Background: Cognitive behavioural therapy (CBT) is the most researched psychological therapy for anxiety disorders in adults, and known to be effective in this population. However, it remains unclear whether these results apply to older adults, as most studies include participants between 18 and 55 years of age. This systematic review aims to provide a comprehensive and up-to-date synthesis of the available evidence on CBT and third wave approaches for older adults with anxiety and related disorders., Objectives: To assess the effects of Cognitive Behavioural Therapy (CT, BT, CBT and third-wave CBT interventions) on severity of anxiety symptoms compared with minimal management (not providing therapy) for anxiety and related disorders in older adults, aged 55 years or over. To assess the effects of CBT and related therapies on severity of anxiety symptoms compared with other psychological therapies for anxiety and related disorders in older adults, aged 55 years or over., Search Methods: We searched the Cochrane Common Mental Disorders Controlled studies Register (CCMDCTR), CENTRAL, Ovid MEDLINE, Ovid Embase and Ovid PsycINFO to 21 July 2022. These searches were updated on 2 February 2024. We also searched the international studies registries, including Clinicalstudies.gov and the WHO International Clinical Trials Registry Platform (ICTRP), to identify additional ongoing and unpublished studies. These sources were manually searched for studies up to 12 February 2024., Selection Criteria: We included randomised controlled trials (RCTs) in older adults (≥ 55 years) with an anxiety disorder, or a related disorder, including obsessive compulsive disorder (OCD), acute stress disorder and post-traumatic stress disorder (PTSD), that compared CBT to either minimal management or an active (non-CBT) psychological therapy. Eligible studies had to have an anxiety-related outcome., Data Collection and Analysis: Several authors independently screened all titles identified by the searches. All full texts were screened for eligibility according to our prespecified selection criteria. Data were extracted and the risk of bias was assessed using the Cochrane tool for RCTs. The certainty of evidence was evaluated using GRADE. Meta-analyses were performed for outcomes with quantitative data from more than one study., Main Results: We included 21 RCTs on 1234 older people allocated to either CBT or control conditions. Ten studies focused on generalised anxiety disorder; others mostly included a mix of clinical diagnoses. Nineteen studies focused on the comparison between CBT and minimal management. Key issues relating to risk of bias were lack of blinding of participants and personnel, and participants dropping out of studies, potentially due to treatment preference and allocation. CBT may result in a small-to-moderate reduction of anxiety post-treatment (SMD -0.51, 95% CI -0.66 to -0.36, low-certainty evidence). However, compared to this benefit with CBT immediately after treatment, at three to six months post-treatment, there was little to no difference between CBT and minimal management (SMD -0.29, 95% CI -0.59 to 0.01, low-certainty evidence). CBT may have little or no effect on clinical recovery/ improvement post-treatment compared to minimal management, but the evidence is very uncertain (RR 1.56, 95% CI 1.20 to 2.03, very low-certainty evidence). Results indicate that five people would need to receive treatment for one additional person to benefit (NNTB = 5). Compared to minimal management, CBT may result in a reduction of comorbid depression symptoms post-treatment (SMD -0.57, 95% CI -0.74 to -0.40, low-certainty evidence). There was no difference in dropout rates post-treatment, although the certainty of the evidence was low (RR 1.19, 95% CI 0.80 to 1.78). Two studies reported adverse events, both of which related to medication in the control groups (very low-certainty evidence, no quantitative estimate). Only two studies compared CBT to other psychological therapies, both of which only included participants with post-traumatic stress disorder. Low-certainty evidence showed no difference in anxiety severity post-treatment and at four to six months post-treatment, symptoms of depression post-treatment, and dropout rates post-treatment. Other outcomes and time points are reported in the results section of the manuscript., Authors' Conclusions: CBT may be more effective than minimal management in reducing anxiety and symptoms of worry and depression post-treatment in older adults with anxiety disorders. The evidence is less certain longer-term and for other outcomes including clinical recovery/improvement. There is not enough evidence to determine whether CBT is more effective than alternative psychological therapies for anxiety in older adults., (Copyright © 2024 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.)