The following discussion is for general informational purposes only and is not meant to provide the reader with specific medical advice. Please consult with your personal physician, or with a neurologist, for specific advice, guidance and information regarding your particular circumstances.
Dementia is a general term used to describe memory impairment accompanied by problems with social and occupational functioning. The cognitive impairments caused by dementia are not a normal part of aging.
Many types of dementia have been identified, but the three most common entities are Alzheimer's disease (AD), Frontotemporal dementia (FTD) and vascular dementia (VD). AD was first described in 1907 by a German neuro-psychiatrist, Alois Alzheimer. Individuals with this disease generally experience progressive memory loss, disorientation and language problems. FTD was first described in 1892 by Arnold Pick, but interest in this disease lagged until the 1990's. FTD generally presents with changes in behavior, language problems and/or difficulties with decision making. In contrast to AD, individuals with FTD do not have pronounced problems with memory until later in the disease. VD occurs when a person experiences strokes that affect key portions of the memory pathway or has multiple strokes that affect their ability to process information. The characteristics of VD vary depending on the location of the vascular events. About 4 million Americans are estimated to have Alzheimer's disease. Age is the major risk factor for Alzheimer's disease. Five percent of persons over the age of 65 have AD, while almost 50% of persons age 85 and older suffer from AD. FTD accounts for 5-7% of diagnosed dementias. Individuals with FTD tend to present in their 50's, which is earlier than people with AD. VD can present at any time during an individuals lifetime, but generally occurs later in life than FTD.
The genetics of AD and FTD are not completely understood. A variation on chromosome 19, called APOE-e4, appears to be a risk factor for Alzheimer's disease. This gene variation is present in about 15% of the general population, but occurs in 50% of those with late-onset Alzheimer's disease. Presence of APOE-e4 is three times more common in AD patients than in people without this gene. Presence of the gene may mean an increased susceptibility is possible, not a definite probability of getting Alzheimer's. In general, AD, FTD and VD are not inherited, but some familial cases have been reported.
The course of AD and FTD varies tremendously, but they are always progressive. VD tends to be a more static disease unless an individual has recurrent strokes.
Early symptoms of Alzheimer's disease include short term memory loss and disorientation, generally presenting as becoming lost in familiar areas. As the disease progresses, these symptoms increase and word finding problems, especially pauses in conversations and forgetting common words, are present. Some individuals also lose insight into their condition and are unable to understand that they have cognitive problems. Depression, agitation and paranoia may also be present. Eventually, patients forget how to perform simple tasks of every day life and they are unable to comb their hair, get dressed, or feed themselves. They may also lose the ability to recognize faces and objects. 20-30 percent develop symptoms such as slow movement and trembling. Seizures can occur in 10-20 percent of patients often late in the disease.
The presentation of FTD varies depending on the part of the brain first affected. Marked changes in behavior or personality are common problems, but some individuals first present with severe language problems or difficulties making decisions. Memory is generally not affected early in this disease. As FTD progresses, people tend to develop problems similar to AD including memory problems and disorientation.
VD may present with any of the symptoms seen in AD or FTD. Generally, vascular dementia is not progressive, unless a person continues to have strokes or they have another disease, like AD, also present.
There is no single test to diagnose Alzheimer's disease, frontotemporal dementia or vascular dementia. They are often diagnosed by ruling-out many other potential causes of the symptoms. Illnesses like depression, hypothyroidism, vitamin B12 deficiency, hydrocephalus, cerebral vasculitis, neurosyphilis, stroke, ischemia, and some medications as well as alcohol abuse can cause problems with memory and behavior which can be mistaken for AD, FTD or VD.
To obtain a complete and accurate diagnosis, it is important to have a complete physical exam, health history, neurological and mental status exams and laboratory analysis of blood and urine. Your physician may order additional tests such as brain computerized tomography (CAT) scan, electroencephalography or brain magnetic resonance imaging (MRI). Neuropsychological testing is also very helpful in characterizing patterns of cognitive problems and can help monitor cognitive function over time. Positron emission tomography (PET) scan can also be used to help establish diagnoses in unusual cases.
There is currently no cure for any of the dementias described above. Treatments which are currently available help to stabilize cognitive problems, but they cannot restore memory function which has been lost.
The most common class of medications used to treat dementias inhibits the breakdown of a chemical in the brain known as acetylcholine. Medications in this class include Aricept, Razadyne and Exelon. Another medication known as Namenda was approved for use in advanced dementias in 2003. This medication is generally used in combination with Aricept, Razadyne and Exelon. Research aimed at discovering new methods of treating these diseases is ongoing.
Other medications are available to help with the symptoms of agitation, depression, anxiety and delusions. All treatments are aimed at lessening these symptoms.