Medically reviewed byDavid Cohen, M.D.Updated 18 July 201016 min read
Key points
In a world of ever-growing cognitive complexity, the threat of Alzheimer disease and other cognitive impairments that seem an inevitable part of aging is, on one hand, frightening, and on the other, a call to arms.
Dementia refers to a loss of cognitive function (cognition) due to changes in the brain caused by disease or trauma.
Some dementia is reversible and can be cured partially or completely with treatment.
An estimated 2 million people in the United States suffer from severe dementia and another 1 to 5 million people experience mild to moderate dementia.
In a world of ever-growing cognitive complexity, the threat of Alzheimer disease and other cognitive impairments that seem an inevitable part of aging is, on one hand, frightening, and on the other, a call to arms. We are faced with an increasing number of persons with dementia around the world, both in absolute numbers and in percentage of the population. This rise is in part due to greater survival of the normally aging world population and persons with chronic illnesses, head injuries, and other factors affecting brain function. As you will read on our site, our awareness of dementia has a long history with wide and varied attribution from immorality to evil. From these primitive beginnings, the community of clinicians and scientists has moved to an age of reasoning and inquiry that has created a nosology and diagnostic criteria, developed a knowledge of accompanying pathology, designed trials to test treatments, evaluated psychosocial interventions, provided support to caregivers, and championed the work to preserve the quality of life of those who are afflicted. There has been a virtual explosion of knowledge concerning the dementias in the past 30 years, and scarcely a day goes by that the media fail to mention the possibility of a new treatment for Alzheimer disease.
Dementia refers to a loss of cognitive function (cognition) due to changes in the brain caused by disease or trauma. The changes may occur gradually or quickly; and how they occur may determine whether dementia is reversible or irreversible.
Cognition is the act or process of thinking, perceiving, and learning. Cognitive functions that may be affected by dementia include the following:
Decision making, judgment
Memory
Spatial orientation
Thinking, reasoning
Verbal communication
Dementia also may result in behavioral and personality changes, depending on the area(s) of the brain affected.
Types of Dementia
Some dementia is reversible and can be cured partially or completely with treatment. The degree of reversibility often depends on how quickly the underlying cause is treated.
Irreversible dementia is caused by an incurable condition (e.g., Alzheimer's disease). Patients with irreversible dementia are eventually unable to care for themselves and may require round-the-clock care.
Incidence and Prevalence of Dementia
An estimated 2 million people in the United States suffer from severe dementia and another 1 to 5 million people experience mild to moderate dementia. Five to eight percent of people over the age of 65 have some form of dementia and the number doubles every 5 years over age 65.
The prevalence of dementia has increased over the past few decades, either because of greater awareness and more accurate diagnosis, or because increased longevity has created a larger population of elderly, which is the age group most commonly affected. In September 2009, it was estimated that as many as 35 million people throughout the world have some type of dementia.
Alzheimer's is the most common form of dementia, a general term for memory loss and other intellectual abilities serious enough to interfere with daily life. Alzheimer's disease accounts for 60 to 80 percent of dementia cases.
Alzheimer's is not a normal part of aging, although the greatest known risk factor is increasing age, and the majority of people with Alzheimer's are 65 and older. But Alzheimer's is not just a disease of old age. Up to 5 percent of people with the disease have early onset Alzheimer's (also known as younger-onset), which often appears when someone is in their 40s or 50s.
Alzheimer's worsens over time. Alzheimer's is a progressive disease, where dementia symptoms gradually worsen over a number of years. In its early stages, memory loss is mild, but with late-stage Alzheimer's, individuals lose the ability to carry on a conversation and respond to their environment. Alzheimer's is the sixth leading cause of death in the United States. Those with Alzheimer's live an average of eight years after their symptoms become noticeable to others, but survival can range from four to 20 years, depending on age and other health conditions.
Alzheimer's has no current cure, but treatments for symptoms are available and research continues. Although current Alzheimer's treatments cannot stop Alzheimer's from progressing, they can temporarily slow the worsening of dementia symptoms and improve quality of life for those with Alzheimer's and their caregivers. Today, there is a worldwide effort under way to find better ways to treat the disease, delay its onset, and prevent it from developing.
What is Frontotemporal Dementia?
Frontotemporal dementia (FTD) is a group of related conditions resulting from the progressive degeneration of the temporal and frontal lobes of the brain. These areas of the brain play a significant role in decision-making, behavioral control, emotion and language.
Forms of Frontotemporal Dementia
Behavioral variant FTD
Behavioral variant frontotemporal dementia (bvFTD) has also been referred to as "frontal variant FTD" (fvFTD) or "Pick's disease." Approximately 60% of people with any form of FTD have bvFTD. By definition, this form of FTD affects social skills, emotions, personal conduct, and self-awareness. Deficits in these functions most often reflect damage to specific regions within the frontal and temporal lobes. With damage to these areas, people may show mood and behavior changes including stubbornness, emotional coldness or distance, apathy and selfishness. Unlike Alzheimer's disease, which affects a different area of the brain, many people with bvFTD don't show any confusion or forgetfulness about where they are or what day it is, at least at first.
Semantic dementia
Semantic dementia, which has also been called "temporal variant FTD," accounts for 20% of FTD cases. Language difficulty, the predominant complaint of people with SD, is due to the disease damaging the left temporal lobe, an area critical for assigning meaning to words. The language deficit is not in producing speech but is a loss of the meaning, or semantics, of words. At first, you might notice someone substituting a word like "thingy" for more unusual words, but eventually a person with SD will lose the meaning of more common words as well. For example, early in the illness a patient might lose the word for a falcon, later-on forget the word for a chicken, then call all winged creatures "bird" and eventually call all animals "things." Not only do they lose the ability to recall the word, but the concept of these words is also lost. "What is a bird?" might be a typical response for a patient with advanced SD. Reading and spelling usually decline as well, but the person may still be able to do arithmetic and use numbers, shapes or colors well. Names of people, even good friends, can become quite difficult for people with SD. Like the behavioral variant, memory, an understanding of where they are, and sense of day and time tend to function as before. Muscle control for daily life and activities tends to remain good until late in the disease. Some of these skills may seem worse than they actually are because of the language difficulty people with SD have when they try to express themselves.
When SD starts in the right temporal lobe, people in the early stages have more trouble remembering the faces of friends and familiar people. Additionally, these people show profound deficits in understanding the emotions of others. The loss of empathy is an early, and often initial, symptom of patients with this right-sided form of SD. Eventually people with right-sided onset progress to the left side and then develop the classical language features of SD. Similarly, left-sided cases progress to involve the right temporal lobe and then the person experiences difficulty recognizing faces, foods, animals and emotion. SD patients eventually develop classical bvFTD behaviors including disinhibition, apathy, loss of empathy and diminished insight. The time from diagnosis to the end is longer than for those with bvFTD, typically taking about six years.
Progressive nonfluent aphasia
PNFA accounts for only about 20% of all people with FTD. Unlike semantic dementia where the person maintains the ability to speak but loses the meaning of the word, people with PNFA have difficulty producing language fluently even though they still know the meaning of the words they are trying to say. The person may talk slowly, having trouble saying the words, and have great trouble with the telephone, talking within groups of people or understanding complex sentences. In recent years it has become apparent that many patients with PNFA go on to develop severe Parkinsonian symptoms that overlap with progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD) such as an inability to move the eyes side-to-side, muscle rigidity in the arms and legs, falls, and weakness in the muscles around the throat.
Symptoms of Alzheimer's
The most common early symptom of Alzheimer's is difficulty remembering newly learned information.
Just like the rest of our bodies, our brains change as we age . Most of us eventually notice some slowed thinking and occasional problems with remembering certain things. However, serious memory loss, confusion and other major changes in the way our minds work may be a sign that brain cells are failing.
The most common early symptom of Alzheimer's is difficulty remembering newly learned information because Alzheimer's changes typically begin in the part of the brain that affects learning. As Alzheimer's advances through the brain it leads to increasingly severe symptoms, including disorientation, mood and behavior changes; deepening confusion about events, time and place; unfounded suspicions about family, friends and professional caregivers; more serious memory loss and behavior changes; and difficulty speaking, swallowing and walking.
People with memory loss or other possible signs of Alzheimer's may find it hard to recognize they have a problem. Signs of dementia may be more obvious to family members or friends. Anyone experiencing dementia-like symptoms should see a doctor as soon as possible.
How common is Alzheimer's disease?
One in 10 people older than 65 and nearly half of people older than 85 have Alzheimer's disease. AD can affect people in their 40s. The percentage of people who have AD rises every decade beyond the age of 60.
While AD is the most common cause of dementia (accounting for 62 percent to 70 percent of cases), there are other causes. These include:
Frontotemporal dementia
Parkinson's or Huntington's disease
Dementia with Lewy bodies
Vascular dementia
Kidney or liver disease
Vitamin B12 deficiency
Thyroid problems
Bad reaction to medication
Drug or alcohol abuse
Psychiatric disorders
As the field of dementia research has progressed, our understanding of different entities has grown, initially focusing on clinical and neuropathological distinctions of frontotemporal dementias and conditions associated with Lewy bodies. Each of these dementias has come under considerable study with many efforts to establish and revise consensus criteria as new information has come forward. These global efforts ensure a common language to describe serious conditions and lay the foundation to systematically study treatments and management for each.
In fact, starting with the earliest efforts to create research criteria for Alzheimer disease, the field has made remarkable strides in developing treatments. It should be recalled that less than 20 years ago there were no approved treatments, and while the search for more effective treatments and cures goes forward, the Alzheimer patient of today can expect to be offered one of several drugs approved for the treatment of their disease. Approval for the treatment of other dementias has been made possible by the establishment and recognition of diagnostic criteria and development of sound clinical trial design.
References
Adams RD, Victor M: Principles of Neurology, 4th Edition. New York, McGraw-Hill, 1989
Alzheimer A: About a peculiar disease of the cerebral cortex (1907). Translated by Jarvik L, Greenson H. Alzheimer Dis Assoc Disord 1:7-8, 1987
Alzheimer's Association: Milestones. 2008. Available at: http://www.alz.org/about_us_milestones.asp. Accessed April 21, 2008.
American Psychiatric Association: Diagnostic and Statistical Manual: Mental Disorders. Washington, DC, American Psychiatric Association, 1952
American Psychiatric Association: Diagnostic and Statistical Manual of Mental Disorders, 2nd Edition. Washington, DC, American Psychiatric Association, 1968
American Psychiatric Association: Diagnostic and Statistical Manual of Mental Disorders, 3rd Edition, Revised. Washington, DC, American Psychiatric Association, 1980
American Psychiatric Association: Diagnostic and Statistical Manual of Mental Disorders, 4th Edition. Washington, DC, American Psychiatric Association, 1994
American Psychiatric Association: Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision. Washington, DC, American Psychiatric Association, 2000
Aretaeus: The Extant Works of Aretaeus, the Cappadocian. Edited by London F. London, Syndenham Society, 1861
Bachman DL, Wolf PA, Linn, R, et al: Prevalence of dementia and probable senile dementia of the Alzheimer type in the Framingham Study. Neurology 42:115-119, 1992
Bleuler E: Textbook of Psychiatry. Translated by Brill AA. New York, Macmillan, 1924
Boeve BF: A review of the non-Alzheimer dementias. J Clin Psychiatry 67:1985-2001, 2006Dementia and Alzheimer Disease 15
Butler RN: Age-ism: another form of bigotry. Gerontologist 9:243-246, 1969
Celsus AC: De Medicina (c. 100 A.D.). Translated by Greive J. London, Wilson and Durham, 1756
Corder EH, Saunders AM, Strittmatter WJ: Gene dose of apolipoprotein E type 4 allele and the risk of Alzheimer's disease in late onset families. Science 261:921-923, 1993
Corsellis JAN: Mental Illness and the Aging Brain. London, Oxford University Press, 1962
Crook T, Gershon S: Strategies for the Development of an Effective Treatment for Senile Dementia. New Canaan, CT, Mark Powley Associates, 1981
Crook T, Bartus R, Ferris S, et al: Treatment Development Strategies for Alzheimer's Disease. New Canaan, CT, Mark Powley Associates, 1986
Davies P, Maloney AJ: Selective loss of central cholinergic neurons in Alzheimer's disease. Lancet 2:1403, 1976
Davis KL, Mohs RC: Enhancement of memory processes in Alzheimer's disease with multiple-dose intravenous physostigmine. Am J Psychiatry 139:1421-1424, 1982
Davis KL, Mohs RC, Tinklenberg JR, et al: Physostigmine improvement of long-term memory processes in normal humans. Science 201:272-274, 1978
Davis KL, Thal LJ, Gamzu ER, et al: A double-blind placebo-controlled multicenter study of tacrine for Alzheimer's disease. N Engl J Med 327:1253-1259, 1992
DeKosky ST, Scheff SW: Synapse loss in frontal cortex biopsies in Alzheimer's disease: correlation with cognitive severity. Ann Neurol 27:457-464, 1990
Deutsch JA: The cholinergic synapse and the site of memory. Science 174:788-794, 1971
Drachman D: Aging of the brain, entropy, and Alzheimer disease. Neurology 67:1340-1352, 2006a
Drachman D: Robert Katzman and Alzheimer's disease: an appreciation. Alzheimer Dis Assoc Disord 20 (suppl 2):S29-S30, 2006b
Drachman DA, Leavitt J: Human memory and the cholinergic system. Arch Neurol 30:113-121, 1974
Esquirol JED: Mental Maladies: A Treatise on Insanity (1845). Translated by Hunt EK. New York, Hafner, 1965
Ferrara A: Senile psychoses, in American Handbook of Psychiatry. Edited by Arieti S. New York, Basic Books, 1959, pp 1046-1077
Folsom CF: Mental diseases, in A System of Practical Medicine, Vol 5: Diseases of the Nervous System. Edited by Pepper W, Starr L. Philadelphia, PA, Lea Brothers, 1886, pp 99-204
Ganguli M, Dodge HH, Shen C, et al: Alzheimer disease and mortality: a 15-year epidemiological study. Arch Neurol 62:779-784, 2005
Glenner GC, Wong CW: Alzheimer's disease: initial report of the purification and characterization of a novel cerebrovascular amyloid protein. Biochem Biophys Res Commun 120:885-890, 1984a
Glenner GC, Wong CW: Alzheimer's disease and Down's syndrome: sharing of a unique cerebrovascular amyloid fibril protein. Biochem Biophys Res Commun 122:1131-1135, 1984b
Goedert M, Spillantini MG: A century of Alzheimer's disease. Science 341:777-781, 2006
Hebert LE, Scherr PA, Bienias JL, et al: Alzheimer disease in the US population: prevalence estimates using the 2000 census. Arch Neurol 60:1119-1122, 2003
Henry GW: Organic mental diseases, in A History of Medical Psychology. Edited by Zilboorg G, Henry GW. New York, WW Norton, 1941, pp 526-557
Katzman R: The prevalence and malignancy of Alzheimer's disease: a major killer. Arch Neurol 33: 217-218, 1976
Katzman R, Bick K: Alzheimer Disease: The Changing View. San Diego, Academic Press, 2000
Kay DWK: Outcome and cause of death in mental disorders of old age: a long-term follow-up of functional and organic psychoses. Acta Psychiatr Scand 38:249-276, 1962
Khachaturian Z: History of Alzheimer's research: the politics of science in building a national program of research. Alzheimer Dis Assoc Disord 20 (suppl 2):S31-S34, 2006
Kidd M: Paired helical filaments in electron microscopy of Alzheimer's disease. Nature 197:192-193, 1963
Knopman DS, Parisi JE, Salviati A, et al: Neuropathology of cognitively normal elderly. J Neuropathol Exp Neurol 62:1087-1095, 2003
Korenberg JR, Pulst SM, Neve RL, et al: The Alzheimer amyloid precursor protein maps to human chromosome 21 bands q21.105-q21.05. Genomics 1:124-127, 1989
Kraepelin E: Psychiatrie: Ein lehrbuch fr Studierende und rtz. Leipzig, Verlag Johann Ambrosius Barth, 1910
Kraepelin E: Lectures on Clinical Psychiatry, 2nd Edition. Translated by Johnstone T. New York, William Wood, 1913
Krishnan KRR: Concept of disease in geriatric psychiatry. Am J Geriatr Psychiatry 15:1-11, 2007
Lipowski ZJ: Organic mental disorders: introduction and review of syndromes, in Comprehensive Textbook of Psychiatry, 3rd Edition, Vol 2. Edited by Kaplan HI, Freedman AM, Sadock BJ. Baltimore, MD, Williams & Wilkins, 1980, pp 1359-1391
Logie HB (ed): A Standard Classified Nomenclature of Disease. New York, The Commonwealth Fund, 1933
Maurer K: Historical background of Alzheimer's research done 100 years ago. J Neural Transm 113:1597-1601, 2006
McKhann G, Drachman D, Folstein M, et al: Clinical diagnosis of Alzheimer's disease: report of the NINCDS-ADRDA work group under the auspices of the Department of Health and Human Services Task Force on Alzheimer's Disease. Neurology 34:939-944, 1984
Mora G: Historical and theoretical trends in psychiatry, in Comprehensive Textbook of Psychiatry, 3rd Edition. Edited by Kaplan HI, Freedman AM, Sadock BJ. Baltimore, MD, Williams & Wilkins, 1980, pp 4-98
Morris JC, Rubin EH: Clinical diagnosis and course of Alzheimer's disease. Psychiatr Clin North Am 14:223-236, 1991
Mueller SG, Weiner MW, Thal LJ, et al: The Alzheimer's disease neuroimaging initiative. Neuroimaging Clin N Am 15:869-877, 2005
Newton RD: The identity of Alzheimer's disease and senile dementia and their relationship to senility. J Ment Sci 94:225-249, 1948
Petersen RC, Smith GE, Waring SC, et al: Mild cognitive impairment: clinical characteristics and outcome. Arch Neurol 56:303-308, 1999
Pinel P: A Treatise on Insanity (1806). New York, Hafner, 1962
Prichard JAC: A Treatise on Insanity. Philadelphia, PA, Haswell, Barrington, and Haswell, 1837
Ranginwala N, Hynan LS, Weiner MF: Clinical criteria for the diagnosis of Alzheimer disease: still good after all these years.
Poster presented at the annual meeting of the American Association for Geriatric Psychiatry, New Orleans, LA, March 2007
Rosen WG, Mohs RC, Davis KL: A new rating scale for Alzheimer's disease. Am J Psychiatry 141:1356-1364, 1984
Roth M, Morrissey JD: Problems in the diagnosis and classification of mental disorder in old age; with a study of case material. J Ment Sci 98:66-80, 1952
Roth M, Tomlinson BE, Blessed G: Correlation between scores for dementia and counts of "senile plaques" in cerebral gray matter of elderly subjects. Nature 209:109-110, 1966
Rush B: Medical Inquiries and Observations upon the Diseases of the Mind. Philadelphia, PA, Kimber and Richardson, 1812
Sim M, Sussman I: Alzheimer's disease: its natural history and differential diagnosis. J Nerv Ment Dis 135:489-499, 1962
Simchowitz T: La maladie d'Alzheimer et son rapport avec la demence senile. Encephale 9:218-231, 1914
St. George-Hyslop PH, Tanzi RE, Polinski PJ, et al: The genetic defect causing familial Alzheimer's disease maps in chromosome 21. Science 235:885-890, 1987
Summers WK, Vesselman JO, Marsh GM, et al: Use of THA in treatment of Alzheimer-like dementia: pilot study in twelve patients. Biol Psychiatry 16:146-153, 1981
Terry RD, Gonatas NK, Weiss M: Ultrastructural studies in Alzheimer's presenile dementia. Am J Pathol 44:269-297, 1964
Thomas J: A Complete Pronouncing Medical Dictionary. Philadelphia, PA, JB Lippincott, 1889
Tomlinson BE, Blessed G, Roth M: Observations on the brains of non-demented old people. J Neurol Sci 7:331-356, 1968
Tomlinson BE, Blessed G, Roth M: Observations on the brains of demented old people. J Neurol Sci 11:205-242, 1970
Victor M, Adams RD, Collins GH: The Wernicke-Korsakoff Syndrome and Other Disorders Due to Alcoholism and Malnutrition. Philadelphia, FA Davis, 1989
Walsh DM, Selkoe DJ: Abeta oligomers: a decade of discovery. J Neurochem 101:1172-1184, 2007
White P, Hiley CR, Goodhardt MJ, et al: Neocortical cholinergic neurons in elderly people. Lancet 1:668-671, 1977
Whitehouse PJ, Price DL, Struble AN, et al: Alzheimer's disease and senile dementia: loss of neurons in the basal forebrain. Science 215:1237-1239, 1981
Wilson JC: Alcoholism, in A System of Practical Medicine, Vol 5: Diseases of the Nervous System. Edited by Pepper W, Starr L. Philadelphia, PA, Lea Brothers, 1886, pp 573-646
World Health Organization: The Manual of the International Statistical Classification of Diseases, Injuries and Causes of Death. Geneva, World Health Organization, 1948
World Health Organization: International Classification of Diseases, 8th Revision. Geneva, World Health Organization, 1967
World Health Organization: International Statistical Classification of Diseases and Related Health Problems, 10th Revision. Geneva, World Health Organization, 1992
Zilboorg G: A History of Medical Psychology. New York, W.W. Norton and Company, 1941
Further Reading
Bick K, Amaduci L, Pepeu G: The Early Story of Alzheimer's Disease. Padua, Italy, Liviana Press, 1987
Jellinger KA: Alzheimer 100: highlights in the history of Alzheimer research. J Neural Transm 113:1603-1623, 2006
Katzman R, Bick K, Bick KL: Alzheimer Disease: The Changing View. New York, Academic Press, 2006
Lipowski ZJ: Organic mental disorders: their history and classification with special reference to DSM-III, in Aging, Vol 15: Clinical Aspects of Alzheimer' Disease and Senile Dementia. Edited by Miller NE, Cohen GD. New York, Raven Press, 1981, pp 37-46
Kenneth L. Davis, M.D.
President and CEO, Mount Sinai Medical Center, New
