inappropriate or disconnected from the situation, such as indifference or excessive excitement. They may have an unusually strong urge to eat and gain weight as a result.
One way to distinguish FTD from other dementia is with brain imaging if atrophy in these two affected lobes occurs. This can be a particularly devastating and disturbing illness given the areas affected. It has been seen that FTD progresses more quickly than Alzheimer’s disease and tends to occur at a younger age.
Parkinson’s disease (PD)
Parkinson’s disease is another of the brain illnesses but has a distinct difference from other dementias. In PD the cells that are damaged and destroyed are chiefly in a brain area important in controlling movement. Symptoms are not intellectual at first rather they include: tremors and shakiness, muscle stiffness, difficulty with walking or “shuffling”, poor muscle control and balance, lack of facial expression, and impaired speech.
Two Interesting facts connect PD with dementia. First, it has been determined that the cell injury involves Lewy bodies. And, many individuals with PD develop dementia in later stages of the disease. This happens up to years later and is referred to as Parkinson’s-related Dementia.
Normal pressure hydrocephalus (NPH)
Normal pressure hydrocephalus is another rare disorder where fluid surrounding the brain and spinal cord is unable to drain normally. As the fluid-filled ventricles expand, they compress and damage nearby tissue. “Normal pressure” refers to the fact that despite the fluid increase and pressure effects, the spinal fluid pressure often, although not always, falls within the normal range on a spinal tap.
A trio of symptoms define NPH: (1) difficulty walking, (2) loss of bladder control and (3) mental decline, usually involving an overall slowing in understanding and reacting to information. While the response is delayed, the intellect of the patient with NPH appears to be intact when the answer finally comes.
In some cases and especially when caught early, NPH can be treated by surgically inserting a long thin tube called a shunt to drain fluid from the brain to the abdomen. When shunting surgery is successful, it tends to help more with walking and bladder control than with mental decline.
Creutzfeldt-Jakob disease (CJD)
Creutzfeldt-Jakob disease (pronounced CROYZ-felt YAH-cob) is a rare, rapidly fatal disorder known to be caused by a specific genetic variation. CJD is rapidly progressive and usually fatal within a year. It usually affects individuals older than 60. CJD is one of the prion (PREE-awn) diseases. These disorders occur when prion protein begins to fold into an abnormal three-dimensional shape leading to increasing damage and destruction of brain cells. Symptoms can include impairment in memory, thinking and reasoning, or changes in personality and behavior including depression or agitation. Problems with movement may be present from the beginning or appear shortly after the cognitive symptoms start.
Huntington’s disease (HD)
HD is a fatal brain disorder caused by inherited changes in a single gene. These changes lead to destruction of nerve cells in certain brain regions. Anyone with a parent with Huntington’s has a 50 percent chance of inheriting the gene, and everyone who inherits it will eventually develop the disorder. In about 1 to 3 percent of cases, no history of the disease can be found in other family members. The age when symptoms develop and the rate of progression varies.
Symptoms of Huntington’s disease include twitches, spasms, and other involuntary movements; problems with balance and coordination; personality changes; and trouble with memory, concentration or making decisions.
Wernicke-Korsakoff syndrome
Wernicke-Korsakoff syndrome is a metabolic disorder caused by a deficiency of thiamine (vitamin B-1). Thiamine helps brain cells use sugar to produce the energy it needs. Without sufficient thiamine, cell death occurs. The most common cause of thiamine deficiency is alcoholism.
There are two distinct phases of this disorder: Wernicke encephalopathy is the acute phase and Korsakoff psychosis is the long-lasting, chronic stage. If the condition is caught early and drinking stops, treatment with high-dose thiamine may reverse any damage. Often, however, the damage is permanent and progressive.
Symptoms of Wernicke-Korsakoff syndrome include:
Confusion, permanent gaps in memory and problems with learning new information
Individuals may have a tendency to make up information they can’t remember
Unsteadiness, weakness, and lack of coordination
Drawn from materials at www.alz.org
Please talk with your own healthcare provider before using any of this information.
