ADHD in adulthood is commonly associated with internalising symptoms, including mood and anxiety disorders (Kessler et al. 2006). Non-pharmacological treatments such as cognitive behavioural therapy (CBT), cognitive training (CT), cognitive hypnotherapy, dialectical behavioural therapy (DBT), mindfulness-based therapies (MBTs), neurofeedback (NFB) and psychoeducation (PsyEd) have been evaluated in adults with ADHD. These therapies have had mixed success in reducing internalising symptoms in adults with ADHD. This meta-analytic review aimed to evaluate the efficacy of these different non-pharmacological interventions (specifically adapted or developed to address the core symptoms of ADHD in adults) for treatment of comorbid internalising symptoms (depression and anxiety symptoms, low self-esteem, impaired perceived quality of life [QoL] and emotional dysregulation [ED]). This study also sought to investigate if the effect of treatment on core ADHD symptoms could predict improvements on comorbid internalising symptoms.
A literature search* was conducted to identify studies with ≥1 experimental group receiving a non-pharmacological intervention specifically designed or modified for treating adult ADHD. From 1054 study records, 20 randomised control trials (RCTs), three controlled pre-test–post-test studies and 12 uncontrolled single-group pre-test–post-test studies were selected.† A total of 1389 study participants were randomised across the RCTs examined; among these, data were collected from 1163 participants post-treatment and from 629 participants at follow-up. Across the uncontrolled studies selected, 634 participants were initially included in the pre–post studies, 521 were maintained at post-treatment and 219 at follow-up. Participants were mostly male (51.85%), mean age was 34.16 years, and 54.79% of participants were taking medication for ADHD.
Overall, 41.67% of participants had CBT (n = 15), 16.67% had DBT and MBT (n = 6 each), 13.89% had NFB (n = 5), 5.56% had CT (n = 2), and 2.87% had hypnotherapy or PsyEd (n = 1). The average length of the interventions was 12.34 sessions. Treatments were given in either group (48.47%) or individual (36.36%) sessions, or as a combination of both (15.15%). Self-reported measures were most commonly used to assess efficacy, although blinded (3.12%) and un-blinded (10.91%) independent assessors were used in some studies.
- CBT had a small-to-moderate effect size (ES) on depression symptoms in participants with ADHD compared with control groups post-treatment (standardised mean difference [SMD] 0.27; 95% confidence interval [CI] 0.02–0.52; I2 = 52%) and a moderate-to-large ES when post-test results were compared with pre-test results (within-subject comparison: SMD 0.54; 95% CI 0.35–0.72; I2 = 72%). At follow-up, a moderate-to-large ES was reported on depression symptoms between groups (SMD 0.52; 95% CI 0.24–0.80; I2 = 0%), and was maintained on the within-subject outcome (SMD 0.72; 95% CI 0.48–0.96; I2 = 42%).
- At post-treatment, the ES of CBT intervention on anxiety symptoms was small-to-moderate for between-group (SMD 0.31; 95% CI 0.01–0.62; I2 = 64%) and within-subject outcomes (SMD 0.49; 95% CI 0.25–0.72; I2 = 82%) but increased to moderate-to-large at follow-up for both between-group (SMD 0.73; 95% CI 0.45–1.02; I2 = 0%) and within-subject outcomes (SMD 0.74; 95% CI 0.28–1.21; I2 = 84%) at follow-up.
- CBT did not have a significant effect on self-esteem when control and treatment groups were compared; however, a small-to-moderate post-treatment within-subject ES (SMD 0.62; 95% CI 0.31–0.92; I2 = 80%) increased to large at follow-up (SMD 1.404; 95% CI 0.45–1.64; I2 = 74%).
- The ES on QoL at post-treatment was small-to-moderate for within-subject outcomes (SMD 0.28; 95% CI 0.09–0.48; I2 = 80%) but increased to moderate-to-large at follow-up (SMD 0.57, 95% CI 0.22–0.92).
- Similarly, the within-subject treatment effect on ED increased from small-to-moderate at post-treatment (SMD 0.38; 95% CI 0.16–0.60; I2 = 0%) to moderate-to-large at follow-up (SMD 0.73; 95% CI 0.42–1.03; I2 = 80%).
- A small-to-moderate post-treatment within-subject effect on depression symptoms (SMD 0.36; 95% CI 0.24–0.48; I2 = 33%) was maintained at follow-up (SMD 0.33; 95% CI 0.13–0.53; I2 = 63%). No significant effect on depression symptoms was observed between control and treatment groups.
- DBT did not have a significant effect on anxiety.
- A significant within-subject effect of treatment on self-esteem was only observed at follow-up (SMD 0.48; 95% CI 0.34–0.63; I2 = 2%).
- Compared with an active control group, a large ES on QoL was obtained after treatment (SMD 0.84; 95% CI 0.25–1.43) but was not sustained at follow-up.
- A moderate-to-large ES reported on QoL for within-subject outcomes at post-treatment (SMD 0.61; 95% CI 0.06–1.16; I2 = 73%) decreased to small-to-moderate at follow-up (SMD 0.40; 95% CI 0.17–0.64; I2 = 0%).
- The within-subject ES on depression symptoms was small-to-moderate for within-subject outcomes at post-treatment (SMD 0.33; 95% CI 0.17–0.50; I2 = 31%) but was null at follow-up.
- No significant effect was observed on comorbid depression and anxiety symptoms between control and treatment groups, nor in the within-subject anxiety group.
- A large ES was observed on within-subject QoL outcomes post-treatment (SMD 1.44; 95% CI 0.85–2.03).
- At post-treatment, the ES of MBT on ED was small-to-moderate for within-subject outcomes (SMD 0.44; 95% CI 0.28–0.61; I2 = 22%) and also when the treated group was compared with waiting list controls (SMD 0.46; 95% CI 0.15–0.76; I2 = 0%).
- A large ES on comorbid depression symptoms was observed for within-subject outcomes at post-treatment (SMD 0.85; 95% CI 0.62–1.08; I2 = 10%), which decreased to moderate-to-large at follow-up (SMD 0.65; 95% CI 0.43–0.86; I2 = 0%).
- A moderate-to-large ES on anxiety for within-subject comparisons at post-treatment (SMD 0.72; 95% CI 0.23–1.12; I2 = 80%) increased to large at follow-up (SMD 0.85; 95% CI 0.59–1.10; I2 = 10%). The effect on anxiety and depression symptoms was not significant when comparing NFB with control groups.
- A small-to-moderate ES of NFB on self-esteem was observed on within-subject comparisons at post-treatment (SMD 0.47; 95% CI 0.06–0.88) increased to moderate-to-large at follow-up (SMD 0.68; 95% CI 0.19–1.17).
- When compared with an active control group, the between-group effect on self-esteem increased from null after treatment to moderate-to-large at follow-up (SMD 0.70; 95% CI 0.09–1.31).
- Only non-significant ESs were reported for CT interventions.
- Only non-significant ESs were reported for hypnotherapy interventions.
- A null ES was obtained on within-subject self-esteem outcome after treatment.
ES on core ADHD symptoms
Data from all studies were merged to investigate if a treatment’s effect on core symptoms was linked to improvement on internalising symptoms.
- At post-treatment, a greater ES on core ADHD symptoms significantly positively correlated with treatment efficacy on:
- Depression (between-group coefficient = 0.27, 95% CI 0.13–0.42, p < 0.01; within-subject coefficient = 0.31, 95% CI 0.04–0.57, p < 0.01)
- Anxiety (between-group coefficient = 0.49, 95% CI 0.17–0.82, p < 0.01; within-subject coefficient = 0.31, 95% CI 0.04–0.57, p = 0.02)
- Self-esteem (between-group coefficient = 0.41, 95% CI 0.20–0.62, p < 0.01; within-subject coefficient = 0.41, 95% CI 0.13– 0.70, p < 0.01).
- At follow-up, a greater ES on core ADHD symptoms significantly positively correlated with treatment efficacy on:
- Depression (between-group coefficient = 0.31, 95% CI 0.04–0.57, p < 0.01)
- Anxiety (between-group coefficient = 0.57, 95% CI 0.19–0.95, p < 0.01; within-subject coefficient = 0.60, 95% CI 0.10–1.09, p = 0.02).
- Regressions were not significant for QoL and ED outcomes.
This study had several limitations. Firstly, PsyEd and hypnotherapy interventions were each only examined in one study with a small sample size (n = 9). Secondly, variations in study design and sample size may limit the appropriateness of direct comparison of efficacy of these studies. Thirdly, the small number of studies in some subgroups could limit the statistical power of the analyses used to identify predictors of improvements on internalising symptoms. Fourth, merging all of the therapy modalities may have limited the findings regarding how these variables may influence the effect of each intervention. Fifth, there were a small number of studies that compared the treatment with active control groups, which may limit the specificity of the psychotherapies assessed. Sixth, the inclusion of uncontrolled studies may impair internal validity, as this impacts on the control of other variables and could influence the observed effects. Finally, the generalisability of these findings may be limited due to the high heterogeneity observed in some post-treatment outcomes.
The authors concluded that this systematic review offers support for the efficacy of non-pharmacological treatment, notably CBT, in treating comorbid internalising symptoms in adults with ADHD. CBT achieved better improvements in comorbid anxiety and depression symptoms, as well as long-term QoL and ED outcomes compared with waiting list and treatment-as-usual groups. The authors advocated the use of these therapies as part of comprehensive treatment of adult ADHD.
*The databases Scopus, PsycINFO and MEDLINE were searched by terms relating to adult ADHD, CBT, DBT, neurofeedback and MBT. The following terms where used in the title and abstract: adult*, ADHD OR attention deficit hyperactivity OR psychosocial t* OR skills train*, CBT OR cognitive behavio, DBT OR dislectical behavio, neurofeedback, MBCT OR mind-ful*. The last search was performed on 20 October 2018
†Studies with participants aged ≥18 years with a primary diagnosis of ADHD made by a mental health professional (either in the community or by a member of the study research team) on the basis of a full clinical interview and ADHD rating scales were included. Studies with participants with severe active addictions, bipolar, psychotic or personality disorders were excluded from the analysis. RCTs with an active control group (e.g. participants were given support by a therapist but no specific strategy was discussed, non-specific interventions for ADHD such as relaxation OR sham NFB may be used); or a treatment-as-usual control group (all participants received ADHD medication and perhaps some counselling or clinical management, provided no specific strategy was discussed); or a waiting list control group (participants were waiting without receiving a non-pharmacological intervention) were eligible for inclusion. Uncontrolled single-group pre-test–post-test studies were also included
López-Pinar C, Martínez-Sanchís S, Carbonell-Vayá E, et al. Efficacy of nonpharmacological treatments on comorbid internalising symptoms of adults with attention-deficit/hyperactivity disorder: a meta-analytic review. J Atten Disord 2020; 24: 456-478.
Kessler RC, Adler L, Barkley R, et al. The prevalence and correlates of adult ADHD in the United States: results from the National Comorbidity Survey Replication. Am J Psychiatry 2006; 163: 716-723.