Alzheimer's Disease in the National Academy of Sciences Registry of Aging Twin Veterans

Abstract

The (US) National Academy of Sciences Registry of aging twin veterans contains 15,924 pairs of white male twins born between 1917 and 1927. About 8,000 pairs are living today. In preparation for a study of Alzheimer's disease (AD) in this Registry, we investigated 829 members of pairs living in North and South Carolina, Virginia, in the District of Columbia, and Maryland. A brief telephone interview for cognitive symptoms was administered to 678 (91.4%) of 742 subjects located. Cognitive dysfunction was identified initially in 124 individuals (18.3%), whose clinical histories were then obtained over the telephone. Results suggested that 108 subjects did not have AD. Ten (62.5%) of the remaining 16 subjects underwent diagnostic evaluation for dementia. One had cerebrovascular disease with coincident depression. Two others with probable AD were a monozygotic (MZ) pair. The remaining 7 subjects had possible AD or a mild but progressive cognitive disorder suggestive of early AD. Upon subsequent examination, 3 of 4 MZ co-twins showed significant symptoms that had not been detected during screening procedures. None of 3 dizygotic co-twin showed any significant abnormality. These results suggest: (1) that a combination of mailed information, telephone interviews, and clinical examination provides a feasible means of detecting AD in the Registry, (2) that about 150 pairs with presumptive AD in 1 or both subjects will be identified in a full study of the Registry; (3) that concordance for AD in MZ pairs may exceed prior estimates, but (4) that such rates of concordance are apparent only upon detailed evaluation of apparently normal co-twins as well as their impaired brothers. Longitudinal observation of pairs with apparently affected individuals will be required for definitive conclusions.

Alzheimer's Disease in the NAS-NRC Registry of Aging Twin Veterans

“…Details of the assessment proto col, which included the CERAD battery, have been described [3]. No subject died or refused to participate in the longitudinal observa tions.…”

“…Neuropsychological tests included an MMSE of 26, BNT score of 13, and deficits in memory and in the Trailmaking test. He was placed in the category o f'mild/ambiguous' change (our 1990 paper [3] erroneously reported his category as pos-siblc AD in its tabic 1). but laboratory testing was deferred pending additional observation.…”

“…of the eastern United States [3]. Our main aim was the development of a method for AD screening using tele phone interviews followed by in-person clinical assess ment.…”

Duke Twins Study of Memory in Aging in the NAS-NRC Twin Registry

“…For the diagnosis of CIND and its subtypes, we used standardized criteria that we have developed for all of our studies. (Breitner et al, 1994b;Breitner et al, 1999;Langa et al, 2005) Age of onset of dementia was assigned based on the age at which the person unambiguously met criteria for dementia. For the participants with suspected dementia who did not complete a clinical assessment, we reviewed all available information including medical records, DQ information, and autopsy results to assign a diagnosis.…”

The Memory and Aging Telephone Screen: Development and preliminary validation

“…Several modified (TICS-m) versions have emerged, which notably include a delayed recall task [32][33][34], and more recently, two parallel versions of the word list memory task [35]. Although the TICS revision includes items thought to be more sensitive to early cognitive impairment (e.g., delayed recall), it has yet to be utilized extensively in preclinical populations and may have poor positive predictive value in mildly impaired or "ambiguous" cases [34].…”