As a doctor, I can tell you that there are two main classes of antidepressants used to treat depression and anxiety. Selective serotonin reuptake inhibitors (SSRIs) work by affecting serotonin levels in the brain, which can help improve mood and reduce anxiety. Atypical antidepressants also affect serotonin levels, but they also affect other neurotransmitters such as dopamine and norepinephrine. Atypical antidepressants can be used to treat depression and anxiety, but they can also be used to help with other conditions such as smoking cessation, chronic pain, and insomnia. If you have any further questions, please do not hesitate to ask.