title: Preclinical cognitive trajectories differ for Alzheimer's disease and vascular dementia.
abstract: We investigated differences between Alzheimer's disease (AD) and vascular dementia (VaD) from the appearance of the first cognitive symptoms, focusing on both time of onset and rate of accelerated decline for different cognitive functions before dementia diagnosis. Data from a longitudinal population-based study were used, including 914 participants (mean age = 82.0 years, SD = 5.0) tested with a cognitive battery (word recall and recognition, Block Design, category fluency, clock reading) on up to four occasions spanning 10 years. We fit a series of linear mixed effects models with a change point to the cognitive data, contrasting each dementia group to a control group. Significant age-related decline was observed for all five cognitive tasks. Relative to time of diagnosis, the preclinical AD persons deviated from the normal aging curve earlier (up to 9 years) compared to the preclinical VaD persons (up to 6 years). However, once the preclinical VaD persons started to decline, they deteriorated at a faster rate than the preclinical AD persons. The results have important implications for identifying the two dementia disorders at an early stage and for selecting cognitive tasks to evaluate treatment effects for persons at risk of developing AD and VaD.
authors.affiliation: Aging Research Center, Karolinska Institutet and Stockholm University, Stockholm, Sweden. erika.jonsson.laukka@ki.se
authors.forename: Erika J
authors.initials: EJ
authors.lastname: Laukka
authors.forename: Stuart W S
authors.initials: SW
authors.lastname: Macdonald
authors.forename: Laura
authors.initials: L
authors.lastname: Fratiglioni
authors.forename: Lars
authors.initials: L
authors.lastname: Bäckman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000150:complications*; D016009:Chi-Square Distribution; D003072:Cognition Disorders / Q000175:diagnosis* / Q000209:etiology*; D018672:Community Health Planning; D015140:Dementia, Vascular / Q000150:complications*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D061212:Memory, Episodic; D009483:Neuropsychological Tests; D013028:Space Perception; D014705:Verbal Behavior