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The major determinant of the symptoms may have been dopamine / serotonin imbalance in the central nervous system .
 Chemical: dopamine; Chemical: serotonin
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 Chemical: dopamine; Chemical: serotonin