Table 1.

Means (and standard deviations) of demographic characteristics of the participants by age decade

Age Decade	N1 / N2	T1 Age	Prop. Female	T1 Health	Years of Education	T1 MMSE	T2-T1 Interval
20's	850 / 245	23.2 (3.2)	.59	2.0 (0.9)	14.7 (2.1)	28.8 (1.6)	3.1 (1.9)
30's	461 / 193	34.3 (2.8)	.70	2.1 (0.8)	15.7 (2.8)	28.5 (1.8)	3.1 (2.0)
40's	743 / 392	45.0 (2.9)	.71	2.1 (0.9)	15.3 (2.7)	28.5 (1.8)	3.3 (1.9)
50's	1104 / 596	54.4 (2.8)	.71	2.2 (0.9)	15.7 (2.6)	28.4 (1.9)	3.0 (1.6)
60's	842 / 429	64.1 (2.8)	.65	2.1 (0.9)	16.4 (2.8)	28.5 (1.9)	2.9 (1.4)
70's	539 / 301	74.2 (2.9)	.58	2.4 (0.9)	15.9 (2.9)	28.1 (1.9)	2.7 (1.2)
80's	235 / 101	83.1 (2.5)	.51	2.6 (0.8)	16.1 (3.1)	27.2 (2.5)	2.5 (1.1)
All	4774 / 2257	50.8 (18.0)	.64	2.2 (0.9)	15.6 (2.7)	28.4 (1.9)	3.0 (1.6)

Note: Health is a self-rating on a scale from 1 for excellent to 5 for poor. MMSE is the Mini Mental State Exam (Folstein et al., 1975). N1 and N2 refer to the number of participants in the cross-sectional and longitudinal samples. The T2-T1 interval is in years.