Is it true what some claim, that the Prophet (peace be upon him) suffered from psychological problems and was not of sound mind, and how can these claims be refuted?

The answer to those who claim that Islam resulted from the genius of Muhammad, peace be upon him, must be discussed rationally, because this claim can only come from non-Muslims. We respond to them by saying that this assertion stems from malice and envy towards Islam due to its manifest blessings and widespread dissemination, and that those who make this claim do not provide evidence or proof for it. If a person were to convince billions of people of an idea, the rational would consider him a genius. So how about our Prophet Muhammad, peace be upon him, to whom both Arabs and non-Arabs submitted, whose religion spread everywhere, and whose message remained brilliant? Many enemies of Islam themselves have testified to the merits of Islam and the Prophet. A Muslim should not pay attention to these malicious individuals, for Islam is not affected by their rumors.