Lack of associations between modifiable risk factors and dementia in the very old: findings from the Cambridge City over-75s cohort study

Figures & data

Figure 1. CC75C study design.

Figure 2. Survey 4 cases of incident severe cognitive impairment or dementia.

Table 1. Characteristics of Survey 4 participants (excluding prevalent cases and participants with data missing for more than two risk/protective factors) by outcome status.

	Incident dementia status (n = 323)^a			Incident severe cognitive impairment status (n = 318)^b			Incident dementia/severe cognitive impairment status (n = 278)^c
Variable	Yes, n = 76	No, n = 247	p-Value	Yes, n = 44	No, n = 274	p-Value	Yes, n = 75	No, n = 203	p-Value
Age, mean (SD)	87.7 (2.7)	88.1 (3.4)	0.362	87.8 (3.1)	87.7 (3.1)	0.987	87.6 (3.0)	87.9 (3.2)	0.573
Age at death, mean (SD)	94.2 (3.8)	93.0 (4.4)	0.025	96.7 (3.9)	92.5 (4.1)	0.000	95.1 (3.9)	92.5 (4.3)	0.000
Female, n (%)	60 (79.0)	170 (68.8)	0.088	37 (84.1)	179 (65.3)	0.013	59 (78.7)	130 (64.0)	0.020
Educational level, n (%)			0.478			0.346			0.694
Left school aged less than 15 years	43 (56.6)	151 (61.1)		29 (65.9)	160 (58.4)		42 (56.0)	119 (58.6)
Left school aged 15 years old or more	33 (43.4)	96 (38.9)		15 (34.1)	114 (41.6)		33 (44.0)	84 (41.4)
Marital status, n (%)			0.342			0.344			0.326
Married	15 (19.7)	51 (20.7)		7 (15.9)	60 (21.9)		15 (20.0)	46 (22.7)
Widowed	52 (68.4)	165 (66.8)		31 (70.5)	182 (66.4)		53 (70.7)	131 (64.5)
Separated/divorced	–	9 (3.6)		–	9 (3.3)		–	8 (3.9)
Never married	9 (11.8)	22 (8.9)		6 (13.6)	23 (8.4)		7 (9.3)	18 (8.9)
Place of residence, n (%)			0.828			0.297			0.567
House/flat/granny flat	60 (79.0)	192 (77.7)		34 (77.3)	215 (78.5)		60 (80.0)	162 (79.8)
Warden controlled	8 (10.5)	23 (9.3)		7 (15.9)	26 (9.5)		9 (12.0)	18 (8.9)
Long-term care institute	8 (10.5)	32 (13.0)		3 (6.8)	33 (12.0)		6 (8.0)	23 (11.3)
Social class, n (%)			0.980			0.810			0.905
Non-manual skills	35 (47.3)	115 (47.1)		21 (48.8)	127 (46.9)		36 (49.3)	97 (48.5)
Manual skills	39 (52.7)	129 (52.9)		22 (51.2)	144 (53.1)		37 (50.7)	103 (51.5)
Disabilities in ADLs or IADLs, n (%)			0.032			0.054			0.004
No disability	35 (46.7)	80 (32.4)		23 (52.3)	92 (33.7)		38 (51.4)	65 (32.0)
Disability in IADLs only	21 (28.0)	67 (27.1)		10 (22.7)	76 (27.8)		20 (27.0)	56 (27.6)
Disability in both ADLs and IADLs	19 (25.3)	100 (40.5)		11 (25.0)	105 (38.5)		16 (21.6)	82 (40.4)
MMSE score at Survey 4, mean (SD)^d	21.72 (6.7)	24.05 (5.4)	0.002	23.4 (3.5)	25.3 (3.2)	0.001	24.3 (3.5)	25.6 (3.1)	0.003
Number of available risk/protective factors, n (%)^e			0.582			0.256			0.222
<7 risk/protective factors	3 (4.0)	16 (6.5)		–	16 (5.8)		1 (1.3)	13 (6.4)
7 risk/protective factors	13 (17.1)	34 (13.8)		7 (15.9)	39 (14.2)		10 (13.3)	28 (13.8)
8 risk/protective factors	60 (79.0)	197 (79.8)		37 (84.1)	219 (79.9)		64 (85.3)	162 (79.8)
Diabetes, n (%)^e	3/76 (4.0)	12/246 (4.9)	0.736	2/44 (4.6)	13/273 (4.8)	0.950	2/75 (2.7)	11/202 (5.5)	0.331
Heart disease, n (%)^e	12/75 (16.0)	59/245 (24.1)	0.141	7/44 (15.9)	68/272 (25.0)	0.189	12/74 (16.2)	51/202 (25.3)	0.113
Hypertension, n (%)^e	13/75 (17.3)	54/244 (22.1)	0.372	9/44 (20.5)	64/272 (23.5)	0.653	14/75 (18.7)	46/201 (22.9)	0.450
Depression, n (%)^e	8/74 (10.8)	31/235 (13.2)	0.591	5/44 (11.4)	31/261 (11.9)	0.922	7/74 (9.5)	24/194 (12.4)	0.505
Smoking, n (%)^e	5/73 (6.9)	14/246 (5.7)	0.713	2/44 (4.6)	17/271 (6.3)	0.655	4/74 (5.4)	12/202 (5.9)	0.866
Low-to-moderate alcohol use, n (%)^e	22/68 (32.4)	70/225 (31.1)	0.847	17/39 (43.6)	78/250 (31.2)	0.126	23/68 (33.8)	60/185 (32.4)	0.835
High cognitive activity, n (%)^e	35/74 (47.3)	95/236 (40.3)	0.284	23/42 (54.8)	111/264 (42.1)	0.123	40/74 (54.1)	82/194 (42.3)	0.083
Physical inactivity, n (%)^e	21/74 (28.4)	79/233 (33.9)	0.377	9/44 (20.5)	85/258 (33.0)	0.098	17/74 (23.0)	61/190 (32.1)	0.144
LIBRA score, mean (SD)^f^,^g	−0.93 (2.2)	−0.51 (2.2)	0.154	−1.31 (2.4)	−0.60 (2.2)	0.050	−1.29 (2.2)	−0.60 (2.2)	0.022

Note: Figures may not sum to 100% because of rounding.

Abbreviations: ADL – activities of daily living; IADL – instrumental activities of daily living; LIBRA – LIfestyle for BRAin health; MMSE – Mini-Mental State Examination; SD – standard deviation.

^aMissing data: social class n = 5; disabilities in ADLs or IADLs n = 1; MMSE score at Survey 4 n = 10; diabetes n = 1; heart disease n = 3; hypertension n = 4; depression n = 14; smoking n = 4; low-to-moderate alcohol use n = 30; high cognitive activity n = 13; physical inactivity n = 16

^bMissing data: social class n = 4; disabilities in ADLs or IADLs n = 1; MMSE score at Survey 4 n = 12; diabetes n = 1; heart disease n = 2; hypertension n = 2; depression n = 13; smoking n = 3; low-to-moderate alcohol use n = 29; high cognitive activity n = 12; physical inactivity n = 16

^cMissing data: social class n = 5; disabilities in ADLs or IADLs n = 1; MMSE score at Survey 4 n = 8; diabetes n = 1; heart disease n = 2; hypertension n = 2; depression n = 10; smoking n = 2; low-to-moderate alcohol use n = 25; high cognitive activity n = 10; physical inactivity n = 14.

^dMMSE score range: 0–30.

^eBefore data imputation.

^fAfter data imputation.

^gModified (7-item) LIBRA score range: −4.2 to +7.0.

Values in bold are statistically significant (p < 0.05).

Table 2. Prediction of outcome by risk factors and LIBRA score.

	Incident dementia (n = 323; 76 cases)			Incident severe cognitive impairment (n = 318; 44 cases)			Incident dementia/severe cognitive impairment (n = 278; 75 cases)
Model 1^a
Variable	OR	95% CI	p-Value	OR	95% CI	p-Value	OR	95% CI	p-Value
Diabetes	0.76	0.21–2.75	0.674	0.93	0.20–4.29	0.930	0.46	0.10–2.11	0.315
Heart disease	0.61	0.31–1.21	0.154	0.57	0.24–1.34	0.196	0.58	0.29–1.16	0.120
Hypertension	0.74	0.38–1.45	0.380	0.84	0.38–1.84	0.664	0.77	0.40–1.51	0.448
Depression	0.78	0.34–1.78	0.549	0.96	0.35–2.61	0.931	0.77	0.31–1.88	0.566
Smoking	1.28	0.45–3.64	0.639	0.70	0.16–3.14	0.639	0.92	0.29–2.95	0.886
Low-to-moderate alcohol use	1.04	0.57–1.88	0.908	1.64	0.84–3.21	0.146	1.04	0.57–1.91	0.888
High cognitive activity	1.36	0.81–2.29	0.248	1.68	0.87–3.24	0.121	1.59	0.93–2.73	0.091
Physical inactivity	0.79	0.44–1.40	0.413	0.53	0.24–1.15	0.110	0.63	0.34–1.17	0.145
LIBRA score^c	0.92	0.82–1.03	0.153	0.85	0.73–0.99	0.036	0.87	0.77–0.99	0.031
Model 2^b
	OR	95% CI	p-Value	OR	95% CI	p-Value	OR	95% CI	p-Value
Diabetes	0.71	0.19–2.62	0.607	0.94	0.20–4.48	0.939	0.44	0.09–2.08	0.301
Heart disease	0.67	0.33–1.34	0.257	0.61	0.26–1.46	0.269	0.64	0.32–1.31	0.223
Hypertension	0.69	0.35–1.37	0.285	0.76	0.34–1.70	0.504	0.72	0.36–1.43	0.354
Depression	0.75	0.33–1.74	0.508	0.95	0.34–2.65	0.927	0.73	0.30–1.81	0.497
Smoking	1.51	0.52–4.42	0.453	1.04	0.22–4.90	0.962	1.22	0.36–4.09	0.749
Low-to-moderate alcohol use	1.13	0.61–2.08	0.692	1.98	0.99–3.97	0.054	1.19	0.63–2.25	0.588
High cognitive activity	1.26	0.74–2.14	0.395	1.65	0.84–3.21	0.145	1.48	0.85–2.57	0.163
Physical inactivity	0.78	0.44–1.41	0.417	0.50	0.23–1.10	0.084	0.62	0.33–1.15	0.130
LIBRA score^c	0.93	0.83–1.05	0.228	0.85	0.73–0.99	0.040	0.88	0.78–1.00	0.053

Note: Abbreviations: OR – odds ratio; CI – confidence interval; LIBRA – LIfestyle for BRAin health.

^aModel 1: crude model.

^bModel 2: adjusted for age, sex and educational level.

^cThe modified version of the LIBRA score consists of the following factors: diabetes, heart disease, depression, smoking, low-to-moderate alcohol use, high cognitive activity and physical inactivity.

Values in bold are statistically significant (p < 0.05).