Environmental exposures and their genetic or environmental contribution to depression and fatigue: a twin study in Sri Lanka

Table 3 Aetiology of the association between depression and measured environments

Measured environment	Sex group	Time period	Depression (lifetime-ever)
			MZ differences OR (95% CI) 'E'	Interaction: familiality¹ X zygosity, z score (p) 'A'	Familiality¹ OR (95% CI)
Early school leaving	Men	Prior to age 16 in 95% of cases	4.12 (1.81 - 9.41)	0.82 (0.413)	0.66 (0.40-1.10)
	Women		1.68 (0.77-3.63)	0.70 (0.484)	1.34 (0.94-1.90)
Standard of Living	Men	Current	2.37 (1.06 - 5.31)	0.93 (0.350)	1.00 (0.59-1.72)
	Women		0.67 (0.34-1.30)	1.09 (0.277)	1.19 (0.82-1.74)
Life Events	Men	Past year	1.98 (1.29-3.03)	0.15 (0.877)	1.50 (1.11-2.03)
	Women		1.27 (0.89-1.83)	1.99 (0.046)²	1.61 (1.27-2.04)
Parental care (continuous)	Men	Prior to age 17 (retrospective)	1.04 (0.88-1.23)	3.11 (0.002)³	0.93 (0.84-1.03)
	Women		1.00 (0.90-1.11)	0.10 (0.920)	0.88 (0.82-0.93)

Logistic regressions examining MZ differences ('E') (predicting within-pair difference in depression from within-pair differences in environments), and familiality ('A' and 'C') (predicting depression from co-twin's environmental experiences, in both MZ and DZ pairs)
¹Familiality: all twins except DZOS
²The cross-twin relationship between life events and depression in women by zygosity was OR 1.97 (1.48-2.63) in MZ pairs, and 1.17 (0.76-1.82) in DZ pairs.
³The cross-twin relationship between care and depression in men by zygosity was OR 0.81 (0.73-0.90) in MZ pairs and 1.10 (0.93-1.31) in DZ pairs.

ISSN: 1471-244X