Abstract

This conceptual analysis synthesizes patient-level participation barriers described in the bipolar disorder CBT literature and considers ketogenic metabolic therapy (KMT) as a candidate adjunct within a delivery-focused framework. CBT is an evidence-based adjunctive psychotherapy for bipolar disorder, but its clinical value depends on whether patients initiate treatment, sustain session continuity, and complete between-session practice that supports skill use in daily life. In routine care, psychotherapy uptake remains limited, discontinuation can occur early, and patient-level barriers can constrain delivered dose. Early clinical evidence for KMT in bipolar disorder remains preliminary and does not support conclusions regarding disorder-level efficacy or comparative effectiveness. Case reports, retrospective analyses, and pilot trials describe KMT-associated change in domains that overlap with capacity for CBT participation, including mood stability, sleep, energy, anxiety, cognition, and functioning. To date, no studies have directly tested whether KMT improves CBT participation outcomes (initiation, continuity, or between-session practice) in bipolar disorder. This article presents a participation-capacity framework that evaluates KMT as an adjunct to guideline-consistent care and operationalizes research priorities for measuring participation, feasibility, and fidelity across psychotherapy dose, between-session practice, and verified ketosis, rather than symptom change alone. The model specifies sequential decision points for introducing KMT before CBT when participation capacity limits initiation or early continuity, or after participation barriers emerge. CBT is initiated or resumed when pre-specified participation-readiness indicators suggest that an adequate CBT dose can be delivered.

1 Introduction

Bipolar disorder (BD) is a recurrent disorder typically managed with pharmacotherapy, with contemporary treatment guidance emphasizing adjunctive psychosocial interventions as part of comprehensive care (Yatham et al., 2018; Keramatian et al., 2023). Within guidance from the Canadian Network for Mood and Anxiety Treatments (CANMAT) and the International Society for Bipolar Disorders (ISBD), structured psychosocial interventions are recommended as adjuncts to medication for relapse prevention and functional recovery (Oud et al., 2016; Yatham et al., 2018; Miklowitz et al., 2021; Keramatian et al., 2023). Psychoeducation is supported for relapse prevention during euthymia, and cognitive-behavioral therapy is positioned as an adjunctive option for acute bipolar depression and for maintenance treatment, with no recommendation for acute mania due to insufficient evidence in that phase (Chiang et al., 2017; Yatham et al., 2018; Keramatian et al., 2023).

Cognitive-behavioral therapy (CBT) for BD is a manualized psychotherapy that targets illness management skills for relapse prevention and depressive symptom management (Yatham et al., 2018). Evidence syntheses support mild-to-moderate effects when CBT is added to standard care, including reduced relapse, improved depressive symptoms, reduced mania severity, and improved psychosocial functioning in pooled randomized trial analyses (Chiang et al., 2017). Comparative syntheses of adjunctive manualized psychotherapies also support lower recurrence rates than control conditions, with CBT associated with stabilization of depressive symptoms at 12 months compared with treatment as usual (Miklowitz et al., 2021). Aggregate and individual patient data meta-analyses focused on bipolar depression similarly support psychological interventions as relevant to depressive symptom reduction, with findings most interpretable for CBT while also noting heterogeneity and limitations in evidence quality (Yilmaz et al., 2022, 2025b). Consistent with this evidence base, CBT is recommended as a second-line adjunctive treatment for acute bipolar depression and as a second-line option for maintenance in selected patients, with no recommendation for CBT in mania due to insufficient evidence (Yatham et al., 2018; Keramatian et al., 2023).

Despite guideline endorsement and evidence of benefit, psychotherapy remains underused in bipolar depression, and barriers to access and implementation mean that adequate delivery of evidence-based CBT cannot be assumed in routine care (Yatham et al., 2018; Chiang and Miklowitz, 2023). Attrition occurs even in structured CBT programs for bipolar disorder, with premature discontinuation limiting delivered dose (Jones et al., 2015; Docteur et al., 2018; Hautzinger and A2 BipoLife Consortium, 2024). In community settings, clinicians identify comorbid substance use disorders and treatment adherence difficulties as prominent barriers that interfere with optimal care delivery (Stein et al., 2015). Together, these findings support a delivery-focused framing in which CBT benefit depends on whether individuals can initiate and sustain sufficient participation for CBT to be delivered as intended (Docteur et al., 2018; Chiang and Miklowitz, 2023).

Ketogenic metabolic therapy (KMT) is a clinician-supervised ketogenic dietary intervention designed to induce nutritional ketosis and is increasingly discussed within metabolic psychiatry frameworks for serious mental illness, including mood disorders (Sethi and Ford, 2022; Rog et al., 2024). In BD, clinical literature has expanded from case-level reports (Yaroslavsky et al., 2002; Phelps et al., 2013; Saraga et al., 2020; Chmiel, 2022; Danan et al., 2022; Laurent, 2024; Schreel et al., 2025) to pilot studies supporting feasibility and acceptability and indicating the need for randomized controlled trials, including a BD-specific pilot and a pilot trial that enrolled participants with bipolar disorder alongside schizophrenia (Needham et al., 2023; Sethi et al., 2024). This conceptual analysis positions KMT as a candidate adjunct to CBT delivery in BD by framing whether KMT can reduce participation-limiting factors enough to increase CBT initiation, retention, and completion, with success defined in psychotherapy terms and KMT conceptualized as adjunctive rather than a replacement for established guideline-based BD treatments.

2 Positioning ketogenic metabolic therapy within CBT engagement and retention in bipolar disorder

Preclinical and mechanistic literature provides biological plausibility for investigating KMT in bipolar disorder. Animal and cellular work in mood-relevant models suggests that ketogenic states can alter pathways implicated in bipolar illness, including neuronal excitability, neuroinflammatory signaling, mitochondrial energy metabolism, and inhibitory to excitatory neurotransmitter balance, supporting a rationale for translational study without establishing clinical efficacy (Guan et al., 2020; Norwitz et al., 2020; Yu et al., 2023; Chrysafi et al., 2024; Freyberg et al., 2025). In parallel, theoretical frameworks in metabolic psychiatry propose bipolar-relevant models of dysregulated energy utilization and related ionic and circuit-level instability, positioning ketosis as a testable metabolic contrast within bipolar pathophysiology (Campbell and Campbell, 2024; Campbell et al., 2025). Against this backdrop, direct clinical evidence for KMT in bipolar disorder is drawn primarily from case reports, retrospective case series, and early feasibility and pilot trials. These reports describe KMT implementation and associated psychiatric outcomes in domains that may be relevant to CBT engagement, homework completion, and between-session follow-through, including mood stability, sleep, energy, anxiety, cognition, and functioning (Table 1).

An inpatient case report described an attempted ketogenic diet intervention in a treatment-resistant patient with rapid-cycling bipolar I disorder. The report described 4 weeks of diet implementation during hospitalization, with adherence rated as very good, and it noted no clinical improvement over the intervention period. The authors indicated that the intended ketogenic intervention was not successfully established during the admission and ketosis was not confirmed, limiting outcome interpretation (Yaroslavsky et al., 2002).

In a two-case report of bipolar II disorder, the report described a 69-year-old woman who had achieved partial benefit on medication but continued to experience residual depressive burden and prominent irritability, with dose escalation limited by side effects. After initiating a ketogenic diet, she reported improved mood stability and a marked reduction in agitation and “hair-trigger” reactivity, describing a sustained shift in how she responded emotionally to stressors and day-to-day frustrations, with benefits centered on steadier mood and improved behavioral control in daily life (Phelps et al., 2013). In the same report, a 30-year-old woman with bipolar II disorder with onset in adolescence reported adverse reactions to prior antidepressant trials, including increased suicidality, and later achieved sufficient stability with medication to sustain employment and a stable relationship. She initially adopted a ketogenic diet during flares of gastrointestinal symptoms and noticed that her mood felt calmer while in ketosis. Later, when she discontinued medication in preparation for pregnancy, she returned to the ketogenic diet, reported that mood symptoms resolved within days of achieving ketosis, and described sustained stability over multiple years during continued dietary implementation (Phelps et al., 2013).

A forum-based observational study analyzed free-text posts from individuals who self-reported bipolar disorder and described mood effects of dietary interventions. Reports of significant mood stabilization or symptom remission over time were substantially more common among those describing a ketogenic diet. In addition to mood stability, the analysis identified posts reporting fewer depressive episodes, fewer manic episodes, improved clarity of thought and speech, increased energy, reduced anxiety or panic attacks, and improved sleep. The authors emphasized that these findings were derived from self-reported public forum posts and should be interpreted cautiously (Campbell and Campbell, 2019).

A single case report described ketogenic diet use in bipolar I disorder that was self-initiated at home. The report described a 60-year-old woman with bipolar I disorder and a long history of mixed episodes with psychotic symptoms, who began a ketogenic diet after prior intensive psychotherapy. During follow-up, the clinical narrative reported decreased anxiety and maintenance of euthymia despite markedly stressful life events. The patient reported improved capacity to use her psychotherapy tools when difficulties arose. Brief mood dysregulations were described as shorter and less impairing than prior patterns (Saraga et al., 2020).

A subsequent case report described a male patient with bipolar disorder and ultra-rapid cycling who adopted a ketogenic dietary approach after persistent mood instability despite prior treatment. During multi-year follow-up, the report described the absence of hypomanic episodes and substantial improvement in depressive symptoms, with depressive periods becoming shorter and less severe. The narrative also noted improved sleep quality and improved cognitive functioning, including improved concentration (Chmiel, 2022).

A retrospective inpatient analysis examined adults with severe, persistent mental illness treated in a psychiatric hospital setting who received a ketogenic diet as an adjunct to standard inpatient care. 13 of the 31 patients were diagnosed with bipolar II disorder. In this subgroup, clinician-rated depressive symptom burden and global illness severity improved from pre- to post-intervention, consistent with reduced depressive symptoms and improved overall clinical status during hospitalization, within a structured clinical setting in which symptom change was tracked using established rating scales (Danan et al., 2022).

A single-arm prospective pilot study evaluated the feasibility, safety, and preliminary clinical signals of a 6 to 8 week modified ketogenic diet intervention in clinically euthymic adults with bipolar disorder delivered with structured dietetic support. Feasibility outcomes and process evaluation were reported in the initial publication, including daily ecological momentary assessment of anxiety, mood, energy, impulsivity, and speed of thought and participant feedback describing perceived improvements in mood, energy, and self-control during the intervention (Needham et al., 2023). A subsequent publication from the same cohort reported secondary clinical and daily rating findings, including associations between higher ketone levels and better day to day mood and energy with lower anxiety and impulsivity, and noted that seven of 20 completers declined the planned diet cessation period and opted to continue the ketogenic diet (Campbell et al., 2025). In a further publication from the same intervention, a mixed methods process evaluation examined feasibility, acceptability, and implementation using semi-structured post-intervention interviews with participants and intervention clinicians alongside descriptive analysis of fidelity checklists capturing behavior change components. Participants reported perceived psychological benefits, including greater mood stability, improved ability to focus, and improved capacity to tolerate stressors (P. Rigby et al., 2025).

A retrospective single-case study examined a woman with bipolar II disorder and longstanding treatment-resistant depressive symptoms. At the time of diet implementation, psychiatric intervention included weekly ketamine treatments that provided only short-lived relief, with benefits lasting 1 to 3 days before symptoms returned. KMT was delivered with clinician supervision and structured education. Over a 21-week period, the report described normalization of depressive and anxiety symptom scores alongside improved daily functioning and quality of life, and the case narrative and qualitative analysis emphasized greater energy, reduced fatigue, and improved capacity to manage everyday demands (Laurent, 2024).

A 4-month single-arm outpatient pilot trial enrolled adults with bipolar disorder or schizophrenia who continued their usual psychiatric treatment while receiving structured ketogenic diet support and monitoring. Among those who completed the study, overall clinical severity ratings improved over the intervention period, alongside improved sleep quality, improved life satisfaction, and improved global functioning. In subgroup analyses, bipolar participants showed improvement on overall severity ratings with a higher proportion rated as recovered on mood monitoring by study end (Sethi et al., 2024).

An outpatient case series reported seven individuals with bipolar disorder (four with bipolar II and three with bipolar I) who completed a 3-month ketogenic intervention while psychiatric treatment remained unchanged. Across the seven cases, the authors described improvement across all psychiatric assessments in 5 participants, while one case showed mixed changes and was not considered an unequivocal responder and one was characterized as a non-respondent. Global bipolar illness severity improved in five, was unchanged in one, and worsened in one. Depressive symptom measures generally improved across the series, alongside patient reports that included increased energy and emotional resilience or steadier mood in two cases and improved mental focus with better occupational functioning in one case (Schreel et al., 2025).

Across these case reports, retrospective series, and early pilot studies, the evidence base for KMT in bipolar disorder remains inconclusive and does not yet support broad conclusions regarding disorder level efficacy or comparative effectiveness (Rog et al., 2024). This early literature does however, describe consistent patient experiences across most case reports and trials, including improved mood stability, sleep regulation, reduced anxiety, improved cognitive function, increased energy, and improved day-to-day functioning, including among individuals with complex comorbidity and treatment-resistant illness (Phelps et al., 2013; Saraga et al., 2020; Chmiel, 2022; Danan et al., 2022; Needham et al., 2023; Laurent, 2024; Sethi et al., 2024; Schreel et al., 2025). These findings do not by themselves establish improved participation capacity; rather, they identify domains that are clinically relevant to patient-level factors reported to shape engagement, retention, and delivered dose of effective psychotherapy treatment.

3 Patient-level barriers to CBT engagement, homework and follow-through in bipolar disorder

A delivery-focused framing requires specifying what counts as participation in CBT for bipolar disorder. Participation includes initiation of treatment, continuity of attendance across the intended course, and completion of between-session tasks that extend the active ingredients of CBT into daily life (Miklowitz et al., 2021). CBT protocols for bipolar disorder commonly rely on repeated practice of monitoring, planned behavior change, and relapse prevention skills (ÖZDEL et al., 2021). Clinical benefit depends on a sustained dose of treatment delivered over time rather than isolated sessions (Chiang and Miklowitz, 2023). Evidence syntheses support that adjunctive CBT produces benefit in bipolar disorder when delivered as intended, while also underscoring that psychotherapy effects are contingent on sufficient engagement and retention (Oud et al., 2016; Chiang et al., 2017; Miklowitz et al., 2021). Psychotherapy participation in bipolar depression is constrained by underuse, limited uptake, and premature discontinuation in routine care, and adequate CBT delivery cannot be assumed outside research settings (Docteur et al., 2018; Miklowitz et al., 2021; Chiang and Miklowitz, 2023). Even in structured CBT trials for bipolar disorder, some participants do not complete the full intervention (Chiang et al., 2017), and early discontinuation can limit the delivered dose (Jones et al., 2015; Docteur et al., 2018).

Patient-level barriers to CBT engagement refer to clinical, cognitive, motivational, and social factors that interfere with initiation, session continuity, and completion of between-session practice (Stein et al., 2015; Hanssen et al., 2020; Chiang and Miklowitz, 2023). In bipolar disorder, these barriers commonly include depressive symptoms associated with low energy and reduced concentration (Hanssen et al., 2020). They also include hypomanic or manic symptoms (Hanssen et al., 2020) that disrupt continuity, limited insight and inaccurate self-appraisal (Grover et al., 2023; Wels et al., 2023), comorbid substance use and adherence difficulties (Stein et al., 2015), and limited social stability and support that undermine follow-through (Veseth et al., 2017).

Cognitive burden is another participation limiting factor. CBT depends on sustained attention, working memory, and the ability to translate session content into plans that are implemented between sessions. Qualitative findings describe depression related reductions in concentration and energy that interfere with participation and between-session practice (Hanssen et al., 2020). A further complication is that self-appraisal of cognitive performance is inaccurate for some individuals with bipolar disorder (Wels et al., 2023). Evidence describes state linked patterns of overestimation and underestimation that undermine realistic planning and calibration of task demands (Wels et al., 2023). Poorer insight is associated with greater residual symptoms, cognitive impairment, and disability with participation constraints related to cognition and insight persisting outside acute episodes (Grover et al., 2023).

Between-session homework demands introduce a distinct burden. They require effort when symptoms, motivation, and self-regulation are already strained. CBT for bipolar disorder commonly includes self-monitoring and structured tasks designed to build skills. Patients struggle to complete these tasks during depression due to low motivation and negative expectations. They also struggle during elevated states due to difficulty disengaging from reinforcing activities (ÖZDEL et al., 2021). Qualitative evidence indicates that homework volume feels excessive for some participants and triggers self-imposed pressure that reduces continuation of practice (Hanssen et al., 2020).

Insight and therapeutic alliance function as participation mechanisms. They shape collaboration, adherence, and willingness to sustain treatment (Strauss and Johnson, 2006; Grover et al., 2023). Poorer insight is associated with greater illness burden and functional impairment reducing consistency of engagement and follow-through (Grover et al., 2023). Treatment alliance is associated with clinically relevant outcomes in bipolar disorder (Strauss and Johnson, 2006) Engagement and continuity depend on the therapeutic relationship as well as symptom severity (Strauss and Johnson, 2006). In routine care, psychotherapy underuse also reflects patient reticence and practical adherence difficulties with engagement barriers occurring before homework failure becomes observable (Chiang and Miklowitz, 2023).

Comorbidity and adherence problems are prominent barriers in community settings where CBT is delivered. In routine care, these barriers commonly involve co-occurring conditions and adherence problems that reduce continuity of participation. Clinicians identify comorbid substance use disorders and adherence difficulties as barriers that interfere with psychosocial care delivery for bipolar disorder (Stein et al., 2015). Guideline summaries also emphasize the clinical importance of comorbidity and adherence constraints in bipolar disorder care (Yatham et al., 2018; Keramatian et al., 2023). Participation barriers often occur within complex clinical profiles rather than in narrowly defined trial samples (Jones et al., 2015; Docteur et al., 2018; Keramatian et al., 2023).

Social context influences participation capacity through stability and practical support. It also shapes whether patients have structured support that helps them sustain treatment routines (Veseth et al., 2017; Yatham et al., 2018; Keramatian et al., 2023). In bipolar disorder, therapists describe the social world as central to recovery stability, with instability undermining continuity and follow through, and treatment alliance is linked with social support, indicating that participation barriers are embedded in the patient's broader context rather than solely in individual motivation (Strauss and Johnson, 2006; Veseth et al., 2017).

These findings support a delivery-focused problem statement. CBT is effective in bipolar disorder (Chiang et al., 2017). However, patient-level barriers often limit initiation, retention, and between-session practice (Docteur et al., 2018; ÖZDEL et al., 2021; Chiang and Miklowitz, 2023). This reduces delivered dose and constrains real-world benefit (Docteur et al., 2018; Chiang and Miklowitz, 2023). This framing supports evaluating adjunct strategies based on whether they reduce participation burdens enough to increase engagement and between-session follow-through. Success is defined in psychotherapy terms rather than solely in symptom change (Chiang and Miklowitz, 2023).

4 Ketogenic metabolic therapy as a candidate adjunct for participation capacity in bipolar disorder

Adjunct psychotherapy trials in bipolar disorder prioritize clinical outcomes, while participation processes are less consistently characterized (Szentagotai and David, 2010; Oud et al., 2016). In systematic syntheses, study retention is commonly used as a proxy for treatment acceptability, whereas more granular indicators that clarify delivered psychotherapy dose and feasibility, including session attendance frequency, medication adherence, and patient ratings of helpfulness, are reported less often (Gaudiano et al., 2008; Miklowitz et al., 2021).

A participation-capacity model treats these measurement gaps as clinically relevant because CBT benefit depends on sufficient delivered dose and between-session practice (Docteur et al., 2018; Miklowitz et al., 2021; ÖZDEL et al., 2021). A candidate adjunct is evaluated based on whether it improves initiation (Chiang and Miklowitz, 2023), session continuity (Docteur et al., 2018; Miklowitz et al., 2021), and between-session follow-through (ÖZDEL et al., 2021), with success defined in psychotherapy terms rather than symptom change as the sole endpoint (Chiang and Miklowitz, 2023).

Figure 1 presents the paper's conceptual pathway linking dose and enactment dependent CBT benefit with patient-level barriers that can truncate delivered dose, and positioning KMT related domains of functioning as candidate targets that may increase CBT initiation, CBT continuity, and CBT enactment. Within this framework, KMT is considered a candidate adjunct only to the extent that it is associated with change in domains that overlap with participation capacity. Table 2 summarizes patient-level CBT engagement barriers and preliminary KMT findings relevant to psychotherapy participation in bipolar disorder.

This positioning keeps the adjunct question narrow and testable within guideline-consistent care. CBT is not recommended in acute mania (Yatham et al., 2018; Keramatian et al., 2023), and sufficient participation capacity is a prerequisite for collaborative CBT work and between-session practice (Yatham et al., 2018; Chiang and Miklowitz, 2023). This framing supports clinical implementation models that use psychotherapy participation endpoints to specify when an adjunct question is reached and to determine whether KMT functions as a meaningful adjunct in a given case (Miklowitz et al., 2021; Chiang and Miklowitz, 2023).

5 Clinical implementation of ketogenic metabolic therapy as an adjunct to cognitive behavioral therapy in bipolar disorder

Clinical implementation of KMT as an adjunct to CBT is most coherent when the goal is defined in psychotherapy terms. The operational objective is improved capacity to initiate CBT, sustain session continuity across an intended course, and complete between-session monitoring and skill practice, rather than symptom change as the sole indicator of success. This positioning remains bounded by guideline framing in which CBT is an adjunctive option for bipolar depression and maintenance, with no recommendation for acute mania due to insufficient evidence in that phase (Yatham et al., 2018; Chiang and Miklowitz, 2023; Keramatian et al., 2023).

A participation-focused clinical model may support a staged, sequential use of KMT relative to CBT rather than assuming concurrent delivery. Figure 2 summarizes these sequential implementation points for considering KMT as a preparatory or subsequent adjunct when patient-level barriers limit delivered CBT dose. When participation capacity is expected to be insufficient for CBT to be started and sustained, KMT can be considered first as a preparatory intervention, with CBT initiated when pre-specified participation-readiness indicators suggest that a minimally adequate CBT dose can be delivered. When participation difficulties are observed in a CBT attempt, or when there is a history of incomplete CBT courses, KMT can be considered after the difficulty is identified, with CBT re-offered when the identified participation barrier has improved sufficiently to attempt a minimally adequate CBT dose. In research protocols, these readiness indicators should be specified in advance and distinguished from the subsequent CBT participation endpoints used to evaluate initiation, session continuity, delivered dose, and between-session follow-through. Concurrent delivery of KMT and CBT may be considered, but it is not treated as the default clinical model here, although concurrent delivery of KMT at the initiation of CBT for bipolar remains a question that may be evaluated in future research. Table 3 specifies research design and reporting priorities for testing whether KMT reduces patient-level participation barriers that limit delivered CBT dose in bipolar disorder.

Validated instruments and standardized measurement approaches can be used to measure CBT participation processes and the factors that determine delivered dose, including therapeutic alliance, implementation acceptability and feasibility, and observer rated treatment integrity assessed through fidelity and competence methods (Muse and McManus, 2013; Weiner et al., 2017; Cameron et al., 2018; Goldberg et al., 2020). Standardized homework and between session adherence measures quantify enacted CBT dose by capturing practice completion and quality rather than attendance alone (Kazantzis et al., 2016). With these tools, the adjunct question can be tested at prespecified implementation points by assessing whether participation capacity supports CBT initiation, continuity, and between session follow through (Fernandez et al., 2015; Kazantzis et al., 2016; Weiner et al., 2017).

When KMT is implemented prior to CBT, the clinical question is whether patient-level participation capacity improves enough for CBT to begin and establish early continuity. Clinicians can assess this using early participation indicators that map directly onto CBT delivery, including transition from recommendation to initiation, early attendance continuity (Docteur et al., 2018), and initiation of routine between-session monitoring and practice (Docteur et al., 2018; ÖZDEL et al., 2021; Chiang and Miklowitz, 2023). Premature discontinuation can occur early in structured CBT programs, and early attendance patterns and discontinuation timing are clinically informative for judging whether an adjunct strategy increases the likelihood that an intended CBT dose will be delivered (Docteur et al., 2018; Miklowitz et al., 2021),

When patient-level participation difficulties are observed in a CBT attempt, KMT can be considered as a subsequent adjunctive intervention rather than concurrent delivery, with the clinical objective of improving participation capacity so that CBT can be re-offered and completed. In this scenario, clinician assessment is more informative when it specifies the observed participation problem, such as repeated missed sessions, early discontinuation risk, or persistent non-completion of monitoring and planned practice, and then assesses whether a later CBT course shows improved session continuity and between-session follow-through (Docteur et al., 2018; ÖZDEL et al., 2021). Qualitative evidence from bipolar psychotherapy programs requiring home practice indicates that low energy, reduced concentration, and perceived excessive task demands can undermine adherence and it supports a clinical approach that treats homework failure as a measurable participation barrier rather than assuming it reflects motivation alone (Hanssen et al., 2020; ÖZDEL et al., 2021).

Across staged implementations, clinical assessment is more informative when it tracks psychotherapy participation endpoints and the factors that shape engagement and continuity. Participation endpoints include CBT initiation status, session continuity, premature discontinuation, and completion of between-session monitoring and assignments (Docteur et al., 2018; ÖZDEL et al., 2021). Complementary clinical indicators include therapeutic alliance and perceived social support (Strauss and Johnson, 2006; Veseth et al., 2017), comorbid substance use and adherence difficulties that interfere with psychosocial care delivery (Stein et al., 2015), and insight and self-appraisal accuracy when these affect planning and task calibration (Grover et al., 2023; Wels et al., 2023).

When CBT is indicated but cannot be initiated, is discontinued before an adequate dose is delivered, or cannot be translated into between-session practice despite ongoing treatment contact, the adjunct question is whether KMT should be offered as a preparatory or subsequent intervention to reduce participation-limiting burden enough for CBT initiation, session continuity, and between-session follow-through to become feasible. This participation-capacity framing keeps inference narrow and guideline-consistent while the bipolar KMT evidence base remains preliminary (Docteur et al., 2018; Yatham et al., 2018; Miklowitz et al., 2021; Sethi and Ford, 2022; Chiang and Miklowitz, 2023; Keramatian et al., 2023; Rog et al., 2024).

6 Conclusion

CBT is an evidence-based adjunctive psychotherapy for bipolar disorder, with meta-analytic support for benefit when added to standard care (Oud et al., 2016; Chiang et al., 2017; Miklowitz et al., 2021). However, the clinical value of CBT depends on whether patients can initiate treatment, sustain session continuity, and complete between-session practice that delivers CBT's active ingredients in daily life (Docteur et al., 2018; Miklowitz et al., 2021; Chiang and Miklowitz, 2023). Patient-level participation barriers in bipolar disorder function as a clinically meaningful constraint on delivered dose and real-world benefit, particularly in routine care where psychotherapy remains underused and premature discontinuation occurs even in structured programs (Docteur et al., 2018; Chiang and Miklowitz, 2023).

Clinical implementation may be clinically appropriate when KMT is used sequentially relative to CBT, either as a preparatory intervention when participation capacity is insufficient for CBT initiation or early continuity, or as a subsequent adjunct after participation difficulties or incomplete CBT courses, with CBT re-offered when participation endpoints improve. Clinician assessment is more informative when it is anchored to observable participation outcomes and the factors that shape engagement, including alliance and social stability (Strauss and Johnson, 2006; Veseth et al., 2017), comorbid substance use and adherence difficulties (Stein et al., 2015), and insight or self-appraisal limitations when these affect planning and task calibration (Grover et al., 2023; Wels et al., 2023). Premature discontinuation can occur early in structured CBT programs, making early attendance patterns clinically informative when judging whether an adjunct strategy increases the likelihood that an intended CBT dose will be delivered (Jones et al., 2015; Docteur et al., 2018; Hautzinger and A2 BipoLife Consortium, 2024).

Given heterogeneity in bipolar disorder presentations, participation barriers, and likely response to KMT, future trials should test this participation-capacity proposition in adequately powered designs using standardized psychotherapy participation outcomes. Trials should also include careful characterization of who benefits and who does not, and qualitative analyses that clarify feasibility, burden, and discontinuation (Oud et al., 2016; Hanssen et al., 2020; Miklowitz et al., 2021). Symptom change remains an important outcome, but it is not the sole clinical rationale for CBT delivery in bipolar disorder, because CBT targets relapse prevention and functional recovery skills that remain relevant when symptoms are intermittent, residual, or already improving (Chiang et al., 2017; Yatham et al., 2018; Keramatian et al., 2023).

This conceptual analysis positions KMT as a candidate adjunct by narrowing the question to participation capacity rather than disorder-level efficacy claims. The current bipolar KMT literature remains early and does not support conclusions about comparative effectiveness, but it consistently describes change in domains that overlap with patient-level participation constraints, including mood stability, sleep, energy, anxiety, cognition, and functioning. Together, these points define a clinical conceptual framework that operationalizes KMT as a candidate adjunct using psychotherapy-defined endpoints of CBT initiation, session continuity, and between-session follow-through.

Edited by: Stefania Cella, University of Campania Luigi Vanvitelli, Italy

Reviewed by: Jenny Ann Rydberg, Consultant, Monteux, FranceSakir Yilmaz, Abdullah Gül University, Türkiye