We are grateful to Nancy Miller, Zbigniew Lipowski, and Barry Lebowitz for their outstanding work as guest editors of this issue of International Psychogeriatrics. These papers were stimulated by a special meeting of the National Institute of Mental Health (NIMH). They are authored by Americans and Canadians and are followed by discussions and critiques from experts in Europe, Australia, and Asia. This format is a novel one, but one which presents many exciting possibilities.

Interest in the health and diseases of elderly people has been growing in most parts of the world during the last few decades. One reason is that knowledge of normal aging and of the manifestations of disease in the higher age groups has been incomplete compared to the corresponding knowledge regarding other periods of human life. Another reason is the increasing absolute and relative number of elderly not only in the developed, but also importantly in the developing world. It is estimated, for example, that the increase of the population aged 80 and over from 1980 to 2020 will amount to 108% in the developed world compared to 377% in the developing world (U.N. Department of International Economic and Social Affairs, 1985).

The rapid growth of the field of psychogeriatrics, spurred on by aging populations, substantially increased funding, and growing interest by professionals, government, and society, has led, in turn, to a rapid growth of medical information. The management of this information poses a significant challenge to health care professionals and scientists. This rapid growth of knowledge has spawned a whole new field, “Medical Informatics.” This field concerns itself with the “cognitive, information processing, and communication tasks of medical practice, education and research, including the information science and the technology to support these tasks” (Greenes & Shortliffe, 1990).

The concept of dementia should not be used synonymously with the concept of organic mental disorders. By definition, according to DSM-III and ICD-10, dementia is a syndrome which includes memory impairment. The severity of the disorder is disabling and the course is chronic. Differential diagnosis includes age-associated memory impairment (AAMI), delirium, and depressive disorders. The dementias may be subdivided into four groups: idiopathic (primary degenerative dementias), vascular, secondary, and others. The idiopathic dementias are those in which etiology is assumed to be found within the brain itself. The main subgroup is Alzheimer-type dementia. The vascular dementias are those in which the blood supply to the brain is insufficient. Multi-infarct dementia (MID) is the prototype. In secondary dementias, somatic disorders either within or external to the brain cause the dementia.

While there is little question that advancing chronological age is intimately implicated in the brain's enhanced vulnerability to acute confusional states, the nature and dynamics of this relationship, until recently, have managed to escape sustained empirical scrutiny. Despite the fact that the syndrome has been described in the medical literature for over 2,000 years, despite the presence of many anecdotal reports on delirium in the clinical literature, and despite its long-rooted association with high rates of morbidity and mortality in senescence, surprisingly little hard data has been collected regarding distribution of the syndrome in the general population, critical aspects of differential diagnosis, the spectrum of syndromal phenomenology, or the nature of clinical course and outcome. Additionally, many questions regarding etiology, pathophysiology, and pathology have received less than adequate research attention.

Depression in old patients can be isolated or associated with dementia. In the first instance signs and symptoms sometimes mimic a demented state: disinterest, lack of initiative, mnesic complaints, slowing of thinking, learning difficulties. The EEG and the CT scan are useful in differential diagnosis, the value of the neuropsychological evaluation being compromised by lack of cooperation. In the second case the consequences of depression vary according to degree of severity of the dementia. In mild cases it can transitorily increase memory disturbances. In moderate and severe levels we see more regressive behavior. Sometimes we must wait for the therapeutic effects of antidepressant medication before we can establish the diagnosis with finality. The diagnosis of “pseudo-dementia” is only a provisional concept.

An intensive 10-day residential training program for dementia carers has previously been shown to be associated with increased patient survival at home and decreased psychological morbidity in carers (Brodaty & Gresham, 1989). Results from a further follow-up, about 39 months after entry into the trial, were even more impressive. Patients whose carers had trained in the program had much higher adjusted rates of survival at home (53% versus 13%) and, unexpectedly, fewer deaths (20% versus 41%) than those whose carers did not have training. Patients whose carers had delayed training achieved intermediate results (31% surviving at home and 21% dying). These results were achieved with an average saving of $A7,967 ($U.S.5975) per patient over the first 39 months.

Clinical and neuropathological examinations have shown that Alzheimer's disease is not a single entity. An early onset form with predominant parietal symptoms (type I) can be differentiated from a late onset form with mainly general cognitive symptoms and only mild parietal symptoms (type II). In CSF of patients with Alzheimer's disease type I there are signs of reduced blood-CSF barrier function and the metabolites of serotonin and dopamine are reduced in early stages, while in patients with type II there is often a diminished blood-CSF barrier function and in later stages there are reduced monoamine metabolites. Studies of membrane lipids of the brain have shown that myelin lipids are reduced in type II while gangliosides are markedly reduced in type I. Based on this finding a method has been developed for the assay of gangliosides in CSF. An increase of ganglioside GM1 seems to be a hallmark for Alzheimer's disease, type I.

The development of the concept of delirium spans nearly 2,500 years. Its core clinical features were recognized at least as early as the 16th century, while its management reflected a humane approach from the beginning of the modern era. In the 19th century delirium became linked with the concepts of disordered consciousness and confusion, but these two terms were also used in regard to certain functional mental disorders. The most important contribution in this century was the work of Engel, Romano, and associates, who postulated that the syndrome was due to reduction in brain metabolic rate, as reflected in slowing of the EEG background activity. These and other developments are discussed in this article. A list of proposed research priorities is included.

The Geriatric Depression Scale (GDS) is commonly used to measure depression in the elderly. However, there have been no reports of the underlying structure of the GDS. To this end, the GDS was administered to 326 community-dwelling elderly subjects, and the data were subjected to a factor analysis. A five-factor solution was selected and, after a varimax rotation, the factors that emerged could be described as: (1) sad mood, (2) lack of energy, (3) positive mood, (4) agitation, and (5) social withdrawal. This solution accounted for 42.9% of the variance. Knowledge of the factor structure should aid both clinicians and researchers in the interpretation of responses on the GDS.

“Delirium” is a reversible confusional state. It results from widespread but reversible interference with the function of cortical neurons, as documented by diffuse slowing on EEG and decreases in cerebral metabolic rate. Delirium can be due to impairments in neuronal metabolism, in neurotransmission (notably cholinergic), or in input from subcortical structures. Engel and Romano (1959) formulated delirium and dementia as the two poles of a spectrum of “cerebral insufficiency,” with delirium resulting from reversible functional impairment and dementia from irreversible anatomic damage. So many disorders can precipitate delirium that the differential diagnosis tests every facet of one's knowledge of medicine. With aging, both normative changes in the brain and the increasing incidence of brain diseases predispose to the development of delirium. The brain damage responsible for a dementia can sensitize to the development of a superimposed delirium.

The limitations of establishing neuropsychological diagnosis through psychological testing and psychiatric examination by clinicians are discussed, along with the need to define cases of illness in a standardized way for research. The GMS-HAS-AGECAT package is a standardized assessment of mental state and historical information about onset of illness, from which data are used in a computer-assisted method to derive clinically based diagnoses of the principal types of dementia, depression and other mental illness. Recording is made of co-morbid states and levels of diagnostic confidence. Agreement between psychiatrists on AECAT diagnoses ranges from kappa values of 0.76 to 0.88, and validity has now been tested further by outcome studies. A short description is given of the Medical Research Council, EURODEM, World Health Organization and Pan American Health Organization studies now using this method.

Rates of cognitive impairment in a representative population of the oldest old (aged 84 to 90) were examined using two indicators: The Global Deterioration Scale (GDS), and a Cognitive Rating (CR) derived from performance on five neuropsychological tests. Prevalence was estimated at 25.3%, using the GDS, and 30% with the CR. The overall degree of congruence between the measures was high, with most disagreements involving mildly impaired cases. The results indicate a high degree of convergence of clinical and neuropsychological indicators. The findings also confirm high rates of impairment among the oldest old.

Records of eight elderly patients identified as BPD by a geriatric team were analyzed for compliance with DIB-R and DSM-III-R criteria. A nonborderline control group was randomly selected and matched for age, gender and residence. Clinicians experienced in geriatric mental health performed retrospective chart reviews and found that not one clinically diagnosed BPD patient was identified by either instrument. Although there appear to be a number of constant features of BPD throughout life, this study delineated two major areas of change in BPD in late life.

While all delirious patients have clouding of consciousness (alteration of attention) and cognitive dysfunction, the level of alertness of different patients may range from stuporous to hyperalert. We, therefore, developed an analog scale to rate the alertness of delirious patients, and a separate scale to rate the severity of their clouding of consciousness. Based on these scales, patients were categorized overall as relatively “activated” (relatively alert despite clouding of consciousness), or “somnolent” (relatively stuporous along with clouding of consciousness). Cognitive function was estimated using the Mini-Mental Status Exam. Separate ratings were made of hallucinations, delusions, illusions, and agitated behavior. Activated and somnolent patients had similar ages, overall severity of delirium, and Mini-Mental Status Exam scores. Activated patients, however, were more likely to have hallucinations, delusions, and illusions than somnolent patients, and were more likely to have agitated behavior. Patients with hepatic encephalopathy were more likely to have somnolent delirium, while patients with alcohol withdrawal appeared more likely to have activated delirium. These data indicate that phenomenologic subtypes of delirium can be defined on the basis of level of alertness. These subtypes are validated in part by their differing associations with symptoms unrelated to alertness. These subtypes may have different pathophysiology, and thus, potentially different treatments.

Neuropsychology has an important role in a comprehensive psychogeriatric evaluation, especially in the assessment of dementia where the diagnosis is based on behavior. Current issues in the neuropsychology of aging and dementia in the oldest-old are discussed: the principal problem in the prevailing normative approach to discriminating between normal cognitive aging and pathology; the greater interindividual variability and, as a consequence, a need for subclassifications of individuals according to well-defined criteria; tests designed for cognitively impaired elderly and a contextual neuropsychological assessment procedure. Data from two ongoing Swedish studies of the oldest-old, illustrating some of these issues, are presented.

Positron Emission Tomography (PET) is a quantitative technique which can be used to measure regional values of cerebral metabolism, or uptake of radio-labeled tracers, in the living human. While structural scans (CT or MRI) may be normal in the degenerative dementias, or show generalized atrophy, functional imaging techniques allow differentiation of subtypes of dementias according to patterns of abnormal metabolism. This paper describes some of the variety of alterations in patterns of energy metabolism that may be observed in degenerative cognitive disorders and their correlations with clinical subtypes, together with an in vivo study of the dopaminergic system in subtypes of patients with dementia of the Alzheimer type (DAT).

We obtained season-of-birth data in 727 autopsy-confirmed cases of Alzheimer's Disease (AD) and compared these data with expected general population birth rates. There were no significant differences between quarterly birth rates in the AD group and expected quarterly birth rates. Edward's test for cyclical trends did not establish a peak period of birth in the AD sample. No significant differences between observed and expected quarterly birth rates were found when data were analyzed with regard to either family history of dementia or to gender. Edward's test for peak quarter was significant for AD females, however, with the peak period occurring early in the first quarter. These negative findings between observed and expected quarterly birth rates, based on the large number of autopsy-confirmed AD cases in this study, suggest that a season-of-birth effect in AD is highly unlikely.