Dementia is an umbrella term for a group of cognitive disorders typically characterized by memory impairment, as well as marked difficulty in the domains of language, motor activity, object recognition, and disturbance of executive function – the ability to plan, organize, and abstract. Generally speaking, dementia is an illness of older adults, which suggests that as successive cohorts of our population live longer, the urgency to better address dementia increases. Medications addressing pathologies in neurotransmission underlying dementia have been used with modest – and generally short-term -- success in forestalling the usual progression of these disorders.
Alzheimer's disease is perhaps the most common form of dementia, although several others exist. Alzheimer’s disease is a progressive disease of the brain. In the early stages, people experience some memory loss which progresses to marked memory loss, then to a decrease in thinking ability such as decision making. Later the disease leads to the loss in the ability to perform activities of daily living or recognize loved ones. The changes in the brain that often mirror the decline in thinking are the development of plaques and tangles in the brain. These changes may begin in areas of the brain associated with memory, but later spread more widely throughout the brain.1 The plaques and tangles can lead to a gradual loss of connections between brain cells and eventually cell death2.
Alzheimer’s disease usually occurs in individuals who are 60 years old and older3. Starting at age 65, the risk of developing the disease doubles every five years. By age 85 years and older, between 25 and 50 percent of people will exhibit signs of Alzheimer’s disease. Up to 5.3 million Americans currently have Alzheimer’s disease4. By 2050, the number is expected to more than double due to the aging of the population. Alzheimer’s disease is the sixth leading cause of death in the United States and is the fifth leading cause among persons age 65 and older5.
There are a number of studies that suggest behaviors that might lessen the risk of developing the disease. Among these are increasing physical activity, having a diet rich in fruits and vegetables, maintaining social engagement, and participating in intellectually stimulating activities. Some studies suggest that the prevention of diseases that damage blood vessels such as heart disease, stroke, and type 2 diabetes may also lessen the risk of Alzheimer’s disease. Other studies are investigating the use of vitamin C and E as well as nonsteroidal anti-inflammatory drugs such as ibuprofen, naproxen, and indomethacin. We must await the outcome of ongoing studies to assess the effectiveness of these measures. The approved treatments for Alzheimer’s disease are designed to enhance the communication between nerve cells. In some individuals, this will lessen the symptoms. However, these treatments will not prevent the progression of the disease.
In addition to Alzheimer’s disease, there are several other diseases that are characterized by dementia symptoms, including vascular dementia, Lewy body dementia, frontotemporal dementia, Huntington’s disease, and Creutzfeldt-Jakob disease. Vascular dementia is a common cause of dementia and is a result of brain damage from cerebrovascular or cardiovascular problems, such as strokes or endocarditis. Lewy body dementia is a progressive form of dementia that involves the death of cells in the brain’s outer layer and part of the mid-brain. Many of the surviving cells in these areas contain abnormal structures called Lewy bodies. Frontotemporal dementia is associated with the degeneration of nerve cells in the frontal or temporal lobes of the brain. Huntington’s disease is a hereditary disorder that causes degeneration in the brain and spinal cord. Creutzfeldt-Jakob disease is believed to be caused by an abnormal form of the prion protein6,7.
Dementia - Other Causes
Other conditions can also cause dementia or dementia-like symptoms including reactions to medications, nutritional deficiencies, infections, poisoning, brain tumors, and anoxia or hypoxia (conditions in which the brain’s oxygen supply is either reduced or cut off entirely). In many cases, the condition is reversible with treatment, therefore alleviating the dementia or dementia-like symptoms6,7.
- Waldemar G, Dubois B, Emre M, et al. "Recommendations for the diagnosis and management of Alzheimer's disease and other disorders associated with dementia: EFNS guideline". Eur J Neurol 2007;14: e1–26. doi:10.1111/j.1468-
- Tiraboschi P, Hansen LA, Thal LJ, Corey-Bloom J . "The importance of neuritic plaques and tangles to the development and evolution of AD". Neurology 2004;62 (11): 1984–9. PMID15184601.
- Alzheimer’s Association. Early-Onset Dementia: A National Challenge, A Future Crisis. (Washington, D.C.: Alzheimer’s Association, June 2006). Available at www.alz.org.
- Hebert L, Scherr PA, Bienias JL, Bennett DA, Evans DA. Alzheimer disease in the US Population. Arch Neurol. 2003;60:1119-1122.
- Heron, MP; Hoyert, DL; Murphy, SL; Xu, JQ; Kochanek, KD;Tejada-Vera, B. “Deaths: Final data for 2006.” National Vital Statistics Reports Vol. 57, No. 14., Hyattsville, Md.: National Center for Health Statistics, 2009.
- National Institute of Neurological Disorders and Stroke. (2011). Dementia Information Page, Retrieved May 4, 2011 from http://www.ninds.nih.gov/disorders/dementias/dementia.htm.
- National Institute of Neurological Disorders and Stroke. (2011). Dementia Hope Through Research, Retrieved May 4, 2011 from http://www.ninds.nih.gov/disorders/dementias/detail_dementia.htm