Table 4.

Change-Point Models Estimating Preterminal and Terminal Cognitive Change

Variable	Intercept, γ00	Change point	Slope, γ10/γ20	SE	t
Semantic verification	2,985.33	9.5	20.42	30.91	0.66
			99.54	40.49	2.46*
Sentence construction	4.78	3.5	−0.05	0.01	−2.94**
			0.06	0.07	0.91
Word recall	17.09	6.8	−0.27	0.04	−7.24**
			−0.04	0.09	−0.51
Fact recall	20.15	8.2	−0.43	0.05	−8.37**
			−0.11	0.09	−1.11
Vocabulary	43.83	6.4	−0.13	0.06	−2.19*
			−0.07	0.12	−0.62

Notes: γ₀₀ = cognitive performance centered at 70 years of age and the specified change-point years prior to death; change point = number of years prior to death where the inflection between preterminal (age-based) and terminal (time-to-death) slopes yields the best model fit based on the highest likelihood value; γ₁₀ = average linear rate of cognitive change per additional year of age (centered at 70 years); γ₂₀ = average linear rate of cognitive change per year closer to death following the change point; t = t ratio. Intercept, slope, and change-point coefficients reflect response latencies in milliseconds for semantic verification, values on a 0–6 scale for sentence construction, values out of 30, 40, and 54, respectively, for word recall, fact recall, and vocabulary. Age at death, centered at 75 years of age, was entered as a covariate for all models.

^*p < .05; **p < .01.