Today, scientists have found that some types of schizophrenia, which include hearing voices or having visions, may be caused by low copper levels in the body. Please get the person a full check on metal content in their system. One man commenting under the youtube video below says that he managed to cure his brother's schizophrenia:
For deflecting others' negativity which may affect the mental state of someone, it is good to recite 10:81-2; 79:28 and 7:118-22. This is from Tibb A'imma, pps 149-150.
1. Quran itself is a cure from every illness (Cure and Mercy for the believers)(Al-Israa: 82).
Reciting Quran is a very useful way to healing especially when you try to understand what you recite and keep your heart with its meanings like a person who is listening to Allah (SWT).
Reciting Quran with clear voice when ever you can with out disturbing others, might be more helpful as your heart and ears and eyes and mind join the great taste of listening to the Word f Allah.
You can recite any Chapter or Verse from Quran but there is great benefits mentioned from reciting Ayatul Kursi (Sura Al-Baqara: 255), Sura Al-Hamd, Sura Al-Tawhed, Sura Al-Qadr, Sura Yaseen, Sura Tabaarak, Sura Al- Inshiraah and other Suras.
You can recite the Sura or Verse that your heart feels more effected by it in your specific situation.
2. Remembering Allah ذكر الله is very useful in getting peace of mind as Allah says (Surely, by remembering Allah, hearts get peace and comfort) ألا بذكر الله تطمئن القلوب ((13:28).
Repeating glorifying Allah, Subhaanallah, Thenking Allah, Alhamdulillah, seeking forgiveness, Astaghfirullah and other forms of remembering Allah is very useful.
3. The best recitation iS salutations on the Prophet and his Holy Progeny (ALLAHUMMA SALLI ALA MUHAMMAD WA AALI MUHAMMAD). We have authentic Hadeeths that reciting Salawaat grants the heart peace and tranquility and elevates our spirituality and makes us get the blessings from Allah and the supplications of the angles.