Limited Health Literacy and Decline in Executive Function in Older Adults

Figures & data

Table 1. Demographic information

	Total (N = 226), n (%)	Limited health literacy (n = 84), n (%)	Higher health literacy (n = 142), n (%)	Chi-square statistic (df)	p*
Randomization				0.143 (1)	.705
Control	114 (50.4)	41 (48.8)	73 (51.4)
Intervention	112 (49.6)	43 (51.2)	69 (48.6)
Age (years)				1.132 (3)	.769
65–69	105 (46.5)	39 (46.4)	66 (46.5)
70–74	57 (25.2)	24 (28.6)	33 (23.2)
75–79	45 (19.9)	15 (17.9)	30 (21.1)
80+	19 (8.4)	6 (7.1)	13 (9.2)
Sex				0.108 (1)	.742
Female	143 (63.3)	52 (61.9)	91 (64.1)
Race				45.538 (2)	<.001
Black	142 (62.8)	76 (90.5)	66 (46.5)
White	67 (29.6)	4 (4.8)	63 (44.4)
Other	17 (7.5)	4 (4.8)	13 (9.2)
Education				46.530 (2)	<.001
Less than high school	48 (21.2)	34 (40.5)	14 (9.9)
High school	68 (30.1)	32 (38.1)	36 (25.4)
More than high school	110 (48.7)	18 (21.4)	92 (64.8)
Number of comorbidities ^a				8.222 (2)	.016
None	107 (47.3)	30 (35.7)	77 (54.2)
1	63 (27.9)	26 (31.0)	37 (26.1)
2+	56 (24.8)	28 (33.3)	28 (19.7)
PHQ-9 score				4.928 (2)	.085
Minimal (1–4)	186 (82.3)	63 (75.0)	123 (86.6)
Mild (5–9)	30 (13.3)	16 (19.0)	14 (9.9)
Moderate (10–14)	10 (4.4)	5 (6.0)	5 (3.5)

Table 2. Executive function at baseline and 12-month follow-up, by health literacy

Time	Limited health literacy (n = 84)	Higher health literacy (n = 142)	t test statistic (df)	p ^a
Delta Trail Making Test (seconds), ^b M (SD)
Baseline	159.2 (68.2)	84.5 (59.0)	8.62 (222)	<.001
12 months	178.1 (58.6)	93.6 (67.1)	9.50 (222)	<.001
Change ^e	18.8 (65.5)	9.1 (52.3)	1.14 (136)	.258
FAS (average number), ^c M(SD)
Baseline	22.0 (10.5)	34.3 (12.9)	−7.71 (202)	<.001
12 months	22.2 (11.0)	35.3 (13.4)	−7.49 (222)	<.001
Change ^e	0.02 (9.4)	1.1 (9.2)	−0.83 (221)	.407
Category Fluency (average number), ^d M (SD)
Baseline	24.1 (6.0)	29.8 (7.9)	−6.04 (211)	<.001
12 months	23.7 (6.8)	29.5 (8.2)	−5.48 (223)	<.001
Change ^e	−0.5 (5.2)	−0.2 (5.5)	−0.40 (223)	.686

Table 3. Linear regression for change in executive function from baseline to 12 months

Variable	Change in delta TMT^a (seconds)			Change in FAS ^b (average number)			Change in category fluency ^c (average number)
	β (95% CI) ^d	F	p ^e	β (95% CI) ^d	F	p ^e	β (95% CI) ^d	F	p ^e
Health literacy
Low	23.8 (5.3, 42.2)	6.46 (1, 204)	.012	−1.8 (−4.8, 1.2)	1.44 (1, 205)	.232	−0.4 (−2.2, 1.3)	0.22 (1, 207)	.641
High (ref)
Baseline scores	−0.5 (−0.6, −0.3)	59.61 (1, 204)	<.001	−0.3 (−0.4, −0.2)	26.90 (1, 205)	<.001	−0.2 (−0.4, −0.1)	21.26 (1, 207)	<.001
Randomization
Intervention	9.2 (−4.7, 23.1)	1.71 (1, 204)	.193	0.2 (−2.1, 2.6)	0.04 (1, 205)	.841	−0.5 (−1.9, 0.9)	0.46 (1, 207)	.500
Control (ref)
Clinic^¶
Clinic 2	−12.2 (−32.5, 8.1)	2.43 (2, 204)	.090	−2.1 (−5.5, 1.2)	9.20 (2, 205)	<.001	0.6 (−1.4, 2.6)	0.80 (2, 207)	.449
Clinic 3	−22.8 (−48.0, 2.4)			5.4 (1.2, 9.6)			1.3 (1.2, 3.9)
Clinic 1 (ref)
Age (years)
70–74	−1.2 (−23.9, 21.6)	0.50 (3, 204)	.685	0.4 (−3.5, 4.2)	1.46 (3, 205)	.227	−0.7 (−2.9, 1.6)	2.57 (3, 207)	.055
75–79	10.2 (−14.6, 35.0)			0.3 (−3.9, 4.4)			0.5 (−2.0, 2.9)
80+	0.2 (−35.9, 36.3)			−4.3 (−10.3, 1.8)			−3.4 (−6.9, 0.2)
65–69 (ref)
Sex
Female	−15.4 (−30.2, −0.6)	4.21 (1, 204)	.042	1.1 (−1.4, 3.5)	0.71 (1, 205)	.400	0.3 (−1.2, 1.8)	0.13 (1, 207)	.714
Race
Black	15.6 (−7.3, 38.7)	1.30 (2, 204)	.274	−4.9 (−8.7, −1.0)	4.53 (2, 205)	.012	−1.2 (−3.6, 1.1)	0.81 (2, 207)	.446
Other	7.1 (−28.8, 42.9)			−3.2 (−9.0, 2.6)			−1.2 (−4.7, 2.3)
White (ref)
Education
Less than high school	26.0 (1.6, 50.4)	3.17 (2, 204)	.044	−2.7 (−6.7, 1.3)	1.49 (2, 205)	.229	−1.7 (−4.1, 0.7)	1.50 (2, 207)	.226
High school	10.7 (−10.0, 31.4)			−0.1 (−3.4, 3.3)			−0.3 (−2.3, 1.8)
More than high school (ref)
Number of Comorbidities^g
1	3.9 (−15.6,23.5)	1.42 (2, 204)	.244	−0.2 (−3.4, 3.1)	0.30 (2, 205)	.743	−1.2 (−3.2, 0.8)	1.48 (2, 207)	.231
2+	14.9 (−6.0,35.9)			1.0 (−2.5, 4.5)			−1.2 (−3.3, 0.9)
0 (ref)
PHQ-9^h
Mild (5–9)	−9.4 (−34.3,15.5)	0.43 (2, 204)	.653	0.3 (−3.9, 4.6)	0.81 (2, 205)	.447	0.7 (−1.9, 3.1)	2.10 (2, 207)	.125
Moderate (10–14)	2.7 (−40.1, 45.5)			3.6 (−3.1, 10.3)			3.5 (−0.6, 7.5)
Minimal (1–4) (ref)
R ^2	0.28			0.24			0.17
F	4.77 (17, 204)			3.71 (17, 205)			2.48 (17, 207)
P	<.001			<.001			.001