Andrey Nailor, M.D.·Published 27 June 2011·13 min read
Key points
The topic of dementia received little attention in the medical literature until about 70 years ago.
People's interest in the topic is evidenced by the fact that the Internet bookseller Amazon.com lists more than 25,000 titles that include the word dementia.
This prevalence is expected to nearly triple, to 13.3 million, by 2050.
The syndrome now known as dementia is a phenomenological diagnosis that is based on clinical observation.
The topic of dementia received little attention in the medical literature until about 70 years ago. The U.S. National Library of Medicine's PubMed Web site listed only 3 references to dementia in 1935, a total of 25 in 1950, and approximately 550 in 1960. By 2007, there were over 90,000 references. Within the past 30 years, the general public has become familiar with dementia, in large measure due to the efforts of the Alzheimer's Association.
People's interest in the topic is evidenced by the fact that the Internet bookseller Amazon.com lists more than 25,000 titles that include the word dementia.
With regard to a specific disease, the prevalence of Alzheimer disease in the United States (estimated from a population-based, biracial urban study converted to prevalence estimates and applied to the U.S. population) was 4.5 million in 2000 by one widely accepted estimate (Hebert el al. 2003). This prevalence is expected to nearly triple, to 13.3 million, by 2050. If Alzheimer disease accounts for 56% of dementia cases, as indicated in the Framingham Study (Bachman et al. 1992), the total number of elderly persons in the United States with dementia in 2000 was more than 8 million. A 15-year epidemiological study that initially enrolled more than 1,600 nondemented persons age 65 years or older found that 5% of the deaths were attributed to Alzheimer disease, with an average time from onset to death of 5.9 years (Ganguli et al. 2005). Thus, Alzheimer disease and dementing illness in general are important public health issues, as discussed in Chapter 2 of this volume, "Epidemiology and Impact of Dementia."
History of Dementia
The syndrome now known as dementia is a phenomenological diagnosis that is based on clinical observation. It has had various names over the past 2,500 years, including paranoia, idiotism, fatuity, acquired imbecility, senility, senile psychosis, and chronic organic brain syndrome. Hippocrates (circa 400 B.C.) identified the brain as the locus of mental function and was the first to recognize disorders of mental function as diseases, which he divided into epilepsy, mania, melancholia, and paranoia, the last term being equivalent to mental deterioration (Zilboorg 1941).
Although the early symptoms of the syndrome we now call dementia are cognitive and behavioral, astute observers differentiated this syndrome from other mental syndromes on the basis that its early effects were on memory and reasoning, recovery was infrequent, effects on the motor system were late, and it often progressed to total loss of self-care and communication. Causality was of course an issue. It had been observed since antiquity that cognitive functioning might become impaired following head injury or in association with systemic disease, but that in some individuals no association (and therefore no presumed cause) could be found other than with the general deterioration of aging. It had also been observed that persons who lived to old age became increasingly impaired; eyesight and hearing faded, muscle mass and strength diminished, digestion and elimination slowed.
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Andrey Nailor, M.D.
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These observations gave rise to the concept of senility, the gradual wearing out of the organism. There is little doubt that individual organs and tissues do wear out over time; in fact, Drachman (2006a) recently presented an elegant argument for the role of entropy in late-onset Alzheimer disease. On the other hand, too ready an application of the wear-and-tear notion has concealed many of what we call diseases today. The attitude for which Robert Butler (1969) coined the term ageism had for many years discouraged inquiry into what appeared to be the "natural" process of physical and mental deterioration and the equation of old age to ill health.
The term dementia, which we now use to describe acquired global cognitive impairment (as opposed to amentia, or cognitive impairment evident from birth), is derived from the Latin de (out of ) + mens (mind) + ia (state of ); it literally means a state of being out of or deprived of one's mind. It is one form of lunacy or insanity; the latter term was still in medical use through the 1920s as the overarching term for severe mental disorders.
The historical origin of the term dementia is unclear. Although attributed by Lipowski (1980) to Celsus in the first century A.D., the term does not appear in an English translation of Celsus's (1756) De Medicina. The poet Juvenal, in the first or second century, is said to have used dementia in reference to the mental decrepitude of old age (Lipowski 1980), but the term was used through the nineteenth century (Thomas 1889) and is still used among the lay public today to designate mental derangements of many kinds. For example, someone might report, "The demented killer stalked his victims with great care and forethought before committing the horrible crime." If the killer had been truly demented, this could hardly have been the case.
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The first reference to an association between aging and dementia (i.e., senile dementia) was made by Aretaeus of Cappadocia in the second century. In describing the aging process, he used the term dotage to mean "a torpor of the senses and a stupefaction of the gnostic and intellectual faculties" that accompanies old age (Aretaeus 1861, p. 301). From at least this point in time, the distinction between normal brain aging and late-life brain disease has been unclear. For example, according to Folsom (1886),
Senile dementia is simply an excess of the natural weak- ness of old age out of proportion to the bodily state, an exaggerated childishness of senility to the extent of pro- ducing irresponsibility... Memory fails first, and a con- dition of general weakness of mind follows rapidly af- terward. Secretiveness, suspicions, delusions and hallucinations of the special senses are almost always present. (p. 174)
He went on to say (presaging recognition of the frontotemporal dementias and their differentiation from Alzheimer disease),
It is not uncommon for the early symptoms to consist in an inhibition of the higher faculties of the mind, so that the lower impulses become prominent. The sense of right and wrong and the moral perceptions may become entirely weakened. Acts of indecency, dishonesty, injus- tice and depravity may follow impaired judgment, and yet so far precede strikingly perverted memory and gen- eral intelligence as to make the insanity (e.g., mental dis- order) which is obvious to an experienced observer, fail entirely to impress itself on the minds of the community. (Folsom 1886, p. 174)
Philippe Pinel, who in the late 18th century became superintendent of the Parisian psychiatric hospitals named the Bicêtre and the Salpetrière (saltpeter factory), used the term demence (i.e., dementia) to designate one of the five classes of mental derangement. Although it is described as the derangement that abolishes the thinking faculty, dementia appeared to refer to schizophrenia and other psychotic disorders formerly classified as functional psychoses (Pinel 1806/1962, p. 165). Pinel's class of derangement that most closely corresponds to the DSM-IV-TR (American Psychiatric Association 2000) category of dementia was "idiotism, an obliteration of the intellectual facilities and affections" (Pinel 1806/1962, p. 165). Esquirol (1845/1965), Pinel's successor at the Salpetrière, used dementia to describe mental disorders that were manifested by weakened sensibility, understanding, and will, with impaired recent memory, attention, reasoning, and abstracting ability. He described the dementias as acute, chronic, and senile, and included end-stage psychotic disorders and stuporous depression in this category. American physician Benjamin Rush (1812) used the term fatuity to designate the mental disorder characterized primarily by impaired reasoning and memory. James Prichard (1837), an English physician who did not regard dementia as a normal consequence of old age, suggested that dementia might be primary or secondary to other disorders and delineated a four-stage natural history of dementia that parallels the course of Alzheimer disease: 1) loss of recent memory with preservation of remote memory, 2) loss of reason, 3) loss of comprehension, and 4) loss of ability to care for vegetative functions.
Dementia has long had important legal implications as a type of insanity; insanity is now exclusively a legal term for a condition in which, as a result of a profound disturbance in the intellectual facilities, a person has lost more or less completely his or her free will and has ceased thereby to be responsible to society for his or her actions.
As a result of their diminished capacity to make judgments and direct their own behavior, demented persons were classed under English law as non compos mentis or lunatics (Prichard 1837, p. 254) and were held to have diminished responsibility/capacity in relation to the severity of their mental impairment. For this reason, the term insanity still persists in legal proceedings, but it was clear to many from the latter part of the 19th century that insanity was in fact the result of a brain disorder (Folsom 1886, p. 104). The first attempts to quantify dementia severity arose because of the need to quantify legal capacity.
Perhaps the earliest schema for quantifying dementia was developed by Hoffbauer (cited by Prichard 1837, pp. 256-261). It included the categories of bloedsinn (translated from the German by Prichard as "silliness") and dumbest (translated as "stupidity"), which are roughly equivalent to executive deficit and intellectual deficit, respectively. The primary characteristic of silliness was impaired judgment, again anticipating the recognition of frontal lobe syndromes. The primary characteristic of stupidity was inability to acquire and retain information.
Stages of silliness, from most to least impaired, included 1) inability to judge new situations, 2) inability to judge familiar situations, 3) marked impairment of memory and attention, 4) clouding of consciousness, and 5) stupor and unresponsiveness. The three stages of stupidity began with the inability to weigh opposites, progressed through the inability to reason, and culminated in the inability to express ideas in language.
Emil Kraepelin (1913) distinguished the so-called functional psychoses from the consequences of obvious brain damage, calling the former the insanities and the latter varieties of imbecility. The two categories of imbecility were acquired imbecility (dementia) and congenital (ordinary) imbecility. The dementia category included apoplectic dementia due to vascular disease, old age (or senil- ity), and epilepsy.
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Eugen Bleuler (1924), in a discussion of the organic psychoses, defined an organic psychosyndrome as a set of behavioral manifestations of chronic, diffuse damage to the cerebral cortex that could be due to a variety of causes, including trauma, infection (specifically, syphilis), toxins, arteriosclerosis, and senility. Its manifestations were impairments in memory, judgment, perceptual discrimination, orientation, emotional stability, and impulse control.
Bleuler recognized that all cognitive functions were not equally affected, that long-practiced abilities were the most resistant to deterioration, and that some causes of the organic psychosyndrome were still to be discovered.
He also noted that variations in the form of the psychosyndrome could be related to genetic factors such as a tendency toward complicating mood disorder in demented persons with a family history of mood disorder. Finally, he pointed out that the course of the organic psychosyndrome was related to the underlying illness, that, for example, the Korsakoff syndrome might improve slightly and remain stable, and that episodes of apparent remission might occur in neurosyphilis and arteriosclerotic brain disease.
Bleuler's textbook contains descriptions of the senile and presenile insanities. Classed under dementia senilis are arteriosclerotic insanity and simple atrophy of the brain. Simple dementia senilis is described as a product of "the normal regression of the brain that begins in the 50s, but is not usually notable until the last decade of the normal life span" (Bleuler 1924, p. 286) (the actual length of the normal life span is not indicated). The brain shrinks, the ventricles enlarge, and there is disappearance of ganglion (pyramidal) cells. The clinical signs, in order of appearance, are 1) inability to assimilate the ideas of others, 2) increased egocentricity and stubbornness, and 3) confabulation. Bleuler (1924) also set forth the category of presbyophrenia (a term he attributed to Kahlbaum), a dementing disorder of old age characterized by constant motor activity, with pacing and repeated performance of meaningless activities. Here, the pathology was said to be senile plaques surrounded by degenerating fibrils (the neuritic plaques of today), whereas in Alzheimer disease, the pathology was said to be more intense, with rapid development of aphasia, agnosia, and apraxia.
At mid-twentieth century, Roth and Morrissey (1952) wrote that resulting from the work of Alzheimer, Kraepelin, Binswanger, Pick, and others, the mental diseases peculiar to old age had, since the beginning of the century, been subdivided into the senile, arteriosclerotic, and presenile psychoses (psychosis in this case meaning a mental disorder of sufficient severity to interfere with meeting the demands of everyday life). They regarded Alzheimer and Pick diseases as rare presenile illnesses. Roth and Morrissey described the core syndrome of senile psychosis as beginning with selective impairment of recent memory and attention and faulty location of recent events in time, followed by euphoria, confabulation, and an illsystematized paranoid element deriving from failure of memory. They recognized that this symptom complex could be the clinical manifestation of a number of underlying brain diseases. In the same paper, Roth and Morrissey reported on the 3-year survival of 150 consecutive persons age 60 years or older who had been admitted to Graylingwell Hospital in 1948. Of those with affective diagnoses, less than 25% were dead; however, 90% of those diagnosed with senile psychosis had died. Despite the fact that the modal patient with an affective disorder diagnosis was in the age range 60-65 years and the modal patient with senile psychosis was in the age range 75-79 years, this finding was probably the first statistical proof of the lethality of senile psychosis.
It has long been recognized that there is an indistinct border between what Ferrara (1959) termed psychological/ physiological senescence (the effects of normal social/brain aging) and pathological senescence (dementia). Ferrara stated that as physiological and psychological senescence gradually drifts into pathological senescence, perceptual and memory impairments are often encountered, and that impaired perception, impaired registration, and decreased impressionability often mark the onset of a senile dementia. "From a practical standpoint, one may speak of dementia when the disturbance of memory is such as to render fragmentary or falsify entirely the relationship of the patient to his surroundings" (Ferrara 1959, p. 1025).
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As the etiologies of various dementing illnesses have been elucidated and treatments developed, the prevalence and impact of these illnesses have changed. For example, general paralysis of the insane (now termed neurosyphilis) was described by Thomas Willis in 1672 as a syndrome beginning with mania and followed by dementia and paralysis, but the paralysis was thought to be a late, nonspecific concomitant of mental disease. In 1826, Bayle recognized the entire cluster of signs and symptoms as a specific entity. The relationship of this syndrome to syphilis was hotly debated until 1913, when the spirochete Treponema pallidum was demonstrated in the brains of persons with general paresis by Noguchi and Moore, and the term neurosyphilis came into use (Henry 1941). Since the 1940s, with the widespread use of serological tests to detect early syphilis and the availability of penicillin for treatment, neurosyphilis has become relatively rare in the United States. In fact, the rate of first admissions to psychiatric hospitals because of neurosyphilis fell from 4.3/ 100,000 population in 1946 to 0.4/100,00 in 1960 (Adams and Victor 1989, p. 573).
The prevalence and impact of dementia due to metabolic causes have also changed as a result of medical discoveries. Wilson disease is now treatable, the dementia of AIDS (acquired immunodeficiency syndrome) is largely preventable, and obstructive hydrocephalus due to meningitis can be relieved surgically. Early conjectures about the relationship between alcohol consumption and dementia may have implicated the wrong agent. Despite the association of dementia with repeated episodes of delirium tremens noted in the 19th century (Wilson 1886), Victor et al. (1989) found no evidence for direct toxicity of alcohol at postmortem examination of persons diagnosed during life as having alcoholic dementia. Instead, they demonstrated the stigmata of the thiamin deficiency-related Wernicke syndrome and other unrelated conditions, including trauma and Alzheimer disease. Thus, the primary cause of dementia in alcoholics appears to be malnutrition rather than the direct toxic effect of alcohol on the brain.
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Myron F. Weiner, M.D. Clinical Professor of Psychiatry and Neurology, Aradine S. Ard Chair in Brain Science, Dorothy L. and John P. Harbin Chair in Alzheimer's Disease Research, University of Texas Southwestern Medical Center at Dallas, Texas ###
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