Even a mentally deranged man can be cured by treatment of Transcendental sound

SB 1.11.3 purport …This sound of the Lord is identical with the Lord, as we have tried to explain by the nondual position of the Lord.

The material existence of our present status is full of fear. Out of the four problems of material existence, namely the food problem, the shelter problem, the fear problem and the mating problem, the fear problem gives us more trouble than the others.

We are always fearful due to our ignorance of the next problem. The whole material existence is full of problems, and thus the fear problem is always prominent. This is due to our association with the illusory energy of the Lord, known as māyā or external energy, yet all fear is vanished as soon as there is the sound of the Lord, represented by His holy name, as it was sounded by Lord Śrī Caitanya Mahāprabhu in the following sixteen  words:Hare Kṛṣṇa, Hare Kṛṣṇa, Kṛṣṇa Kṛṣṇa, Hare Hare Hare Rāma, Hare Rāma, Rāma Rāma, Hare Hare  

We can take advantage of these sounds and be free from all threatening problems of material existence. 

SB 1.18.18 purport …The mental diseases of the present generation are more acute than bodily diseases

SB 2.1.17 purport …. Oṁkāra is the seed of all transcendental sound and it is only the transcendental sound which can bring about the desired change of the mind and the senses.

Even a mentally deranged man can be cured by treatment of transcendental sound. In the Bhagavad-gītā, the praṇava (oṁkāra) has been accepted as the direct, literal representation of the Supreme Absolute Truth.

One who is not able to chant directly the holy name of the Lord, as recommended above, can easily chant the praṇava (oṁkāra).

This oṁkāra is a note of address, such as "O my Lord," just as oṁ hari om means "O my Lord, the Supreme Personality of Godhead." As we have explained before, the Lord's holy name is identical with the Lord Himself. So also is oṁkāra.

But persons who are unable to realize the transcendental personal form or name of the Lord on account of their imperfect senses (in other words, the neophytes) are trained to the practice of self-realization by this mechanical process of regulating the breathing function and simultaneously repeating the praṇava (oṁkāra) within the mind.  

SB 2.1.18 purport …The mind, although ceasing to think of sensual activities at present, remembers past sensual activities from the subconscious status and thus disturbs one from cent percent engagement in self-realization.

Therefore, Śukadeva Gosvāmī recommends the next step of assured policy, namely to fix one's mind in the service of the Personality of Godhead. Lord Śrī Kṛṣṇa, the Supreme Personality of Godhead, also recommends this direct process in the Bhagavad-gītā (6.47).

Thus, the mind being spiritually cleansed, one should at once engage himself in the transcendental loving service of the Lord by the different devotional activities of hearing, chanting, etc.

If performed under proper guidance, that is the surest path of progress, even for the disturbed mind.

Some Conclusions — If we accept the actual treatment given for mental relief by the bona fide  spiritual master, then we can be cured. If we dont accept this treatment then we can hardly expect peace of mind or progressive spiritual life.