title: Aging and cognition: methodological differences in outcome.
abstract: A series of longitudinal and cross sectional studies, collected as part of the Seattle Study, were reanalyzed. A longitudinal sequential analysis (N = 232), wherein subjects were measured every seven years for four time periods, was completed on the Primary Mental Abilities test. Cohort differences were at least as strong as age differences; cohorts were generally relatively stable over the measured periods, showing little cognitive decline. A cross-sectional sequential analysis (N = 2813) was completed for the same time periods; decline with age was more evident than with the longitudinal sequential analysis. A cross-sectional analysis for the fourth time period (N = 611) showed the most marked decline of all. Interpretation of outcome was highly dependent on the analysis used.
authors.affiliation: University of North Dakota, Grand Forks, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Williams
authors.forename: M G
authors.initials: MG
authors.lastname: Klug
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000523:psychology*; D003071:Cognition; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007807:Language Tests; D008137:Longitudinal Studies; D008297:Male; D008433:Mathematics; D008875:Middle Aged; D008960:Models, Psychological; D013028:Space Perception; D013850:Thinking