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Joint modelling of survival and cognitive decline in the Australian Longitudinal Study of Ageing
Author(s) -
Graham Petra L.,
Ryan Louise M.,
Luszcz Mary A.
Publication year - 2011
Publication title -
journal of the royal statistical society: series c (applied statistics)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.205
H-Index - 72
eISSN - 1467-9876
pISSN - 0035-9254
DOI - 10.1111/j.1467-9876.2010.00737.x
Subject(s) - dropout (neural networks) , tobit model , cognition , cohort , cognitive decline , ceiling effect , gerontology , ageing , demography , psychology , econometrics , medicine , statistics , computer science , mathematics , dementia , psychiatry , sociology , machine learning , disease , pathology , alternative medicine
Summary. The paper describes the use of a longitudinal tobit model to characterize cognitive decline over a 13‐year period in a cohort of 2087 elderly Australians. Use of a tobit formulation allows for the so‐called ‘ceiling effect’ wherein many subjects achieve perfect test scores. A Bayesian hierarchical joint model is presented that allows for random subject‐specific intercepts and slopes, as well as for informative dropout. Results suggest several potential areas of intervention. For example, there is a clear dose–response effect of exercise whereby increasing levels of exercise are associated with higher cognitive scores.