Further trials and reviews we read, including ones in Africa and ones with weaker or mixed results.
Lay providers in KenyaRandomised trial
In Kenya, a four-session group programme led by trained lay providers reduced adolescent depression and anxiety more than a study-skills control.
In four Nairobi and Kiambu schools, 413 adolescents aged 13 to 18 with elevated symptoms had four weekly group sessions led by lay providers aged 18 to 26 who had 10 hours of training. Compared with a study-skills group, depression improved by d 0.35 and anxiety by d 0.37 at 4 weeks, and by d 0.45 and d 0.44 at 7 months.
Limits
- Only 54% of participants completed the 7-month assessment.
- The control group also improved.
- The programme developers are affiliated with the funder and ran the trial.
- The depression measure omits the suicide item.
Guided digital supportRandomised trial
In Lebanon, a WHO digital behavioural-activation programme with weekly non-specialist contact reduced depression among Syrian refugees.
In a trial of 569 displaced Syrians with depression, the Step-by-Step programme, delivered by app or web with up to 15 minutes of weekly phone or message contact from a non-specialist, reduced PHQ-9 depression scores more than enhanced care as usual (g 0.48, 95% CI 0.26 to 0.70 after treatment, and g 0.61 at three months).
Limits
- Only 53.8% returned the post-test questionnaire and 32.2% of the intervention group completed all sessions.
- The article’s own attrition figures are inconsistent, and a correction was published in 2023.
- The trial ran in Lebanon with a displaced population, not in East Africa.
A chatbot trial in AfricaRandomised trial
In Malawi, a scripted CBT chatbot reduced depression scores among health workers. The anxiety result was not statistically significant.
In an eight-week trial among health workers in Blantyre and Lilongwe, the Vitalk chatbot reduced PHQ-9 depression scores more than a passive resource page (difference-in-differences −0.68, 95% CI −1.15 to −0.21). The anxiety difference (−0.44, 95% CI −0.88 to 0.01) included zero.
Limits
- Retention was 29% in the chatbot group and 40% in the control group, and the analysis used complete cases.
- The Malawi version had no natural language understanding, so it was not a generative AI companion.
- Participants were health workers, not the general public, and the control group was waitlisted.
- The authors’ causal wording goes further than the design supports.
An early conversational CBT trialRandomised trial
An early trial of a rule-based CBT chatbot found lower depression scores after two weeks than an information-only control.
In a 2017 trial of 70 US college students with symptoms of depression and anxiety, two weeks of the Woebot chatbot lowered PHQ-9 scores more than an information ebook (d 0.44). There was no between-group difference in anxiety (d 0.14).
Limits
- The trial was unblinded, small and had no follow-up.
- The control was information only, so the trial cannot separate conversational delivery from CBT content.
- One author founded the company that made the chatbot.
Chatbot trials, pooledMeta-analysis
A 2025 meta-analysis of 31 trials found small to moderate effects of AI chatbots on distress in people aged 15 to 39, with generative systems still inconclusive.
The review pooled randomised trials of AI chatbots in people aged 15 to 39 (31 trials, 29,637 participants). Mental distress fell by SMD −0.35 (95% CI −0.46 to −0.24), depressive symptoms by −0.43 and anxiety by −0.37. Retrieval-based systems had consistent effects. For generative systems the authors judged the overall effectiveness inconclusive.
Limits
- We read the published abstract, not the full paper.
- The age range is 15 to 39. It does not cover older adults.
- The authors call for safety protocols and evaluation frameworks for generative systems.
Generative AI chatbots, pooledMeta-analysis
A 2025 meta-analysis of 14 trials of generative AI chatbots found a pooled effect of 0.30, with a wide margin of uncertainty.
The review pooled 14 randomised trials (6,314 participants) of generative AI chatbots and found a pooled effect of 0.30 (95% CI 0.004 to 0.59; 95% prediction interval −0.85 to 1.67).
Limits
- The interval runs from almost no effect to a large one, and the prediction interval includes both harm and benefit.
- The protocol was registered after the review began.
- With 14 trials, the finding that social-oriented chatbots outperformed task-oriented ones is exploratory.
- We read the abstract, not the full paper.