Abrupt changes in a person's personality can be the result of prescription drugs. Someone abusing prescription drugs can become aloof or combative and argumentative. If this is a dramatic difference in the person's personality, consider the possibility that the person is abusing prescription drugs.  On stimulants, the person may become talkative, but their conversation may be hard to follow. They may frequently change the subject, unable to stay focused on a topic for any length of time. You may notice a person seeming paranoid, overly anxious about what other people say or do. The person may seem defensive or argumentative, even if this is uncharacteristic. They may become less able to deal with stress, more quick-tempered or sullen.<re>  Irritability is a common characteristic of someone with a prescription drug problem. The person may appear less mature than before, refusing to accept blame for any situation or minimizing her part in it. Making poor decisions, a result of not being able to think through everyday problems, is a common side-effect of drug abuse. The person may be unable to think about things unrelated to the drug.  You may notice the person being more obnoxious or silly than usual.  Poor concentration and problems with memory are signs of drug abuse.

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Write a summary of the previous text in Vietnamese:
Cân nhắc sự thay đổi trong tính cách hoặc tâm trạng. Quan sát phản ứng về mặt cảm xúc. Chú ý đến sự thay đổi trong khả năng chú ý của người đó.