In Present tenses^x, Direct speech^x

>>Here is another sentence that I can't understand why present tense is used; "The doctor suggested that I decrease the amount of medication." Why "decrease" is used here? According to your explanation, I think "decreased" should be used. Could you please help me with this one? Actually,...

Thank you for helping me Tense is not so important in my mother tongue, so it's hard for me to understand the concept. I have been studying to build up my vocabulary, and I found a couple of indirect speech sentences in my text book. That one was one of them. Here is another sentence that I...