TABLE 1—

Sample Characteristics Among Participants, by Social Integration Quartile: Health and Retirement Study, United States, 1998

	All Participants (N = 16 638)		Participants With High Social Integration (Highest Quartile)		Participants With Low Social Integration (Lowest 3 Quartiles)
	Mean (SE) or %	No.	Mean (SE) or %	No.	Mean (SE) or %	No.
Age, y	64.5 (0.08)	16 638	59.3 (0.11)	3496	65.9 (0.09)	13 142
Women	57.6	16 638	50.2	3496	59.7	13 142
Education, y	12.6 (0.02)	16 638	13.4 (0.04)	3496	12.3 (0.03)	13 142
White	88.4	16 638	91.4	3496	87.5	13 142
CES-D score	1.5 (0.01)	16 638	1.1 (0.03)	3496	1.6 (0.02)	13 142
Health conditions	1.5 (0.01)	16 638	1.2 (0.02)	3496	1.6 (0.01)	13 142
Memory score at each wave
1998	11.0 (0.03)	16 638	11.9 (0.05)	3496	10.7 (0.03)	13 142
2000	10.4 (0.03)	14 614	11.3 (0.06)	3226	10.1 (0.03)	11 388
2002	10.2 (0.03)	13 341	11.2 (0.06)	3053	9.9 (0.04)	10 288
2004	10.0 (0.03)	12 335	10.9 (0.06)	2914	9.7 (0.04)	9421

Note. CES-D = Center for Epidemiological Studies Depression Scale. Means, standard errors, and percentage values were weighted to account for the complex sampling design of the Health and Retirement Study. All differences between participants with high and low social integration were statistically significant (P < .01).