In 1948, the Committee on Nomenclature and Statistics of the American Psychiatric Association undertook amalgamating the various existing nomenclatures; those efforts culminated in the publication of the Diagnostic and Statistical Manual of Mental Disorders (DSM-I; American Psychiatric Association 1952). In DSM-I, mental disorders were divided into two major groups: 1) those in which disturbance of mental function resulted from impaired brain function and 2) those in which altered brain function resulted from a more general difficulty in adaptation. The disorders caused by or associated with impairment of brain tissue function included two categories: acute (reversible) brain disorders and chronic (irreversible or only partially reversible) brain disorders.
Both of these categories were subdivided according to the underlying disease or condition, the latter including Alzheimer disease, at the time considered as a disease of presenile onset, and chronic brain syndrome, which was associated with senile brain disease. The 1948 edition of The Manual of the International Statistical Classification of Diseases, Injuries and Causes of Death (World Health Organization 1948) had included the categories of presenile psychosis (which excluded so-called presenile brain diseases such as Alzheimer and Pick disease), senile psychosis, and psychosis with cerebral arteriosclerosis.
The nomenclature of DSM-II (American Psychiatric Association 1968) was coordinated with the 1967 publication of the International Classification of Diseases, 8th Revision (ICD-8; World Health Organization 1967). In DSM-II, organic brain syndromes were listed in two categories: psychoses associated with organic brain syndromes and nonpsychotic organic brain syndromes. The term psychosis was used to indicate that the condition described sufficiently impaired mental functioning to interfere grossly with the capacity to meet the ordinary demands of life (p. 23). The term dementia, which did not appear in DSM-I, appeared in the categories of senile dementia and presenile dementia. Acute and chronic became modifying terms.
DSM-III (American Psychiatric Association 1980) stated that differentiation of organic mental disorders as a separate class did not imply that nonorganic (e.g., functional) mental disorders are independent of brain processes. Under the category of organic mental disorders was the subcategory of organic brain syndromes, a group of phenomenological diagnoses unrelated to underlying disease. These syndromes were grouped into six categories, one of which was delirium and dementia, in which cognitive impairment is relatively global. Other categories included amnestic syndrome and organic hallucinosis, organic delusional syndrome and organic affective syndrome, organic personality syndrome, intoxication and withdrawal, and atypical or mixed. This section was followed by the individual organic mental disorders, includ ing primary degenerative dementia (Alzheimers disease) and multi-infarct dementia.Dementia and Alzheimer Disease 13 DSM-IV (American Psychiatric Association 1994) replaced the category of organic mental disorders with the category of delirium, dementia, and amnestic and other cognitive disorders, because the term organic mental disorders implied that the other disorders in the manual did not have an organic component. An additional important change in DSM-IV was introduction of the phrase, due to … This phrase indicated that the clinician, in addition to describing the psychiatric symptom cluster, needs to attempt an identification of the underlying pathophysiological process. This phrase is also used in DSM-IV-TR (American Psychiatric Association 2000) and brings us back to the notion proposed first by Hippocrates and reaffirmed 2,000 years later by the German physician Wilhelm Griesinger in 1845 that all mental disorders are diseases of the brain (Zilboorg 1941).
There are still many unanswered and perhaps unanswerable questions with regard to the nosology of disease in general and dementia in particular. How far can nominalistic categorization be carried before it becomes trivial or moot? For example, is it of any heuristic value to code dementia of the Alzheimer type as with early onset or with late onset? The International Statistical Classification of Diseases and Related Health Problems, 10th Revision (ICD-10), continues to have a residual category of presenile and senile dementia (World Health Organization 1992). To what end? Is this not the same disease? However, if we did not continue this process and attempt to make increasingly fine distinctions, we probably, for example, would have failed to detect and distinguish those frontotemporal dementias whose basis is abnormal metabolism of the microtubule-associated protein tau from Alzheimer disease, whose pathophysiology appears related to errors in the metabolism of the amyloid precursor protein embedded in every human cell membrane (Boeve 2006). Or is it? Drachman (2006a) suggested that instead of a single metabolic defect underlying all of what is now seen as a single disease, there may be multiple age-dependent factors in late-onset sporadic disease that may be unique to each individual, depending on that persons vulnerability or cognitive reserve. But what about the effects of aging?
Cannot the nervous system simply wear out over time?
Our job is to sort out the potentially remediable causes of human disability and suffering from the inevitable organ failure and death of human beings. It is a daunting task that begins with astute clinical observation and classification.