Pilot study to examine the effects of indoor daylight exposure on depression and other neuropsychiatric symptoms in people living with dementia in long-term care communities

Figures & data

Table 1 Comparisons by community

	1	2	3	4	5	6	7	8	p-value
N	18	11	18	9	7	6	5	3
Treatment	Daylight	Control	Daylight	Control	Daylight	Control	Control	Daylight
mLuxAVG	230*	20	100	56	75	57	49	120
Baseline
NPI-NH	18.4 (0, 96)	22.7 (2, 54)	11.5 (0, 66)	11.6 (0, 46)	20.6 (3, 43)	9.7 (1, 29)	18.6 (9, 32)	18.3 (0, 31)	0.64
CSDD	9.4 (0, 20)	8.7 (2, 16)	4.1 (0, 17)	0.9 (0, 2)	1.6 (0, 4)	1.3 (0, 3)	4.8 (0, 8)	1.7 (0, 4)	0.0003
End
NPI-NH	20.3 (0, 93)	26.8 (5, 62)	10.7 (0, 39)	13.6 (0, 44)	6.4 (0, 18)	6.3 (0, 22)	29.2 (2, 59)	14.7 (0, 30)	0.08
CSDD	4.8 (0, 17)	10.9 (2, 24)	1.9 (0, 7)	1.0 (0, 2)	1.8 (0, 4)	1.8 (0, 5)	6.4 (0, 11)	1.3 (0, 4)	0.0001
Change
NPI-NH	1.9 (−47, 42)	4.1 (−9, 36)	−0.8 (−27, 20)	2.0 (−5, 16)	−14.1 (−25, −3)	−3.3 (−28, 13)	10.6 (−7, 41)	−3.7 (−17, 6)	0.13
CSDD	−4.6 (−15, 9)	2.2 (−8, 15)	−2.6 (−10, 3)	0.1 (−2, 2)	0.2 (0, 1)	0.2 (0, 1)	1.6 (0, 3)	−0.3 (−1, 0)	0.1

Notes: Numbers in table are mean (minimum, maximum); p-value from analysis of variance; participants with baseline CSDD >4 months before enrollment excluded;

* median value.

Abbreviations: mLux_AVG, average melanopic illuminance at 3 m from windows; NPI-NH, Neuropsychiatric Inventory Nursing Home Version; CSDD, Cornell Scale for Depression in Dementia.

Table 2 Baseline and endpoint comparisons by treatment

	Daylight	Control	p-value between treatments
N	46	31
Female	31 (67.4%)	25 (80.6%)	0.30
Age (years)	85.6 (1.0)	84.7 (1.3)	0.56
White race	42 (91.3%)	29 (93.5%)	1.00
Clinical group			0.69
AD	17 (37.0%)	8 (25.8%)
Frontotemporal dementia	1 (2.2%)	1 (3.2%)
Lewy body dementia	0	1 (3.2%)
Vascular dementia	2 (4.3%)	1 (3.2%)
Dementia NOS	19 (41.3%)	17 (54.8%)
Mild cognitive impairment	6 (13.0%)	2 (6.5%)
Not specified	1 (2.2%)	1 (3.2%)
Years in community	1.2 (0.2)	0.6 (0.3)	0.14
Baseline outcomes
NPI-NH	16.2 (3.2)	16.1 (2.7)	0.97
CSDD	4.2 (1.9)	3.9 (1.9)	0.93
Endpoint outcomes
NPI-NH	13.4 (4.2)	19.1 (4.4)	0.35
CSDD	2.7 (2.1)	5.3 (2.0)	0.39
Change (endpoint minus baseline) outcomes
NPI-NH	−2.8 (2.9)	3.1 (3.2)	0.17
p-value within group	0.33	0.33
CSDD	−2.0 (0.9)	1.5 (1.0)	0.01
p-value within group	0.025	0.13
mLuxAVG	159.3 (13.8)	42.3 (3.1)	<0.0001

Notes: Numbers in table are mean (SEM); for age, years in community, and trial outcome measures, p-values between treatments are by mixed effects linear models, specifying a random effect for community to account for within-community clustering. Sample size for years in community (n=46 daylight, n=24 control); sample size for CSDD: (n=36 daylight, n=28 control), intraclass correlation (ICC) for within-community change in outcomes: ICC =0.065 for change in NPI-NH; ICC =0.03 for change in CSDD.

Abbreviations: AD, Alzheimer’s disease; mLux_AVG, average melanopic illuminance at 3 m from windows; NOS, not otherwise specified; NPI-NH, Neuropsychiatric Inventory Nursing Home Version; CSDD, Cornell Scale for Depression in Dementia; SEM, standard error of the mean.

Table 3 Correlations among mLux_AVG and change in outcomes

	Spearman Correlation (p-value)	Beta coefficient (SE) [p-value] from mixed model
NPI-NH	0.002 (0.99)	0.012 (0.026) [0.64]
CSDD	−0.37 (0.002)	−0.016 (0.01) [0.054]

Notes: Sample size: n=77 in NPI-NH analysis; n=64 in CSDD analysis.

Abbreviations: NPI-NH, Neuropsychiatric Inventory Nursing Home Version; CSDD, Cornell Scale for Depression in Dementia; mLuxAVG, average melanopic illuminance at 3 m from windows; SE, standard error.

Figure 1 CSDD change by community.

Note: Intraclass correlation of Cornell change (within-community correlation) =0.03.

Abbreviation: CSDD, Cornell Scale for Depression in Dementia.

Figure 2 NPI-NH change by community.

Note: Intraclass correlation of NPI-NH change (within-community correlation) =0.065.

Abbreviation: NPI-NH, Neuropsychiatric Inventory Nursing Home Version.

Figure 3 Scatter plot of changes in CSDD.

Abbreviations: CSDD, Cornell Scale for Depression in Dementia; mLux_AVG, average melanopic illuminance at 3 m from windows.

Table 4 Treatment group comparisons on behavioral and depression change: baseline Cornell >10

	Daylight	Control	p-value between treatment
NPI-NH
Baseline	14.3 (12.0)	34.7 (15.5)	0.34
End of study	25.4 (9.3)	39.0 (10.4)	0.37
Change	10.6 (15.7)	4.3 (19.7)	0.81
CSDD
Baseline	16.8 (1.3)	12.7 (1.5)	0.09
End of study	5.6 (2.6)	13.5 (2.9)	0.09
Change	−11.2 (2.7)	0.7 (3.1)	0.03

Notes: p-values from linear mixed effects models, with random effect for community. Numbers in table are model-estimated mean (SE) change in trial outcomes. N=9 in analysis (n=5 daylight, n=4 control).

Abbreviations: NPI-NH, Neuropsychiatric Inventory Nursing Home Version; CSDD, Cornell Scale for Depression in Dementia; SE, standard error.