Descriptive data
At the 13-year research clinic, 6529 participants completed the victimisation assessment. Characteristics of those reporting either no, occasional, or frequent victimisation are presented in Table 1. Individuals who reported frequent victimisation were more likely to report concurrent depressive symptoms in adolescence, and were more likely to have experienced maltreatment and emotional and conduct problems as a child compared to their non-victimised peers. Findings revealed no interaction between sex and peer victimisation (p = 0.44), therefore all analyses were carried out on the entire sample.
Of those who completed the victimisation measure, 3796 (58.1%) attended and completed the depression assessment at the 18-year research clinic, and 2521 provided information on the relevant confounding variables. 55.5% of these individuals with complete data were female, and 7.3% had a diagnosis of depression, of which 75% were female. Frequent victimisation was experienced by approximately 17.7% of this sample. Among those who also provided wellbeing data at age 23 (n = 1486), 63.5% were female and 16.1% reported frequent victimisation in adolescence. Of these individuals, 6.5% had a diagnosis of depression. Cases of depression were significantly more likely to be female (86.5%) but average mental wellbeing scores did not significantly differ between males (M = 50.0, SD = 8.52, range = 16–70.) and females (M = 49.39, SD = 8.64, range = 14–70).
Table 1
Sociodemographic and individual characteristics of participants by peer victimisation at 13 years. Values are means (standard deviations) unless stated otherwise.
|
No Victimisation (n = 3026)
|
Occasional Victimisation (n = 2360)
|
Frequent Victimisation (n = 1143)
|
p valuea
|
Individual Characteristics
|
|
Male (%)
|
50.5
|
47.1
|
47.2
|
0.03
|
Childhood emotional problems
|
1.4 (1.6)
|
1.5 (1.7)
|
1.6 (1.7)
|
< 0.001
|
Childhood conduct problems
|
1.4 (1.4)
|
1.5 (1.4)
|
1.7 (1.5)
|
< 0.001
|
Adolescent depressive symptoms
|
2.5 (2.6)
|
4.2 (3.5)
|
7.2 (5.0)
|
< 0.001
|
Adolescent bullying perpetration
|
0.2 (0.7)
|
0.8 (1.4)
|
2.1 (2.4)
|
< 0.001
|
Family Characteristics
|
|
Lower maternal social class, (%)
|
21.6
|
20.0
|
18.8
|
< 0.01
|
Maternal education: O levels or less (%)
|
58.5
|
54.9
|
54.4
|
0.04
|
Maternal depression
|
5.3 (3.7)
|
5.8 (3.9)
|
6.1 (3.8)
|
< 0.001
|
Maltreatment (%)
|
2.0
|
3.0
|
5.1
|
< 0.001
|
Note:
a p value reflects comparisons between non-victims and victims of frequent victimisation
|
Association Between Victimisation And Depression
Our first set of analyses were a replication of the previous study on the association between peer victimisation and depression [9]. Prior to conducting our logistic regression, we subset participants based on their victimisation status (none, occasional, frequent) and examined the proportion of individuals that were depressed. This allowed comparisons with previous estimates reported in this sample [9]. The presence of depression was shown to be higher among those exposed to more frequent experiences of victimisation. Around 15% of individuals who were frequently victimised as an adolescent were clinically depressed at age 18, compared to 5.6% of those not victimised. Such findings closely align with previous reports in this sample [9].
Logistic regressions examining the association between peer victimisation and depression revealed that the increased risk of depression corresponds to an odds ratio of 2.92 (95% confidence interval 2.17 to 3.93) compared to those who were not victimised (Table 2), with similar findings reported when using mother reports of victimisation (OR = 2.19, 95% confidence interval 1.14 to 3.86). These estimates are highly similar to the previous study [9], with previous reports showing that the increased risk of depression among those self-reporting frequent victimisation corresponds to an odds ratio of 2.96 (95% confidence interval 2.21 to 3.97) compared with those who were not victimised. After
adjusting for confounding variables, our analyses using self-reported victimisation were reduced to 1.87 (95% confidence interval 1.18 to 2.95), and the relationship was no longer significant using the maternal reports (OR = 1.80, 95% CI = 0.76 to 3.80), a finding that was also observed previously [9] Results using the imputed dataset showed a similar pattern of results across analyses (Table 2). It should be noted that estimates using both the complete case and imputed datasets vary slightly from previous analyses on this sample [9] due to changes in sample size and variables used for imputation.
Table 2: Odds ratios for depression at age 18 based on victimisation at age 13 years.
|
|
Unadjusted odd ratios (95% CI)
|
|
Odd ratios (95% CI)
|
Victimisation status
|
No (%) depressed
|
All available data (n = 3796)
|
Complete cases
(n = 2521)
|
|
Adjusted (n = 2521)a
|
Unadjusted using imputed datasetb
|
Adjusted using imputed datasetb
|
None
|
1734 (5.6)
|
1.00
|
1.00
|
1.00
|
1.00
|
1.00
|
Occasional
|
1409 (7.0)
|
1.26 (0.95–1.68)
|
1.11 (0.73–1.69)
|
0.86 (0.58–1.26)
|
1.14 (0.63–1.55)
|
1.03 (0.77–1.37)
|
Frequent
|
656 (14.9)
|
2.92 (2.17–3.93)
|
2.81 (1.95–4.59)
|
1.87 (1.18–2.95)
|
2.23 (2.10–3.98)
|
1.80 (1.22–2.43)
|
Note:
a Adjustments: children’s individual characteristics (sex, emotional and behavioural problems aged 7, concurrent depressive symptoms and concurrent bullying perpetration aged 13) and family characteristics (social class reported by mothers, mother’s education, maternal depression and child maltreatment experiences between the ages of 5 and 7).
b Missing confounders and additional sociodemographic variables used for imputation (n = 4040).
|
Association Between Victimisation And Wellbeing
To test the primary aim of our study, we subsequently explore associations between peer victimisation and adult wellbeing. The wellbeing of individuals who reported frequent victimisation during adolescence was found to vary depending on whether or not individuals received a diagnosis of depression at 18 years, t(63.37)= -4.5027, p < 0.001. Those who avoided a diagnosis of depression had significantly higher wellbeing at 23 years compared to those who reported depression at 18 years of age. Individuals who experienced frequent victimisation and avoided depression however, had significantly lower wellbeing than individuals with no experiences of either victimisation or depression, t(530.89)=- 3.9926, p < 0.001. These findings are represented in Fig. 1.
Linear regression models investigating a possible relationship between peer victimisation and wellbeing revealed that increases in experiences of victimisation are also associated with adult wellbeing. A one-point increase in frequent victimisation reported by the adolescent was associated with a 2.71 (SE = 0.46, p < 0.001) decrease in wellbeing scores (Table 3). Similar findings were found when using mother reports, with a one-point increase in victimisation associated with a 2.95 (SE = 1.06, p < 0.01) decrease in their child’s wellbeing aged 23. After adjustment for the confounding variables, associations remained significant using the maternal reports of victimisation but not the self-report measures.
To explore the potential mediating role of depression, analyses were repeated while controlling for depression diagnoses at age 18 (see model 3, Table 3). Findings revealed a set of highly similar results to analyses without depression as a confounder, suggesting that victimisation exerts a significant and direct impact on adult wellbeing. Analyses repeated using the imputed dataset revealed a similar pattern of results (see Supplementary Table 4, Additional File 5).
Finally, to test the robustness of the association between peer victimisation and adult wellbeing, in further analyses we adjusted for experiences of victimisation in adulthood. Although slightly attenuated, results were similar to findings without adult victimisation as a confounder. This was found using both the complete cases (see model 5, Table 3) and imputed datasets (see Supplementary Table 4). Such findings suggest that victimisation exerts strong longitudinal effects on adult wellbeing.
Sensitivity Analyses
Beyond these results for our overall measure of mental wellbeing, we conducted follow-up analyses using more specific wellbeing measures. Linear regressions using the Satisfaction with Life Scale [41] revealed the most consistent results to those found using the WEMWBS [39], with frequent victimisation associated with a 2.30 (SE = 0.34, p < 0.001) decrease in life satisfaction aged 23. Models that investigated wellbeing using the Subjective Happiness Scale [42] and the Basic Psychological Needs Scale [44] revealed a similar pattern of results, although findings using these scales were attenuated (see Supplementary Table 5, Additional File 6). When investigating the impact on meaning in life aged 23, it was found that this was not predicted by peer victimisation in adolescence.
Table 3: Linear regression results for wellbeing aged 23 years based on experiences of peer victimisation |
| | Occasional victimisation† | | Frequent victimisation†† |
| N | Estimate | SE | P value | R Squared | Estimate | SE | P value | R Squared |
Model 1 | | | | | | | | | |
Unadjusted model | 3015 | -1.04 | 0.36 | < 0.01 | 0.01 | -2.71 | 0.46 | < 0.001 | 0.01 |
Model 2 a | | | | | | | | | |
Adjusted for confounders only | 1882 | 0.08 | 0.45 | 0.85 | 0.08 | -0.83 | 0.67 | 0.21 | 0.08 |
Model 3 b | | | | | | | | | |
Adjusted for depression only | 2268 | -0.74 | 0.40 | < 0.05 | 0.04 | -2.28 | 0.53 | < 0.001 | 0.04 |
Model 4 a,b | | | | | | | | | |
Adjusted for depression and confounders | 1486 | 0.40 | 0.50 | 0.42 | 0.08 | -0.53 | 0.75 | 0.48 | 0.08 |
Model 5 c | | | | | | | | | |
Adjusted for adult victimisation only | 2558 | -0.90 | 0.38 | < 0.05 | 0.03 | -2.21 | 0.50 | < 0.001 | 0.03 |
Model 6 a,c | | | | | | | | | |
Adjusted for adult victimisation and confounders | 1631 | 0.18 | 0.47 | 0.71 | 0.08 | -0.44 | 0.72 | 0.54 | 0.08 |
Model 7 b,c | | | | | | | | | |
Adjusted for adult victimisation and depression | 1937 | -0.58 | 0.42 | 0.17 | 0.04 | -1.94 | 0.57 | < 0.001 | 0.04 |
Model 8 a,b,c | | | | | | | | | |
Adjusted for adult victimisation, depression and confounders | 1289 | 0.38 | 0.52 | 0.47 | 0.08 | -0.46 | 0.80 | 0.57 | 0.08 |
Note: a Adjustments: children’s individual characteristics (sex, emotional and behavioural problems aged 7, depressive symptoms and bullying perpetration aged 13, employment status and income aged 23) and family characteristics (social class reported by mothers, mother’s education, maternal depression and child exposure to physical or sexual abuse aged 7). b Adjustments: depression diagnoses from the CIS-R at 18 years. c Adjustments: peer victimisation at 23 years. † Estimates relate to the impact of occasional victimisation on wellbeing aged 23 †† Estimates relate to the impact of frequent victimisation on wellbeing aged 23 |