Table 2.

Linear Mixed Regression Models Predicting IRT-Based CASI scores^a

	Analysis 1 (Examination 1 language)	Analysis 2 (Examination 5 language)
	2,520 participants	2,029 participants
Covariate	Coefficient (95% CI)	Coefficient (95% CI)
Examination 1 or 5  language use
Spoke but did not read Japanese	0 (reference)	0 (reference)
Neither spoke nor read Japanese	1.94 (−0.95 to 4.84)	−2.31 (−4.90 to 0.28)
Both spoke and read Japanese	0.02 (−2.83 to 2.88)	−2.15 (−6.73 to 2.43)
Age	−12.24 (−17.53 to −6.95)	−12.66 (−18.19 to −7.12)
Age × Examination 1 or 5 language
Spoke but did not read Japanese	0 (reference)	0 (reference)
Neither spoke nor read Japanese	−1.54 (−7.76 to 4.69)	3.17 (−2.27 to 8.62)
Both spoke and read Japanese	−1.24 (−6.93 to 4.45)	1.97 (−6.72 to 10.67)
Age2	−1.96 (−3.60 to −0.33)	−1.11 (−30.41 to 4.26)
Age2 × Examination 1 or 5 language
Spoke but did not read Japanese	0 (reference)	0 (reference)
Neither spoke nor read Japanese	1.07 (−2.18 to 4.33)	−1.74 (−4.53 to 1.05)
Both spoke and read Japanese	0.77 (−1.99 to 3.54)	−0.59 (−4.67 to 3.49)

Note: CASI = Cognitive Abilities Screening Instrument; CI = confidence interval; IRT = item response theory.

^aModels were adjusted by including random effects for age and age squared and fixed effects for exposure category, age at Honolulu-Asia Aging Study (HAAS) Examination 4, education, education squared, income category, smoking status, apolipoprotein E ϵ4, and the number of tests taken. CASI scores are IRT based. Age effects are for 10 years, centered at age 70. IRT scores were calibrated such that the mean of nondemented HAAS participants at baseline was 100 and the standard deviation was 15, similar to IQ scores. Over a decade, a man in the reference group is predicted to decline 12.24 points (almost 1 SD). The decline for men in the other two groups was not statistically different than this value (CIs for both the linear and quadratic interaction terms with exposure status include the null value of 0).