Table 1.

Baseline characteristics of participants

Characteristics	Total (n, %)	Annual average NDVI (mean±SD)	MMSE scores (mean±SD)
	38 327	0.40±0.15	21±9.72
Age (years) (mean±SD)	88±11.45	/	/
Age group (years)
65–79	8528 (22.25)	0.38±0.15	27±4.11
80–89	10 161 (26.51)	0.40±0.14	24±7.14
90–99	10 418 (27.18)	0.40±0.15	19±9.80
≥100	9220 (24.06)	0.40±0.15	13±10.31
Gender
Males	15 747 (41.09)	0.39±0.15	24±8.37
Females	22 580 (58.91)	0.40±0.15	19±10.04
Ethnicity
Han Chinese	36 156 (94.34)	0.39±0.15	21±9.76
Ethnic minorities	2171 (5.66)	0.46±0.13	21±9.02
Marital status
Married and living with their spouse	10 287 (26.84)	0.38±0.15	26±6.52
Not married	28 040 (73.16)	0.40±0.15	19±10.08
Residence
Urban area	9076 (23.68)	0.24±0.13	21±9.87
Rural area	29 251 (76.32)	0.45±0.12	20±9.66
Occupation
Professional work	2659 (6.94)	0.31±0.16	26±6.92
Non-professional work	35 668 (93.06)	0.40±0.15	20±9.77
Education
Formal education	13 347 (34.82)	0.37±0.16	25±7.68
No formal education	24 980 (65.18)	0.41±0.14	18±9.96
Financial support
Financial independence	9142 (23.85)	0.33±0.16	26±6.86
Financial dependence	29 185 (76.15)	0.42±0.14	19±9.96
Social and leisure activity index (mean±SD)	2.07±1.55	/	/
Smoking status
Yes	6804 (17.75)	0.41±0.14	24±8.16
No	31 523 (82.25)	0.40±0.15	20±9.91
Alcohol consumption
Yes	7383 (19.26)	0.41±0.14	23±8.87
No	30 944 (80.74)	0.39±0.15	20±9.85
Physical activity
Yes	10 923 (28.50)	0.36±0.15	24±7.38
No	27 404 (71.50)	0.41±0.14	19±10.11
Geographic region
Central China	5580 (14.56)	0.44±0.12	20±9.84
Eastern China	15 491 (40.42)	0.40±0.16	21±9.60
Northeastern China	2922 (7.62)	0.28±0.11	20±10.58
Northern China	1922 (5.01)	0.26±0.11	21±9.81
Northwestern China	512 (1.34)	0.37±0.14	21±8.53
Southern China	6931 (18.08)	0.44±0.13	21±9.21
Southwestern China	4969 (12.96)	0.40±0.13	20±10.06

MMSE, Mini-Mental State Examination; NDVI, Normalised Difference Vegetation Index.