Of the five treatments studied in primary care, a meta-analysis on CBT yielded a significant result, indicating its potential benefit in primary care settings. There was also a positive effect with bright-light therapy, and although this is promising, it needs replication in a second trial in primary care before recommendations for implementation can be made. Unfortunately, we did not find convincing evidence in favor of exercise, PST, or behavioral activation for the treatment of depressive symptomatology in primary care, but better quality research is needed before we can reach any definitive conclusions. In addition, community-based studies showed promising short-term results for bibliotherapy, life-review, PST, behavioral therapy, brief psychodynamic therapy, and cognitive therapy, which might, therefore, be suitable for use as treatment strategies in primary care.

Comparison with existing literature

Previous systematic reviews and meta-analyses focusing on the use of non-pharmacological treatment for depression in older patients have reported different findings to those in our review [17–20]. Two recent systematic reviews [18,20], for example, concluded that psychological treatments may be feasible for late-life depression (65+), but they did not perform formal meta-analyses. However, both of these reviews questioned the generalizability and efficacy because of the wide diversity of interventions, the low number of studies per intervention, and the poor quality of studies included. Moreover, neither review was limited to the primary care setting, and studies were excluded if they had a low quality assessment, leading to the exclusion of 73.9% [18] and 36.4% [20] of the identified studies, respectively. To be more comprehensive, we decided not to restrict ourselves to RCTs and not to exclude studies based on the quality assessment. This not only ensured that we could summarize all available evidence but also enabled us to formulate explicit targets for future research, such as instances where an included study was of poor quality but focused on a promising intervention.

Another two reviews included formal meta-analyses of the research [17,19], and they indicated that psychological treatments were moderately effective in the treatment of late-life depression. Specifically, one showed that CBT, life-review, and PST [17] were effective, while the other showed that CBT was more effective than a non-active control group [19]. However, these meta-analyses included studies conducted in clinical settings and with middle-aged participants (50/55+). These differences might explain why we could not replicate the finding that PST was an effective treatment for late-life depression in primary care; also, it should be noted that life-review therapy has been studied as treatment for late-life depression in primary care to date. Nonetheless, we confirmed the positive results for life-review and PST on depressive symptoms in community settings. We could also replicate the finding that CBT was an effective treatment modality for late-life depression at 6 months’ follow-up, though with a small effect size (SMD -0.21 [-0.40 to -0.03]) comparable to that reported in one of the previous studies [17]. The other meta-analysis demonstrated a much larger effect size (-1.35) when CBT was compared with inactive controls, but did not find an effect when comparing CBT to active controls [19]. The fact that we analyzed the effect of CBT compared with both active and inactive controls might explain this difference. Although one might question the clinical relevance of this small effect of CBT, it might be partly caused by a floor-effect of treatment associated with milder forms of depression as seen and treated within primary care.

Another systematic review found that physical exercise may be effective for late-life depression [56]. We could not replicate this finding, irrespective of the quality assessments of these studies, but it should be noted that the previously conducted review included studies recruiting non-depressed adults, and that none of the studies included in the earlier review [56] was conducted in a primary care setting.

Several differences can be seen when comparing the studies conducted in primary care with those conducted in the community. First, although more treatment modalities have been studied in community settings, it is questionable whether these treatment modalities are applicable in general practice. For example, creating a life-story book with personalized pictures [35] is overly time-consuming for most GPs or practice nurses. Second, the follow-up periods of the community-based studies were shorter than those conducted in primary care. Because none of the studies included a control condition beyond the assessment when treatment ended, no data is available on the sustainability of the effects. Third, most of the community studies only included self-referred participants, thereby introducing selection bias. Self-referred participants show the initiative to seek out interventions targeting depression, whereas in general, depressed older adults are more likely to be reluctant to seek help [57]. This purported selection bias might also explain some of the low percentages lost to follow-up in the self-referral studies performed in the community. Although it is conceivable that community-based interventions would also be effective in primary care, further research is needed to confirm this assumption. Finally, among the therapist-guided interventions, almost half were delivered by a postgraduate therapist or clinical psychologist in the community studies, while only one-third included a psychologist in the primary care studies. Because it is questionable whether clinical psychology services could be successfully embedded in general practice, due for example to higher costs for patients and/or insurances, future research should determine whether these interventions can be successfully given by a practice nurse or other allied healthcare professionals.

Several non-pharmacological treatments for late-life depression studied a community setting seem promising for implementation in primary care. First of all, PST demonstrated a beneficial effect in the community [36,41,42], but the only RCT conducted in primary care demonstrated no effect on depressive symptoms [34]. However, the risk of bias was lower in two of the community studies [36,42] compared with the study conducted in primary care [34], and among middle-aged adults the effectiveness of PST in primary care has been confirmed [58]. Due to the positive results of PST in the community setting and among middle-aged adults, we recommend a second RCT in primary care focusing on PST with a longer follow-up duration than the study included in our review (11 weeks) [34]. Moreover, the control group in this primary care study [34] existed of paroxetine or a placebo, while an attention control form of therapy would have been more adequate. Furthermore, bibliotherapy [37,44,47,48] and life-review [35,45,50] have demonstrated beneficial effects in community settings, although follow-up duration was short (maximum of 8 weeks). Before implementation in primary care, life-review and bibliotherapy need to be studied among primary care patients with a longer follow-up duration. Furthermore, these studies had some issues regarding their risk of bias, with a high risk of bias for the bibliotherapy studies [37,44,47,48] and a moderate risk of bias for two of the life-review studies [35,45], and these concerns need to be addressed in a future RCT conducted in primary care. Finally, the effect of behavioral activation therapy seems promising in a pilot cohort study conducted in primary care [26], and is currently being investigated in a well-designed RCT in primary care [59]. In addition to this latter RCT, also PST, bibliotherapy, and life-review should be studied in a RCT in primary care among depressed patients confirmed by a diagnostic interview and with at least a one-year follow-up.