Associations of neighbourhood attributes with depression in mid-age and older adults: the moderating role of traffic-related air pollution and neighbourhood socioeconomic status

Figures & data

Table 1. Sample characteristics.

Characteristics	Statistic	Characteristics	Statistic
Socio-demographic characteristics		Environmental characteristics (1 km radius street-network buffers), M ± SD
Age, years (M ± SD)	61.1 ± 11.4	Population density (persons/hectare)	17.4 ± 10.0
Educational attainment, %		Street intersection density (intersections/km^2)	62.2 ± 32.2
Up to secondary	32.9	Percentage of commercial land use (% area in residential buffer)	2.5 ± 6.1
Trade, technician certificate	29.2	Percentage of parkland (% of area in residential buffer)	11.6 ± 12.5
Associate diploma & equivalent	14.6	Percentage of blue space (% of area in residential buffer)	0.2 ± 2.0
Bachelor degree, post-graduate diploma	23.3	Annual average NO2 exposure (ppb)	5.5 ± 2.1
Missing data, %	0.6
Living arrangements, %
Couple without children	49.5
Couple with children	27.5	Mental health
Other	23.0	CESD score, M ± SD	4.1 ± 4.4
Missing data, %	2.5	No depressive symptoms, %	89.1
Residential self-selection – access to destinations, M ± SD	3.0 ± 1.4	Mild depressive symptoms, %	7.2
Missing data, %	9.2	Severe depressive symptoms, %	3.7
Residential self-selection – recreational facilities, M ± SD	3.1 ± 1.5	Missing data, %	2.9
Missing data, %	7.6
Sex, female, %	55.2
Area-level IRSAD, M ± SD	6.4 ± 2.7
English-speaking background, %	89.9
Household income, %
Up to $49,999	33.8
$50,000–$99,000	27.5
$100,000 and over	29.6
Does not know or refusal	9.0
Missing data, %	2.7

Notes. M, mean; SD, standard deviation; IRSAD, Index of Relative Socioeconomic Advantage and Disadvantage where higher IRSAD scores indicate higher area-level socioeconomic status; NO₂, nitrogen dioxide; environmental characteristics have no missing data. Participants’ sex is defined in biological terms.

Table 2. Total effects of environmental attributes on depressive symptoms.

Environmental Attribute	b (95% CI)	p value
Population density (persons/hectare)	.012 (−.003, .027)	.11
Street intersection density (intersections/km^2)	−.007 (−.012, −.001)	.01
Percentage of commercial land use (% area in residential buffer)	−.003 (−.026, .021)	.83
Percentage of parkland (% of area in residential buffer)	.006 (−.006, .018)	.32
Percentage of blue space (% of area in residential buffer)	−.049 (−.117, .018)	.15
Area-level IRSAD	−.036 (−.093, .021)	.21
Annual average NO2 exposure (ppb)	−.030 (−.123, .063)	.53

Notes. b, regression coefficient; CI, confidence intervals; ppb, parts per billion. Effects in bold are statistically significant at a probability level of 0.05. Regression analyses performed on imputed data (N = 4141).

Table 3. Direct effects of environmental attributes on depressive symptoms.

Environmental Attribute	b (95% CI)	p value
Population density (persons/hectare)	.029 (.008, .050)	.01
Street intersection density (intersections/km^2)	−.008 (−.013, −.002)	.01
Percentage of commercial land use (% area in residential buffer)	−.004 (−.027, .020)	.75
Percentage of parkland (% of area in residential buffer)	.005 (−.007, .017)	.39
Percentage of blue space (% of area in residential buffer)	−.050 (−.117, .018)	.15
Area-level IRSAD	−.027 (−.085, .031)	.37
Annual average NO2 exposure (ppb)	−.037 (−.130, .057)	.44

Notes. b, regression coefficient; CI, confidence intervals; ppb, parts per billion. Effects in bold are statistically significant at a probability level of 0.05. Regression analyses performed on imputed data (N = 4141).

Figure 1. Associations between commercial land use and depressive symptoms at different values of neighbourhood socioeconomic status (y-axis) and annual average concentrations of NO₂. Legend: IRSAD, Index of Relative Advantage and Disadvantage; panel A, NO₂ at mean − 1SD value; panel B, NO₂ at mean value; panel C, NO₂ at + 1SD value; Slope of commercial land use, slope of the relationship between commercial land use and depressive symptoms.

Data availability statement

Data that support the findings of this study are available on request.