Handbook of Neuropsychology and Aging

Summary Specific age-related hypotheses are tested in population-based longitudinal studies. At specific time intervals, both the outcomes of interest and time-varying covariates are measured. When participants are approached for follow-up, some participants do not provide data. Investigations may show that many have died before the time of follow-up while others refused to participate. Some of these non-participants do not provide data at later follow-ups. Few statistical methods for missing data distinguish between “non-participation” and “death” among study participants. The augmented inverse probability-weighted estimators are most commonly used in marginal structure models when data are missing at random. Treating non-participation and death as the same, however, may lead to biased estimates and invalid inferences. To overcome this limitation, a multiple inverse probability-weighted approach is presented to account for two types of missing data, non-participation and death, when using a marginal mean model. Under certain conditions, the multiple weighted estimators are consistent and asymptotically normal. Simulation studies will be used to study the finite sample efficiency of the multiple weighted estimators. The proposed method will be applied to study the risk factors associated with the cognitive decline among the aging adults, using data from the Chicago Health and Aging Project (CHAP).

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Beyond memory impairment: cognitive changes in Alzheimer's disease

Helmes

Østbye

2002

Archives of Clinical Neuropsychology

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In addition to memory impairment, deficits in other cognitive processes are common in the advanced stages of Alzheimer's disease (AD). The diagnosis of AD does not consider the relative prevalence of deficits in cognitive areas other than memory. We report on the prevalence of aphasia, apraxia, and other cognitive changes in individuals from a large representative sample of elderly Canadians. The proportion of these symptoms and the relevant neuropsychological test performance were compared in a group of 749 people over 65 years in age with AD and a control group of 563 people without cognitive impairment. Agnosia was less common in both groups than were deficits in complex visuomotor tasks, abstract thinking, aphasia, and constructional defects. The occurrence of all symptoms increased, and levels of performance on relevant neuropsychological tests decreased, with severity of Alzheimer disease. The tests did not, however, distinguish between possible and probable AD. Both these diagnostic groups showed similar levels of performance, which suggests that this distinction is not clinically meaningful.

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Handbook of Neuropsychology and Aging

Cited by 23 publications

References 1,052 publications

Depressive symptoms among the medically hospitalized older individuals — a 1‐year follow‐up study

Depressive symptoms among the medically hospitalized older individuals — a 1‐year follow‐up study

Joint modeling of missing data due to non‐participation and death in longitudinal aging studies

Beyond memory impairment: cognitive changes in Alzheimer's disease

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