Table 1.

Baseline Characteristics and Dementia Incidence of the Entire Study Population and by Social Network Group

Characteristics	Total Cohort (N = 2636)	Social Network Strength		p Value
		Weak (N = 1341)	Strong (N = 1295)
Baseline
Age (years)	76.7 ± 3.9	77.3 ± 4.1	76.2 ± 3.6	<.0001
Education (years)	11.0 ± 3.1	10.7 ± 3.0	11.2 ± 3.1	<.0001
Not married (%)a	15.9	23.4	8.1	<.0001
With APOE ɛ4 allele (%)b	18.5	17.4	19.6	.149
Prevalent stroke (%)	2.47	2.76	2.16	.323
CES-D score	3.54 ± 3.51	3.87 ± 3.57	3.20 ± 3.40	<.0001
Depressive symptoms (CES-D ≥ 9; %)c	8.7	10.2	7.1	.0053
CASI score	88.2 ± 6.0	87.6 ± 6.1	88.7 ± 5.8	<.0001
Cognitively impaired (CASI score < 74; %)	0	0	0	—
Total cholesterol (mg/dL)d	193.01 ± 31.94	193.56 ± 32.19	192.48 ± 31.69	.391
Fasting glucose (mg/dL)e	113.36 ± 27.76	112.63 ± 26.07	114.12 ± 29.38	.171
Diabetes mellitus (%)f	29	30	27	.038
Hypertension (%)f	75.0	76.0	74.8	.489
Smoking (pack-years)g	25.8	26.2 ± 34.3	25.4 ± 34.4	.578
During follow-up
Incident ACD (N, %)	173 (6.6)	110 (8.2)	63 (4.9)	.0005
Incident AD (N, %)	104 (4.0)	68 (5.1)	36 (2.8)	.0025
Incident VaD (N, %)	38 (1.4)	24 (1.8)	14 (1.1)	.1270

Notes: Values are given as mean ± SD or median (range) for continuous variables, and as percentages for categorical variables. p Values were computed by t test or chi-square test, as appropriate. CES-D Scale = Center for Epidemiologic Studies Depression (CES-D) 11-item Scale; CASI = Cognitive Abilities Screening Instrument; ACD = all-cause dementia; AD = Alzheimer’s disease; VaD = vascular dementia; SD = standard deviation. The weak social network group is defined by Lubben social network scale (LSNS) score ≤29, and strong social networks by LSNS score >29.

^a N = 2635.

^b N = 2583.

^c N = 2631 (valid CES-D, with < 3 missing answers).

^d N = 2603.

^e N = 2602.

^f N = 2604.

^g N = 2596.