<p dir="ltr">Attention-Deficit/Hyperactivity Disorder (ADHD) in adults is a common condition characterized by difficulties in regulating attention, activity, and goal- directed behavior. These challenges are particularly associated with inattentive symptoms, which can lead to significant impairments in daily life. Cognitive behavioral therapy (CBT) is recommended as a psychosocial intervention for ADHD and is often delivered in a uniform format, regardless of the predominant symptomatology. However, as inattention and hyperactivity/impulsivity present distinct challenges, there is reason to believe that presentation-specific treatments could be more effective. CBT for ADHD-Inattentive Presentation (CADDI) is specifically designed to address inattention and includes skills training in organizing and initiating activity and coping with procrastination and passivity. In addition, mindfulness meditation is practiced throughout treatment. The aim of this thesis was to evaluate the feasibility, patient perspectives, and effectiveness of CADDI in routine outpatient clinics.</p><p dir="ltr">Study I investigated feasibility and preliminary effects of CADDI. Feasibility was evaluated through several measures, treatment adherence, attrition and acceptability. Method: In an open trial design, 39 adult patients with ADHD-I were included. Participants underwent 14 sessions of the CADDI protocol, at four outpatient settings. Results: The CADDI protocol proved feasible in terms of session completion and treatment acceptability. However, adherence in terms of home-assignment completion was low, and attrition was high.</p><p dir="ltr">Study II explored participants perception of treatment according to the CADDI protocol. Methods: Participants were recruited from treatment groups following the protocol of CADDI, at three psychiatric outpatient units in Stockholm, Sweden. Individual semi-structured interviews, lasting on average 44,6 minutes, were conducted with 14 adults after the completion of CADDI. Interviews explored participants' perceptions of CADDI, its usefulness, and asked for suggestions for improvement. Interviews were conducted by independent interviewers, transcribed and analyzed using reflexive thematic analysis. The analysis generated three themes: "Factors of importance for change", with the subthemes; the group, therapeutic components, structure of treatment, and motivation, "Gains in treatment", with the subthemes; insight and understanding, increased attention, and planning and acting, and "Challenges with ADHD-I and remaining needs", with the subthemes; ADHD as a lifelong condition, maintaining gains in treatment, and wish for further support.</p><p dir="ltr">Study III Investigated the effectiveness of CADDI in a multicenter superiority trial comparing the effectiveness of CADDI with regular CBT treatment for ADHD. Method: A multicenter, pragmatic, randomized controlled trial compared CADDI to Hesslinger's dialectical behavior therapy protocol. The study included 108 participants from six psychiatric outpatient clinics in Stockholm. Self-reported scales were used in assessment pre- and post-intervention. Primary outcome measure were behavioral activation and procrastination, secondary outcomes were symptoms of ADHD, depression, quality of life and functional impairment. Between and within-group effects were calculated following intention-to-treat analysis using multilevel modeling.</p><p dir="ltr">Results: Between-group analysis showed that participants in the CADDI group had significantly greater improvement on the primary outcome measure of activation at post assessment (p = . 045, d = 0.49). No significant between-group effects were found on the other outcome measures, even though within-group analyses showed larger effect sizes in the CADDI condition relative to the control condition on several measures. Even though the results indicated differences in within-group eff

<p dir="ltr">Attention-Deficit/Hyperactivity Disorder (ADHD) in adults is a common condition characterized by difficulties in regulating attention, activity, and goal- directed behavior. These challenges are particularly associated with inattentive symptoms, which can lead to significant impairments in daily life. Cognitive behavioral therapy (CBT) is recommended as a psychosocial intervention for ADHD and is often delivered in a uniform format, regardless of the predominant symptomatology. However, as inattention and hyperactivity/impulsivity present distinct challenges, there is reason to believe that presentation-specific treatments could be more effective. CBT for ADHD-Inattentive Presentation (CADDI) is specifically designed to address inattention and includes skills training in organizing and initiating activity and coping with procrastination and passivity. In addition, mindfulness meditation is practiced throughout treatment. The aim of this thesis was to evaluate the feasibility, patient perspectives, and effectiveness of CADDI in routine outpatient clinics.</p><p dir="ltr">Study I investigated feasibility and preliminary effects of CADDI. Feasibility was evaluated through several measures, treatment adherence, attrition and acceptability. Method: In an open trial design, 39 adult patients with ADHD-I were included. Participants underwent 14 sessions of the CADDI protocol, at four outpatient settings. Results: The CADDI protocol proved feasible in terms of session completion and treatment acceptability. However, adherence in terms of home-assignment completion was low, and attrition was high.</p><p dir="ltr">Study II explored participants perception of treatment according to the CADDI protocol. Methods: Participants were recruited from treatment groups following the protocol of CADDI, at three psychiatric outpatient units in Stockholm, Sweden. Individual semi-structured interviews, lasting on average 44,6 minutes, were conducted with 14 adults after the completion of CADDI. Interviews explored participants' perceptions of CADDI, its usefulness, and asked for suggestions for improvement. Interviews were conducted by independent interviewers, transcribed and analyzed using reflexive thematic analysis. The analysis generated three themes: "Factors of importance for change", with the subthemes; the group, therapeutic components, structure of treatment, and motivation, "Gains in treatment", with the subthemes; insight and understanding, increased attention, and planning and acting, and "Challenges with ADHD-I and remaining needs", with the subthemes; ADHD as a lifelong condition, maintaining gains in treatment, and wish for further support.</p><p dir="ltr">Study III Investigated the effectiveness of CADDI in a multicenter superiority trial comparing the effectiveness of CADDI with regular CBT treatment for ADHD. Method: A multicenter, pragmatic, randomized controlled trial compared CADDI to Hesslinger's dialectical behavior therapy protocol. The study included 108 participants from six psychiatric outpatient clinics in Stockholm. Self-reported scales were used in assessment pre- and post-intervention. Primary outcome measure were behavioral activation and procrastination, secondary outcomes were symptoms of ADHD, depression, quality of life and functional impairment. Between and within-group effects were calculated following intention-to-treat analysis using multilevel modeling.</p><p dir="ltr">Results: Between-group analysis showed that participants in the CADDI group had significantly greater improvement on the primary outcome measure of activation at post assessment (p = . 045, d = 0.49). No significant between-group effects were found on the other outcome measures, even though within-group analyses showed larger effect sizes in the CADDI condition relative to the control condition on several measures. Even though the results indicated differences in within-group eff