Figure 3.

Model-predicted trajectories of cognitive function for representative Japanese-American men from the Honolulu-Asia Aging Study. We used the regression results shown from the selection model (left column of Table 4) to determine item response theory (IRT)-based CASI scores for men entering the study at age 70 (top three solid lines) and at age 80 (bottom three dashed lines). All six groups had 10 years of education, were nonsmokers, had an income from $20,000 to 29,999, and had no apolipoprotein E ϵ4 alleles. We used these values in Excel to obtain model-predicted IRT CASI scores at baseline and then 10 years later (when men in the first group would be 80 and men in the second group would be 90). Men who neither spoke nor read Japanese (depicted in black) had a modestly higher cognitive functioning level at baseline compared with both the group that spoke but did not read Japanese (depicted in red) and the group that both spoke and read Japanese (depicted in blue). This “advantage” of neither speaking nor reading Japanese was maintained consistently across a decade. *CASI = Cognitive Abilities Screening Instrument. The IRT scores were scaled such that the mean score for nondemented individuals at baseline in the Honolulu-Asia Aging Study had a mean of 100 and a standard deviation of 15. The representative men depicted here are predicted to decline roughly a full standard deviation over a decade. This anticipated decline is not affected by whether the men spoke or read Japanese.