Intellectual changes in aged twins

The Hollow Holiday: Christmas, a Time of Death in Appalachia

An inquiry was conducted into the question of the influence of Christmas and Easter on the occurrence of death. The authors hypothesized that dying might be postponed until after these two important events resulting in a significantly increased frequency of death after these holidays. Obituaries were read for 4 weeks before and 4 weeks after each holiday for 6 alternate years beginning in 1960 and ending in 1970. Chi square analyses were calculated for each week. The results indicated a significant peak 2 weeks after Christmas (p < .05). The Easter data did not corroborate the authors' hypothesis.

What Can We Learn From Longitudinal Studies of Adult Development?

This article distinguishes between normal and pathological aging, provides an interdisciplinary context, and then considers a sample case of cognitive aging. Developmental influences on cognition include the physiological infrastructure, genetic predispositions, and environmental influences. Different types of longitudinal studies are distinguished, and contrasting findings of cross-sectional and longitudinal are examined in the sample case of the Seattle Longitudinal Study. Also considered is the longitudinal context for intervention studies and the role of longitudinal family studies in assessing rate of aging and generational differences in rates of aging. Finally, attention is given to the role of longitudinal studies in the early detection of risk for dementia in advanced age.

Age at Onset, Survival Duration, and Cognitive Performance in Probable Alzheimer's Disease

The relative importance of age at onset, survival duration past testing, symptom duration, and education as predictors of cognitive performance was assessed in 50 patients with moderately severe dementia of the Alzheimer type. Survival past testing and duration of symptoms prior to assessment emerged as the strongest predictors of cognitive performance, and education effects were noted for several verbal tests. A robust association emerged between cognitive impairment and nearness to death. This association, first noted in studies of "normal" aging, requires further exploration. Age-at-onset effects, with poorer performance in early-onset disease, were observed only for a few measures.

Effect of repeated administration of a neuropsychological battery in the elderly

Our study explored the magnitude of practice effect in repeated administration of NP measures that tap different cognitive domains in normal elderly subjects (N = 122) between ages 57 and 85, who were evaluated over three annual testing probes. Results revealed that WAIS-R PIQ, serial recall of words, WMS visual memory, and memory for logical passages (immediate and delayed) are likely to improve on the retest due to practice effect in individuals below age 75, whereas test-retest changes in older people show a different pattern. Implications of age-specific changes on retest for differential diagnosis of dementia in clinical practice were considered.

Cognitive function and prediction of dementia in old age

Longitudinal changes in cognitive functioning were examined for a sample of aging twins, some of whom developed dementia while others did not. Individuals who were judged to be demented at a mean age of eighty-five years had achieved lower scores on most tests twenty years prior to diagnosis, and experienced greater declines in vocabulary and forward digit span over time, than those surviving to a comparable age without dementia. These trends were observed for individuals with mild, as well as moderate-to-severe, dementia and were unrelated to physical health status or premorbid activity patterns. It is suggested that dementing illness may develop very slowly, and that the likelihood of exhibiting clinically significant dementia may vary with premorbid intellectual level.

Cerebral metabolism, anatomy, and cognition in monozygotic twins discordant for dementia of the Alzheimer type

One pair of monozygotic twins discordant for dementia of the Alzheimer type (DAT) was studied using neuropsychological testing, quantitative x-ray computed tomography (QCT) and magnetic resonance imaging (MRI) of the brain. Cerebral glucose metabolism was measured using positron emission tomography (PET) and 2-[18-F]fluoro-2-deoxy-D-glucose (FDG). The affected twin had a seven year history of progressive cognitive impairment and was severely demented. Neuropsychological testing of the affected twin demonstrated marked deficits in all areas of cognitive function. The asymptomatic twin showed some impairment on tests of perceptual organisation and delayed recall. The affected twin had loss of gray matter and ventricular enlargement on QCT and MRI compared with healthy controls (p less than 0.05). He also had frontal and parietal lobe hypometabolism and increased asymmetry of metabolism on PET compared to both his twin and healthy age-matched controls (p less than 0.05). PET, QCT, and MRI distinguished changes in the twin with DAT compared with his brother and healthy controls. Although the subtle neuropsychological abnormalities of the asymptomatic twin may be signs of early DAT, they were not accompanied by any changes in regional cerebral metabolism or brain structure.

WAIS practice effects in clinical neuropsychology

A recent review (Matarazzo, Carmody, & Jacobs, 1980) has focused attention on the issue of WAIS practice effects in clinical practice. Available literature suggests that WAIS practice effects in may samples of patients with neuropsychological dysfunction are minimal. Data relevant to this hypothesis are reviewed. Practical guidelines for the interpretation of test-retest changes on the WAIS in neuropsychological assessment are proposed, and the importance of considering the impact of WAIS practice effects in neuropsychological research is addressed.

The terminal drop hypothesis: fact or artifact?

Findings from eight longitudinal investigations were reviewed in order to evaluate the terminal drop hypothesis. The concept of terminal drop was seen to be more useful when partitioned into its component parts: the relationship between the level of cognitive performance with survival and with distance from death, and the relationship between changes in cognitive performance and death. Health status and age at death emerged as important intervening variables in understanding the terminal drop concept.

Validation of the quick test for intelligence screening of the elderly

The composite Quick Test (Forms 1, 2, 3) and full WAIS were administered to 50 elderly Ss aged 60 to 100 yr. The purpose of this study was to validate the Quick Test for use with the elderly in order to determine whether the Quick Test could be satisfactorily substituted for the WAIS when intellectual screening is required for the elderly. For this sample, the WAIS Verbal IQ was higher than the Performance IQ in 84% of the cases. Correlation coefficients between the Quick Test and the WAIS Vocabulary, Verbal, Performance and Full Scale IQs ranged between .71 and .95 ( p < .001). These results strongly recommend the use of the Quick Test as a brief screening test to measure general intelligence in the elderly, particularly when administration of lengthy IQ tests is impractical or inefficient.

The twin-family method in psychiatric genetics illustrated from the investigations of Franz J. Kallmann

The present paper is aimed to celebrate Franz J. Kallmann's memory, by illustrating the twin-family method, which he developed. His phenomenal powers of organization are testified to by his extensive samples. Their representative nature has the built-in check of the ratio of MZ: DZ twins. He brought a refinement of his own to the existing methods of calculating expectancy from nett figures, that permits comparison of studies of varying age distributions relative to manifestation period. His investigative design allows not only for the standard global concordance comparisons between DZ and MZ twins as well as for those reared together and apart, but exploits the implications of the hitherto neglected comparison of the categories of sibs and DZ twins also. Further, his combined twin-family method comprehends in its extended range the powerful analytical tool of comparative figures for the series step-sibs, half-sibs, sibs, DZ twins and MZ twins (Kallmann and Sander, 1947; Kallmann, 1953). Kallmann (1954a, 1954b) has moreover given minute attention to controversies concerning legitimate inferences from twin studies, and has drawn attention to a point made by Darlington (1953), which is often overlooked by the best of geneticists. Discordance between MZ twins is not a measure merely of postnatal or even of prenatal environmental effects: it may also have a genetic component through the action of genes sensitive to cytoplasmic asymmetry.