. 2019 Nov 19;55(7):839–876. doi: 10.1007/s00127-019-01800-z

Table 1.

Trials that included subjective social isolation as outcome

Main author, sample and setting	Intervention categorisation	Intervention name and duration	Follow-up	Social isolation and other outcome measures	Subjective social isolation outcomes
Group-based intervention
Hasson-Ohayon [42]—210 adults with severe mental illness Psychiatric community rehabilitation centre in Israel (secondary care setting)	Psychoeducation, social skills training	Illness Management and Recovery Programme vs. treatment-as-usual control group Duration: 8 months	End-of-treatment follow-up (8 months)	Subjective social isolation outcome: the Multidimensional Scale of Perceived Social Support (MSPSS) [57] Other outcome: personal recovery	No significant changes in perceived social support for either group. p > 0.05^a
Silverman [43]—96 adults with varied Axis I diagnoses Acute care psychiatric unit in a University hospital, the Midwestern region in the US (secondary care setting)	Psychoeducation	Live educational music therapy (condition A), recorded educational music therapy (condition B), education without music (condition C), recreational music therapy without education (condition D) Duration: 24 weeks	End-of-treatment follow-up (24 weeks)	Subjective social isolation outcome: the MSPSS [57]	No significant between-group difference in total perceived social support for condition A vs. B, condition A and B vs. condition C, as well as for condition A and B vs. D (all p > 0.05) (F (3.87) = 1.50, p = 0.22) Partial effect size = 0.028 for support from significant other, 0.015 for support from family, 0.094 for support from friends, and 0.049 for total support Only a significant between-group difference between condition A vs. D on a friend subscale, 95% CI (0.47, 10.40), adjusted p = 0.02, mean difference = 5.34
Boevink [44] - 163 adults with mental illness Mental health care organisations (community treatment team and sheltered housing organisations) in the Netherlands (secondary care setting)	Supported socialisation	Toward Recovery, Empowerment and Experiential Expertise (TREE) + care-as-usual vs. care-as-usual control group Duration: 104 weeks for early starters and 52 weeks for late starters	1 medium-term follow-up: 12 months (post-baseline) 1 long-term follow-up: 24 months (post-baseline)	Subjective social isolation outcome: the De Jong-Gierveld Loneliness Scale [58] Other outcomes: quality of Life; psychiatric symptoms	No between-group difference in loneliness, 95% CI (− 0.31, 0.30) (effect size linear tread B = − 0.053, p = 0.98), standardised effect size was − 0.001 for each year of exposure to TREE programme
Eggert [45]—105 high school students with poor grades (moderate or severe depression) 5 urban high schools in the US (general population setting)	Supported socialisation, social skills training and wider community approaches	Assessment protocol plus 1-semester Personal Growth Class (PGCI) vs. Assessment protocol plus a 2-semester Personal Growth Class (PGCII) vs. an assessment protocol-only Duration: 5 months or 90 class days in length for PGCI, and 10 months or 190 class days in length for PGCII	2 medium-term follow-ups: 5 and 10 months (post-baseline)	Subjective social isolation outcomes: perceived social support was measured by calculating average ratings across 6 network support sources. Instrumental and expressive support provided by each network support source (e.g. family, friends) was also rated on a scale Other outcome: depressive symptoms	All 3 groups showed increased network social support F linear (1,100) = 32.08, p < 0.001 No significant between-group difference between all groups F linear (1,100) = 1.98, p = 0.143
Individual-based intervention
Zang [46]—30 adults aged 28–80 with post-traumatic stress disorder (PTSD) Beichuan County in China (general population setting)	Changing cognitions	Narrative Exposure Therapy (NET) vs. Narrative Exposure Therapy Revised (NET-R) vs. waiting-list control group Duration: 2 weeks for NET and 1 week for NET-R group	End-of-treatment follow-up (2 weeks for NET, 1 week for NET-R) 2 medium-term follow-ups: 1 week (for NET) or 2 weeks (for NET-R), and 3 months	Subjective social isolation outcome: the MSPSS [57] Other outcomes: anxiety and depressive symptoms; PTSD symptoms	Both NET and NET-R showed effects on perceived social support after treatment, but no significant between-group difference between the two groups (F (2,26) = 0.14, p > 0.05) No significant between-group difference between either treatment group (NET and NET-R) and the waiting-list control in perceived social support (both p > 0.05)
Zang [47]—22 adults aged 37–75 with PTSD Beichuan Country in China (general population setting)	Changing cognitions	NET intervention vs. waiting-list control group Duration: 2 weeks	End-of-treatment follow-up (2 weeks) 2 medium-term follow-ups: 2 weeks, and 2 months	Subjective social isolation outcome: the MSPSS [57] Other outcomes: subjective level of distress; depressive symptoms	No significant between-group difference in perceived social support (F (1,19) = 4.25, p = 0.05, d = 0.33)
Gawrysiak [48]—30 adults aged ≥ 18 with depression A public Southeastern University in the US (general population setting)	Psychoeducation, social skills training and supported socialisation	Behavioural Activation Treatment for Depression (BATD) vs. no-treatment control group Duration: single session lasted 90 min	1 medium-term follow-up: 2 weeks	Subjective social isolation outcome: the MSPSS [57] Other outcomes: depressive symptoms; anxiety symptoms	No significant between-group difference in perceived social support (F (1,28) = 3.11, p = 0.08, d = 0.70)
Conoley [49]—57 female psychology undergraduate students with moderate depression University Psychology department in the US (general population setting)	Changing cognitions	Reframing vs. self-control vs. waiting-list control group Duration: 2 weeks	End-of-treatment follow-up (2 weeks) 1 medium-term follow-up: 2 weeks	Subjective social isolation outcome: the Revised University of California Los Angeles (UCLA) Loneliness Scale [59]; The Causal Dimension Scale [60] Other outcome: depressive symptoms	No significant treatment effect was found (F (2,108) = 0.60, p > 0.05^b)
Bjorkman [50]—77 adults aged 19–51 with severe mental illness Case management service in Sweden (secondary care setting)	Social skills training	The case management service vs. standard care Duration: unclear	2 long-term follow-ups: 18 and 36 months	Subjective social isolation outcome: the abbreviated version of the Interview Schedule for Social Interaction (ISSI) [61] Other outcomes: psychiatric symptoms; quality of life; use of psychiatric services	No significant between-group difference between two groups in social outcomes (p > 0.05)^c
Mixed-format (group- and individual-based)
Mendelson [51]—78 depressed women aged 14–41 who were either pregnant or had a child less than 6 months old Home visiting programme in Baltimore City in the US (general population setting)	Changing cognitions	Standard home visiting services + The Mother and Babies (MB) course vs. standard home visiting services + information on perinatal depression Duration: 6 weeks	End-of-treatment follow-up (6 weeks) 2 medium-term follow-ups: 3 and 6 months	Subjective social isolation outcome: the Interpersonal Support Evaluation List (ISEL) [62]	No significant between-group difference in perceived social support, β = 6.67, SE = 0.03, p < 0.10^d
Masia-Warner [52]—35 high school students with social anxiety disorder 2 parochial high schools in New York, US (general population setting)	Psychoeducation/social skills training, supported socialisation and changing cognitions	Skills for Social and Academic Success vs. waiting-list control group Duration: 3 months	End-of-treatment follow-up (3 months) 1 medium-term follow-up: 9 months	Subjective social isolation outcome: Loneliness Scale [63] Other outcomes: anxiety symptoms; social phobic symptoms; depressive symptoms	No significant treatment effect, effect size = 0.20^e, p > 0.05
Online intervention
Kaplan [53]—300 adults with schizophrenia spectrum or affective disorder Online in the US (general population setting)	Supported socialisation	Experimental peer support listserv vs. experimental peer support bulletin board vs. waiting-list control group Duration: 12 months	2 medium-term follow-ups: 4 and 12 months (post-baseline)	Subjective social isolation outcome: the Medical Outcomes Study (MOS) Social Support Survey [64] Other outcomes: personal recovery; quality of life; psychiatric symptoms	No significant between-group difference on MOS (F (1,298) = 0.08, p = 0.93), also not significant when two experimental groups compared to the control group separately (p > 0.05)
Rotondi [54]—30 patients aged ≥ 14 with schizophrenia or schizoaffective disorder In- and out-patient psychiatric care units and psychiatric rehabilitation centres in Pittsburgh, Pennsylvania (secondary care setting)	Psychoeducation	Telehealth intervention vs. usual care group Duration: unclear	2 medium-term follow-ups: 3 and 6 months (post-baseline)	Subjective social isolation outcome: the informational support and emotional support subscales of the instrument that was developed by Krause and Markides [65]	No significant between-group difference on perceived social support (F (1,27) = 3.79, p = 0.062)
O’Mahen [55]—83 women aged > 18 with major depressive disorder (MDD) Online in the UK (general population setting)	Psychoeducation and supported socialisation	Netmums Helping with Depression (HWD) vs. treatment-as-usual control group Duration: unclear	End-of-treatment follow-up (unclear) 1 medium-term follow-up: 6 months	Subjective social isolation outcome: the Social Provision Scale [66] Other outcomes: depressive symptoms; anxiety symptoms	No significant between-group difference in perceived support between the intervention and control group (95% CI 1.02, − 0.02), medium effect size = 0.50 (p = 0.27)
Interian [56]—103 veterans with PTSD Online in the US (primary care setting)	Psychoeducation and changing cognitions	The Family of Heroes intervention vs. no-treatment control group Duration: unclear	1 medium-term follow-up: 2 months (post-baseline)	Subjective social isolation outcome: the family subscale of the MSPSS [57]	Intervention group reported a higher chance of having a decreased perceived family support over time than the control group (p = 0.04)^f

Main author, sample and setting

Intervention categorisation

Intervention name and duration

Follow-up

Social isolation and other outcome measures

Subjective social isolation outcomes

Group-based intervention

Hasson-Ohayon [42]—210 adults with severe mental illness

Psychiatric community rehabilitation centre in Israel (secondary care setting)

Psychoeducation, social skills training

Illness Management and Recovery Programme vs. treatment-as-usual control group

Duration: 8 months

End-of-treatment follow-up (8 months)

Subjective social isolation outcome: the Multidimensional Scale of Perceived Social Support (MSPSS) [57]

Other outcome: personal recovery

No significant changes in perceived social support for either group. p > 0.05^a

Silverman [43]—96 adults with varied Axis I diagnoses

Acute care psychiatric unit in a University hospital, the Midwestern region in the US (secondary care setting)

Psychoeducation

Live educational music therapy (condition A), recorded educational music therapy (condition B), education without music (condition C), recreational music therapy without education (condition D)

Duration: 24 weeks

End-of-treatment follow-up (24 weeks)

Subjective social isolation outcome: the MSPSS [57]

No significant between-group difference in total perceived social support for condition A vs. B, condition A and B vs. condition C, as well as for condition A and B vs. D (all p > 0.05)

(F (3.87) = 1.50, p = 0.22)

Partial effect size = 0.028 for support from significant other, 0.015 for support from family, 0.094 for support from friends, and 0.049 for total support

Only a significant between-group difference between condition A vs. D on a friend subscale, 95% CI (0.47, 10.40), adjusted p = 0.02, mean difference = 5.34

Boevink [44] - 163 adults with mental illness

Mental health care organisations (community treatment team and sheltered housing organisations) in the Netherlands (secondary care setting)

Supported socialisation

Toward Recovery, Empowerment and Experiential Expertise (TREE) + care-as-usual vs. care-as-usual control group

Duration: 104 weeks for early starters and 52 weeks for late starters

1 medium-term follow-up: 12 months (post-baseline)

1 long-term follow-up: 24 months (post-baseline)

Subjective social isolation outcome: the De Jong-Gierveld Loneliness Scale [58]

Other outcomes: quality of Life; psychiatric symptoms

No between-group difference in loneliness, 95% CI (− 0.31, 0.30) (effect size linear tread B = − 0.053, p = 0.98), standardised effect size was − 0.001 for each year of exposure to TREE programme

Eggert [45]—105 high school students with poor grades (moderate or severe depression)

5 urban high schools in the US (general population setting)

Supported socialisation, social skills training and wider community approaches

Assessment protocol plus 1-semester Personal Growth Class (PGCI) vs. Assessment protocol plus a 2-semester Personal Growth Class (PGCII) vs. an assessment protocol-only

Duration: 5 months or 90 class days in length for PGCI, and 10 months or 190 class days in length for PGCII

2 medium-term follow-ups: 5 and 10 months (post-baseline)

Subjective social isolation outcomes: perceived social support was measured by calculating average ratings across 6 network support sources. Instrumental and expressive support provided by each network support source (e.g. family, friends) was also rated on a scale

Other outcome: depressive symptoms

All 3 groups showed increased network social support F linear (1,100) = 32.08, p < 0.001

No significant between-group difference between all groups F linear (1,100) = 1.98, p = 0.143

Individual-based intervention

Zang [46]—30 adults aged 28–80 with post-traumatic stress disorder (PTSD)

Beichuan County in China (general population setting)

Changing cognitions

Narrative Exposure Therapy (NET) vs. Narrative Exposure Therapy Revised (NET-R) vs. waiting-list control group

Duration: 2 weeks for NET and 1 week for NET-R group

End-of-treatment follow-up (2 weeks for NET, 1 week for NET-R)

2 medium-term follow-ups: 1 week (for NET) or 2 weeks (for NET-R), and 3 months

Subjective social isolation outcome: the MSPSS [57]

Other outcomes: anxiety and depressive symptoms; PTSD symptoms

Both NET and NET-R showed effects on perceived social support after treatment, but no significant between-group difference between the two groups (F (2,26) = 0.14, p > 0.05)

No significant between-group difference between either treatment group (NET and NET-R) and the waiting-list control in perceived social support (both p > 0.05)

Zang [47]—22 adults aged 37–75 with PTSD

Beichuan Country in China (general population setting)

Changing cognitions

NET intervention vs. waiting-list control group

Duration: 2 weeks

End-of-treatment follow-up (2 weeks)

2 medium-term follow-ups: 2 weeks, and 2 months

Subjective social isolation outcome: the MSPSS [57]

Other outcomes: subjective level of distress; depressive symptoms

No significant between-group difference in perceived social support (F (1,19) = 4.25, p = 0.05, d = 0.33)

Gawrysiak [48]—30 adults aged ≥ 18 with depression

A public Southeastern University in the US (general population setting)

Psychoeducation, social skills training and supported socialisation

Behavioural Activation Treatment for Depression (BATD) vs. no-treatment control group

Duration: single session lasted 90 min

1 medium-term follow-up: 2 weeks

Subjective social isolation outcome: the MSPSS [57]

Other outcomes: depressive symptoms; anxiety symptoms

No significant between-group difference in perceived social support (F (1,28) = 3.11, p = 0.08, d = 0.70)

Conoley [49]—57 female psychology undergraduate students with moderate depression

University Psychology department in the US (general population setting)

Changing cognitions

Reframing vs. self-control vs. waiting-list control group

Duration: 2 weeks

End-of-treatment follow-up (2 weeks)

1 medium-term follow-up: 2 weeks

Subjective social isolation outcome: the Revised University of California Los Angeles (UCLA) Loneliness Scale [59]; The Causal Dimension Scale [60]

Other outcome: depressive symptoms

No significant treatment effect was found (F (2,108) = 0.60, p > 0.05^b)

Bjorkman [50]—77 adults aged 19–51 with severe mental illness

Case management service in Sweden (secondary care setting)

Social skills training

The case management service vs. standard care

Duration: unclear

2 long-term follow-ups: 18 and 36 months

Subjective social isolation outcome: the abbreviated version of the Interview Schedule for Social Interaction (ISSI) [61]

Other outcomes: psychiatric symptoms; quality of life; use of psychiatric services

No significant between-group difference between two groups in social outcomes (p > 0.05)^c

Mixed-format (group- and individual-based)

Mendelson [51]—78 depressed women aged 14–41 who were either pregnant or had a child less than 6 months old

Home visiting programme in Baltimore City in the US (general population setting)

Changing cognitions

Standard home visiting services + The Mother and Babies (MB) course vs. standard home visiting services + information on perinatal depression

Duration: 6 weeks

End-of-treatment follow-up (6 weeks)

2 medium-term follow-ups: 3 and 6 months

Subjective social isolation outcome: the Interpersonal Support Evaluation List (ISEL) [62]

No significant between-group difference in perceived social support, β = 6.67, SE = 0.03, p < 0.10^d

Masia-Warner [52]—35 high school students with social anxiety disorder

2 parochial high schools in New York, US (general population setting)

Psychoeducation/social skills training, supported socialisation and changing cognitions

Skills for Social and Academic Success vs. waiting-list control group

Duration: 3 months

End-of-treatment follow-up (3 months)

1 medium-term follow-up: 9 months

Subjective social isolation outcome: Loneliness Scale [63]

Other outcomes: anxiety symptoms; social phobic symptoms; depressive symptoms

No significant treatment effect, effect size = 0.20^e, p > 0.05

Online intervention

Kaplan [53]—300 adults with schizophrenia spectrum or affective disorder

Online in the US (general population setting)

Supported socialisation

Experimental peer support listserv vs. experimental peer support bulletin board vs. waiting-list control group

Duration: 12 months

2 medium-term follow-ups: 4 and 12 months (post-baseline)

Subjective social isolation outcome: the Medical Outcomes Study (MOS) Social Support Survey [64]

Other outcomes: personal recovery; quality of life; psychiatric symptoms

No significant between-group difference on MOS (F (1,298) = 0.08, p = 0.93), also not significant when two experimental groups compared to the control group separately (p > 0.05)

Rotondi [54]—30 patients aged ≥ 14 with schizophrenia or schizoaffective disorder

In- and out-patient psychiatric care units and psychiatric rehabilitation centres in Pittsburgh, Pennsylvania (secondary care setting)

Psychoeducation

Telehealth intervention vs. usual care group

Duration: unclear

2 medium-term follow-ups: 3 and 6 months (post-baseline)

Subjective social isolation outcome: the informational support and emotional support subscales of the instrument that was developed by Krause and Markides [65]

No significant between-group difference on perceived social support (F (1,27) = 3.79, p = 0.062)

O’Mahen [55]—83 women aged > 18 with major depressive disorder (MDD)

Online in the UK (general population setting)

Psychoeducation and supported socialisation

Netmums Helping with Depression (HWD) vs. treatment-as-usual control group

Duration: unclear

End-of-treatment follow-up (unclear)

1 medium-term follow-up: 6 months

Subjective social isolation outcome: the Social Provision Scale [66]

Other outcomes: depressive symptoms; anxiety symptoms

No significant between-group difference in perceived support between the intervention and control group (95% CI 1.02, − 0.02), medium effect size = 0.50 (p = 0.27)

Interian [56]—103 veterans with PTSD

Online in the US (primary care setting)

Psychoeducation and changing cognitions

The Family of Heroes intervention vs. no-treatment control group

Duration: unclear

1 medium-term follow-up: 2 months (post-baseline)

Subjective social isolation outcome: the family subscale of the MSPSS [57]

Intervention group reported a higher chance of having a decreased perceived family support over time than the control group (p = 0.04)^f

^aEffect size, confidence interval and actual p value not available in the paper

^bConfidence interval and actual p value not available in the paper

^cEffect size, confidence interval and actual p value not available in the paper

^dEffect size and confidence interval not available in the paper

^eConfidence interval and actual p value not available in the paper

^fEffect size not available in the paper