Table 2.

Association between social relationships and serum BDNF levels (N = 3294)

Independent variable∗	Above versus below median BDNF
	No. (%)	Odds ratio (95% CI)	P value
Social isolation†	116 (4)	0.69 (0.47–1.00)	.05
Support items‡
Listening	2817 (86)	1.09 (0.90–1.33)	.38
Advice	2607 (80)	1.05 (0.89–1.25)	.56
Affection	2854 (87)	1.18 (0.96–1.46)	.12
Emotional	2804 (86)	1.27 (1.04–1.54)	.02

Abbreviations: BDNF, brain-derived neurotrophic factor; CI, confidence interval.

^∗Adjusted for age and sex.

^†Not married, fewer than six friends or relatives, and no membership in either church or community groups.

^‡Separate models for each dimension of social support based on frequency provided (i.e., most or all of the time versus some, little, or none of the time): Listening, “Can you count on anyone to listen to you when you need to talk?”; Advice, “Is there someone available to give you good advice about a problem?”; Affection, “Is there someone available to you who shows you love and affection?”; and Emotional, “Can you count on anyone to provide you with emotional support?”