There are no real statistics as to how many applications are made for a divorce in Thailand based on insanity. Insanity is defined by Thai law and by those acts governing divorce in Thailand. You would require expert legal assistance when using such far reaching grounds for divorce in Thailand. Insanity does not only affect your divorce in Thailand but also the rights and privileges of the person being said to be insane. 

[See: Divorce in Thailand: Reasons]

In terms of Section 1516 which defines the grounds for divorce, Point 7 covers the aspect of applying for a divorce in Thailand based on one spouse being insane for 3 continuous years and who is incurable. 

Section 1519: Divorce in Thailand: Insanity   

              
This section stipulates that if an insane persons condition gives rise to grounds for a divorce in Thailand based on insanity, the person who is entitled to raise this as the reason for his/her divorce in Thailand also has to apply to court to declare the person incapacitated under Section 28 which thereby places the person in question under guardianship.

If the spouse who is insane has not as yet been declared insane by the courts, the applicant in the divorce matter shall apply not only for a divorce and liquidation of the assets but also for and order of the court to have the person declared insane. Two applications hence are filled.

It stands to reason that the courts cannot accept the reason for a divorce in Thailand based on insanity without a competent court already having declared the said person insane. If the person has not been declared insane as yet, the application for the divorce has to be accompanied by an application for the declaration of insanity. Hence Jack wants his divorce in Thailand based on Lek’s insane condition. As Lek has not been declared insane, Jack would file not only for his divorce in Thailand but also in the same court, Jack would apply for an order declaring Lek insane.

• Should the courts however find that Lek is competent and not insane; the application to have her declared insane would thereby be dismissed. As there are no grounds for divorce based on insanity, they may also dismiss the application for the divorce in Thailand. 

• Should the court however decide that Lek is insane, yet no guardian has been appointed they will grant her a living allowance and dismiss the application for a divorce. [See: Divorce in Thailand :  Maintenance & Insanity]

In the event however that a guardian is appointed during the court process in terms of Section 1463, the court will grant the divorce. Hence a divorce in Thailand will not be granted on the bases of insanity without the appointment of a guardian.