What is the difference between obsessive-compulsive disorder and doctrinal extremism, and does extremism entirely or partially prohibit intercession?

Obsessive whispering (waswas) can lead to extremism (ghuluw), which is excessive delving and burdening oneself in a matter. The Prophet, peace and blessings be upon him, forbade extremism, saying: "Beware of extremism in religion, for indeed, what destroyed those before you was extremism in religion." Shaykh al-Islam Ibn Taymiyyah explained that this warning is general and applies to all types of extremism. As for the hadith, "Two types of my Ummah will not attain my intercession: an oppressive, tyrannical leader; and every extremist apostate," it was narrated by Al-Tabarani and deemed good by Al-Albani. This hadith specifically refers to those who deviate from the religion, like the Khawarij, and not to those who suffer from obsessive-compulsive disorder (waswas); for one who is compulsively afflicted by waswas is not held accountable. Al-Bayhaqi and Al-San'ani clarified that the "mariq" (apostate) is one who departs from the religion, and the Prophet's intercession will not reach him.