Table 1.

Characteristics of women in the cognitive function substudy of the US-based nationwide Nurses’ Health Study by quintile of greenness [normalized difference vegetation index (NDVI), 1986–1994] at midlife ($N=\mathrm{16,962}$).

Total sample characteristics	Total sample ($n=\mathrm{16,962}$)	Quintile for greenness
		Q1 ($n=\mathrm{3,388}$) IQR: $<1.96$	Q2 ($n=\mathrm{3,400}$) IQR: 1.96–2.45	Q3 ($n=\mathrm{3,387}$) IQR: 2.46–2.81	Q4 ($n=\mathrm{3,394}$) IQR: 2.81–3.15	Q5 ($n=\mathrm{3,393}$) IQR: $>3.15$
Age, mean (y)	$74.23\pm 2.29$	$74.61\pm 2.34$	$74.37\pm 2.31$	$74.15\pm 2.24$	$74.06\pm 2.26$	$73.94\pm 2.25$
Participant’s education [$n$ (%)]
Registered nursing degree	13,166 (77.62)	2,490 (73.49)	2,713 (79.79)	2,703 (79.81)	2,661 (78.40)	2,599 (76.60)
Bachelor’s degree	2,802 (16.52)	688 (20.15)	507 (14.85)	479 (14.03)	525 (15.38)	603 (17.66)
Master’s or doctoral degree	994 (5.86)	210 (6.15)	180 (5.27)	205 (6.00)	208 (6.09)	191 (5.59)
Husband’s education [$n$ (%)]
Less than high school	272 (1.60)	46 (1.36)	62 (1.82)	31 (0.92)	59 (1.73)	74 (2.18)
Some high school	871 (5.14)	176 (5.16)	186 (5.45)	169 (4.95)	162 (4.75)	178 (5.21)
High school graduate	5,840 (34.43)	1,174 (34.39)	1,211 (35.47)	1,229 (36.00)	1,112 (32.57)	1,114 (32.63)
College graduate	3,762 (22.18)	723 (21.18)	732 (21.44)	747 (21.88)	820 (24.02)	740 (21.68)
Graduate school	2,733 (16.11)	549 (16.08)	473 (13.85)	522 (15.29)	589 (17.25)	600 (17.57)
Missing [$n$ (%)]	3,484	720	736	689	652	687
Marital status, married [$n$ (%)]
Yes	12,072 (71.17)	2,354 (68.95)	2,345 (68.69)	2,400 (70.30)	2,518 (73.76)	2,455 (71.91)
No	4,890 (28.83)	1,034 (30.51)	1,055 (31.02)	987 (29.14)	876 (25.81)	938 (27.64)
Low mental health score [$n$ (%)]
Yes	654 (3.86)	132 (3.87)	139 (4.07)	131 (3.84)	133 (3.90)	119 (3.49)
No	16,308 (96.14)	3,256 (96.10)	3,261 (95.91)	3,256 (96.13)	3,261 (96.08)	3,274 (96.49)
Antidepressant use [$n$ (%)]
Yes	968 (5.71)	201 (5.89)	216 (6.33)	175 (5.13)	201 (5.89)	175 (5.13)
No	15,994 (94.29)	3,187 (94.06)	3,184 (93.64)	3,212 (94.83)	3,193 (94.07)	3,218 (94.84)
Physical activity, mean (MET-h/wk)	$16.08\pm 16.20$	$15.95\pm 16.69$	$15.88\pm 16.33$	$15.44\pm 15.23$	$16.13\pm 16.1$	$17.02\pm 16.57$
BMI (${\mathrm{kg}/\mathrm{m}}^2$) [$n$ (%)]
$<22$	3,217 (18.96)	683 (20.17)	608 (17.88)	657 (19.39)	620 (18.26)	649 (19.13)
22–24.9	4,286 (25.27)	885 (26.14)	819 (24.09)	833 (24.58)	850 (25.04)	899 (26.50)
25–29.9	6,503 (38.34)	1,274 (37.63)	1,374 (40.41)	1,308 (38.60)	1,296 (38.17)	1,251 (36.87)
$\ge 30$	2,957 (17.43)	544 (16.07)	599 (17.62)	591 (17.44)	629 (18.53)	594 (17.51)
APOE-ɛ4 carriers (at least one allele) [$n$ (%)]
Yes	1,942 (11.45)	327 (9.58)	403 (11.80)	394 (11.54)	395 (11.57)	423 (12.39)
No	15,020 (88.55)	3,061 (90.34)	2,997 (88.14)	2,993 (88.36)	2,999 (88.36)	2,970 (87.53)
US Census tract median income	$\mathrm{43,787}\pm \mathrm{15,949}$	$\mathrm{42,731}\pm \mathrm{16,452}$	$\mathrm{40,855}\pm \mathrm{15,076}$	$\mathrm{42,533}\pm \mathrm{13,846}$	$\mathrm{45,131}\pm \mathrm{15,259}$	$\mathrm{47,718}\pm \mathrm{17,990}$
US Census tract home value	$\mathrm{125,122}\pm \mathrm{85,882}$	$\mathrm{159,422}\pm \mathrm{113,200}$	$\mathrm{108,961}\pm \mathrm{78,522}$	$\mathrm{106,758}\pm \mathrm{62,517}$	$\mathrm{116,947}\pm \mathrm{70,061}$	$\mathrm{133,738}\pm \mathrm{84,842}$
Population density ($n{/\mathrm{km}}^2$)	$\mathrm{1,302.87}\pm \mathrm{2,790.52}$	$\mathrm{2,748}\pm \mathrm{5,320}$	$\mathrm{1,497}\pm \mathrm{2,053}$	$\mathrm{1,100}\pm \mathrm{1,021}$	$790\pm \mathrm{1,374}$	$392\pm 524$
Average global cognition composite score over follow-up	$-0.02\pm 0.59$	$-0.07\pm 0.61$	$-0.06\pm 0.6$	$-0.01\pm 0.58$	$0\pm 0.58$	$0.02\pm 0.57$

Note: Values are expressed as $\text{mean}\pm \text{SD}$, unless otherwise specified. Quintiles of greenness are based on cumulative average summer NDVI value at a $270\text{-m}$ buffer. APOE, apolipoprotein E; BMI, body mass index; MET, metabolic equivalent of task; Q, quintile; SD, standard deviation.