The article "DSM-IV handbook of differential diagnosis" discusses different mental health conditions and how they can be identified based on specific symptoms. It covers a wide range of issues such as poor school performance, anxiety, substance abuse, and personality disorders. The researchers provide a step-by-step guide to help professionals in the field make accurate diagnoses. Key findings include the importance of recognizing various symptoms like mood changes, behavioral problems, and cognitive impairments to differentiate between different mental health disorders.