根据症状首先考虑最可能的常见病和和多发病，而不是少见病、疑难病。

对于老年患者并且是首发，首先考虑脑器质性疾病、躯体疾病所致精神障碍，其次考虑心境障碍，最后考虑精神分裂症。

对于中年患者则是首先考虑心境障碍，其次才考虑脑器质性精神障碍、躯体疾病所致精神障碍和精神分裂症。

对于青少年首先考虑精神分裂症，其次才考虑心境障碍和脑器质性精神障碍、躯体疾病所致精神障碍。

According to the symptoms, the most likely common and frequently occurring diseases should be considered first, rather than rare and difficult diseases.
For elderly patients who are the first, we should first consider mental disorders caused by brain organic diseases and physical diseases, then consider mood disorders, and finally consider schizophrenia.
For middle-aged patients, mood disorders are considered first, followed by brain organic mental disorders, mental disorders caused by physical diseases and schizophrenia.
For adolescents, schizophrenia should be considered first, followed by mood disorders, brain organic mental disorders and mental disorders caused by physical diseases.