Adapted Group Therapy Compared With Usual Care for Anxiety and Depression in Adults With an Autism Diagnosis

The goal of this clinical trial is to learn whether an adapted group therapy works to treat anxiety and depression in adults with an autism diagnosis. The therapy is a form of cognitive behavioral therapy (CBT). CBT is a talking therapy. It helps people work with their thoughts, feelings, and habits. This version is adapted for adults with an autism diagnosis. The room is quiet and calm. Each session follows the same plan. The group uses a workbook. The clinic already offers this therapy. No one has yet tested how well it works compared to usual care. The main questions it aims to answer are: * Does the group therapy help participants feel better overall after 12 weeks? * Does it lower symptoms of anxiety and low mood more than usual care? * Do participants still feel better 3 months after the therapy ends? Researchers will compare the adapted group therapy with usual care. Usual care is the one-to-one follow-up that participants already get at the clinic. A computer places each participant in one of the two groups at random. This means chance decides, not the researchers and not the participant. Adults can take part if they: * Are 18 years or older * Have an autism diagnosis * Have anxiety or low mood * Already get care at the clinic Participants will: * Keep their own therapist and their usual care for the whole study * Start the group therapy now, or stay with usual care and get the same group offer later, about 6 to 7 months after the start * Meet in a group of 6 to 10 people for 1 hour a week for 12 weeks, if they start the group therapy now * Answer questionnaires on a phone or computer at the start, each week for 12 weeks, and again after 3 and 6 months * Choose whether to wear a heart rate band during group sessions. This is optional. Participants can take it off at any time. The study takes place at one outpatient clinic in Oslo, Norway.