. 2020 Jun 3;59(11):1218–1239.e3. doi: 10.1016/j.jaac.2020.05.009

Table 3.

Longitudinal Studies Examining Social Isolation/Loneliness and Subsequent Mental Health Outcomes

Author (year), country	Sample (selection criteria)	Total N (% male participants)	Child (≤11 y)/adolescent (12−18 y)/young adult (≥19 y)	Age range, y	Mean age (SD) at T1	Social isolation/ loneliness measure	Mental health measures	Cross-Sectional associations r (p)	Length of follow-up, y	Is social isolation/loneliness associated with later mental health?
Author (year), country	Sample (selection criteria)	Total N (% male participants)	Child (≤11 y)/adolescent (12−18 y)/young adult (≥19 y)	Age range, y	Mean age (SD) at T1	Social isolation/ loneliness measure	Mental health measures	Cross-Sectional associations r (p)	Length of follow-up, y	Depression	Anxiety
Boivin et al. (1995),⁶¹ Canada	School students	774 (51.8)	Child	9–12	10.8 (NS)	LSDQ	CDI	Lon-Dep 0.53 (p < .001)	1	T1 Lon – T2 Dep: r = 0.36 (p < .01) T1 Lon accounted for 8.3% of variance in T2 Dep
Christ et al. (2017),⁶² USA	National Survey of Child and Adolescent Well-being (child welfare cohort)	2776 (47)	Adolescent	11–17	13.5 (NS)	LDSQ 7 peer isolation items	4 items from YSR	NS	7	Controlling for caregiver neglect and covariates, a 1-SD increase in peer isolation was associated with a 0.49-SD increase in depression
Danneel et al. (2019),⁶³ Belgium	Longitudinal cohorts	Sample 1: 1116 (51.1), Sample 2: 1423 (47.6), Sample 3: 549 (37.33)	Adolescent	Sample 1: 11–17 Sample 2: 11–18 Sample 3: 12–17	Sample 1: 13.79 (0.94) Sample 2: 13.59 (0.98) Sample 3: 14.82 (0.79)	LACA peer-related loneliness subscale	Samples 1 and 3 – SAS-A; CES-D. Sample 2 - CDI	Lon-Social anxiety 0.58 ≤ r ≤ 0.67 Lon-Dep 0.48 ≤ r ≤ 0.56 (all <.01)	1	Not significant	Lon → Social anxiety β = 0.10 (p < .001)
Fontaine et al. (2009),⁶⁴ USA	School students (longitudinal cohort)	NS (52)	Child	NS Estimated 5–9	NS	LSDQ (T2)	Internalizing items from: CBCL (mother T1 and T3); TRF (teacher T1 and T2); YSR (self T2 and T3)	NS	2-3	T2 Lon → Anx/Dep symptoms at T3 γ² = 0.18, z = 2.60 (p < .01)
Jones et al. (2011),⁶⁵ USA	Longitudinal cohort	889 (50)	Child	6	NS	LSDQ	CDI short form	NS	9	Indirect effects T1 Lon → T2 Suicidal thoughts through Dep (β = 0.06, p < .001)
Ladd and Ettekal (2013),⁶⁶ USA	School students (longitudinal cohort)	478 (50)	Adolescent	12–18	12.0 (n.s)	LSDQ – revised - 3 items	Depression items CBCL (parent); TRF (teacher); YSR (self)	Lon-Dep 0.19 (p < .01) (parent), 0.38 (p < .001) (teacher) 0.62 (p < .001) (self)	7	Changes in Lon associated with changes in Dep reported by teachers (r = 0.63, p < .001) and adolescents (r = 0.65, p < .001), but not parents (r = 0.18,p = .13)
Lalayants and Prince (2015),⁶⁷ multiple countries	National Survey of Child and Adolescent Wellbeing (child welfare cohort)	356 (0)	Adolescent	11–12	NS	LSDQ	CDI	NS	1.5	T1 Lon → T2 Dep AOR = 2.93, CI = 1.74−4.91 (p < .001) T1 lonely female participants were 5.09 times more likely (CI 2.24−11.56 (p < .001) to be depressed at T2
Lapierre et al. (2019),⁶⁸ USA	College Students	346 (33.6)	Young adult	17–20	19.11 (0.75)	UCLA Loneliness Scale	10-Item CES-D	Lon-Dep 0.628 (T1), 0.666 (T2) (p < .001)	0.25	T1 Lon – T2 Dep (r = 0.524, p < .001) T1 Lon → T2 Dep b = 0.21, SE = .05 (p < .001)
Lasgaard et al. (2011b),⁶⁹ Denmark	School students	T1: 1009 (43) T2: 541 (40)	Adolescent/Young adult	15–26	17.11 (1.11)	SELSA-short form; MSPSS	BAI-Y, BDI-Y	Lon-Dep 0.61 (p < .0005) Lon-Anx 0.51 (p < .0005). Soc support– Dep r = −0.12, −0.18, −0.28 (all p < .0005)	1	T1 Lon→ T2 Dep (r = 0.37, p < .0005) Cross-lagged structural equation modeling found T1 Lon did not predict Dep at T2
Liu et al. (2020),⁷⁰ China	College students	741 (28.3)	Young adult	NS (estimated 18−20)	18.47 (0.87)	6 item index of social isolation based on only child status, number of friends, frequency of contact with friends and family; UCLA Loneliness Scale	SDS	NS	3	Female participants: T1 isolation associated with increased Dep (β = 0.22, p < .001) Lon associated with increased Dep (β = 0.23, p < .001) Male participants: T1 isolation associated with increased Dep (β = 0.25, p < .01) Lon did not predict Dep (β = 0.14, p > .05)
Mak et al. (2018),⁷¹ USA	School students (randomized trial)	687 (47.7)	Adolescent	NS (estimated 11–14)	11.27 (0.49)	LSDQ	SAS-A	Lon-social anxiety 0.41−0.45 (p < .01)	1.5 (T2), 3 (T3)		T1 Lon → T2 Social Anxiety (β = 0.09, p < .05). T2 Lon → T3 Social Anxiety (β = 0.12, p < .01) By gender: T2 Lon → T3 Social Anx: Boys (β = 0.22, p < .001) Girls (β = 0.01 p = .79)
Matthews et al. (2015),⁷² UK	Twin birth cohort	2232 (NS)	Child	5	NS	6 items from CBCL (parent) and TRF (teacher)	MASC	NS	7		T1 social isolation failed to predict T2 Anx, controlling for T1 Anx
Qualter et al. (2010),⁷³ UK	School students	296 (49.3)	Child	5	NS	T1 and T2: Peer and Parent subscales LACA	T1: T-CARS T2 and T3: DDPCA	T1 Peer Lon-internalizing symptoms 0.32 (p < .01) Parent Lon-Internalizing Symptoms 0.09. T2 Peer Lon- Dep 0.13 (p < .05) Parent Lon-Dep 0.12 (p < .05)	8	T1 Peer Lon-T2 Dep r = 0.07 T1 Peer Lon-T3 Dep r = 0.06 T2 Peer Lon – T3 Dep r = 0.12 (p < .05) T1 Parent Lon – T2 Dep r = 0.19, p < .01 T1 Parent Lon-T3 Dep r = 0.13 (p < .05) T2 Parent Lon-T3 Dep r = 0.08 Structural model: Duration of Peer Lon → T3 Dep T1 and T2 Peer Lon, Parent Lon (T1, T2, and duration) did not independently predict T3 Dep
Schinka et al. (2013),⁷⁴ USA	Longitudinal cohort study	832 (53)	Child	9	NS	LDSQ	T1: CBCL (mother) T3: CDI−Short form; Suicide items from CBCL and YSR	T3 Lon-Dep -0.10 (p < .01) Lon− suicidal ideation r = 0.02 Lon− suicide attempt r = 0.4	2 (T2), 6 (T3)	T1 Lon-T3 Dep r = 0.01 T2 Lon-T3 Dep r = −0.01 T1 Lon-T3 Suicidal ideation r = 0.00 T2 Lon-T3 suicidal ideation r = 0.03 T1 Lon-T3 suicide attempt r = 0.02 T2 Lon-T3 suicide attempt r = −0.01
Vanhalst, Goosens et al. (2013)⁷⁵ and Vanhalst, Klimstra et al. (2012),⁷⁶ Netherlands	Community sample via municipality registers	389 (53)	Adolescents	15	15.22 (0.60)	LACA Peer-related loneliness subscale	6 item depression questionnaire; SCARED generalized anxiety, panic and social anxiety subscales.	Lon-Dep 0.34−0.50 (p < .001) Lon- Perceived stress 0.23 (p < .001). Lon- Generalized Anx 0.40 (p < .001), Lon-Panic 0.13 (p < .05), Lon− Social phobia 0.47 (p < .001)	5	T1 Lon → T2 Dep symptoms (B = 0.13, p < .001)
Vanhalst, Luyckx et al. (2012)⁷⁷ Belgium	University students	Sample 1: 514 (10.9) Sample 2: 437 (17)	Young adults	Sample: 19.62 (0.62) Sample 2: 18.22 (1.21)	NS	Sample 1: 8-item revised UCLA Loneliness Scale. Sample 2: LACA Peer-related loneliness subscale	Sample 1: 12-item CES-D Sample 2: 20-item CES-D	Sample 1: Lon-Dep 0.49−0.52 (p < .001) Sample 2: Lon-Dep r = 0.40−0.60 (p < .001)	2	Sample 1: T1 lon – T2 Dep r = 0.35 (p < .001) T1 lon – T3 Dep r = 0.36 (p < .001) Lon → associated with Dep across both time intervals. Sample 2: cross-lagged path from Lon associated with Dep (b = 0.12, p < .05)
Wang et al. (2020),⁷⁸ China	School students	921 (48.3)	Adolescents	12–15	12.98 (0.66)	Revised UCLA Loneliness Scale (T1 and T2)	SCARED; DSRSC (T1 and T3)	T1 Lon- Anx 0.40 (p < .001) Lon-Dep 0.57 (p < .001)	1	T1 Lon-T3 Dep 0.36 (p < .001) T2 Lon-T3 Dep 0.46 (p < .001)	T1 Lon-T3 Anx 0.29, p<.001. T2 Lon-T3 Anx 0.36 (p < .001)
Zhou et al. (2020),⁷⁹ China	School students	866 (49)	Adolescents	11–15	12.98 (0.67)	UCLA Loneliness Scale (T1 and T2)	DSRSC (T3)	T1 Lon-Dep r = 0.56 (p < .001)	2	T1 Lon-T3 Dep r = 0.38 (p < .001) Controlling for age, sex, and SES, T2 Lon-T3 Dep adjusted b = 0.34 (p < .001)

Note: Anx = Anxiety; BAI-Y = Beck Anxiety Inventory for Youth; BDI-Y = Beck Depression Inventory for Youth; CBCL = Child Behaviour Checklist; CDI = Children’s Depression Inventory; CES-D = Center for Epidemiologic Studies Depression Scale; DDPCA = Depression Profile for Children and Adolescents; Dep = depression; DSRSC = Birleson Depression Self-Rating Scale for Children; Lon = Loneliness; LSDQ = Loneliness and Social Dissatisfaction Questionnaire; LACA = Loneliness and Aloneness Scale for Children and Adolescents; MASC = Multidimensional Anxiety Scale for Children; MSPSS = Multidimensional Scale of Perceived Social Support; NS = not specified; SAS-A = Social Anxiety Scale for Adolescents; SCARED = Scale for Child Anxiety Related Emotional Disorders; SES = socioeconomic status; SDS = Zung Self-rating Depression Scale; SELSA = Social and Emotional Loneliness Scale for Adults; T-CARS = Teacher-Classroom Adjustment Rating Scale; T1 = Time 1; T2 = Time 2; T3 = Time 3; TRF = Teacher Rating Form; YSR = Youth Self-Report Form.