In some cases, it could be a new and powerful enemy. This enemy might have the ability to manipulate chakra in a way that affects Naruto's mind. For example, they could send out waves of negative chakra that slowly erode Naruto's mental state. Over time, these attacks make Naruto go insane as he struggles to fight against this unseen and insidious force.
The horror in 'The Shining' is more than just Jack's novel. It encompasses a range of creepy elements such as the hotel's history, the isolation, and the unseen forces that affect everyone in the story.
Jack meets his end in a rather chaotic and terrifying way. He gets lost in the haunted hotel's madness and is ultimately overcome by supernatural forces.
Madara Uchiha could also be a likely cause. If he somehow managed to return or had a long - planned scheme that involved breaking Naruto's sanity. He was a very powerful and devious foe who could use his knowledge of the ninja world and its powers to target Naruto's mental stability.
You need to focus on showing his gradual descent into madness through his thoughts, actions, and interactions. Build up the tension and show the triggers that push him over the edge.
One consequence is the emotional trauma for his family. His wife Wendy becomes extremely fearful and has to constantly be on guard. His son Danny is also deeply affected, living in a state of constant fear. Another consequence is the breakdown of the family unit as trust and safety are completely shattered.
In the novel, Jack starts to have psychological breakdowns which lead to his violent behavior towards his family. He becomes increasingly aggressive and verbally abusive, often shouting at his wife and son. His actions are a result of the malevolent influence of the Overlook Hotel.
Another is the discovery of a dark secret about his family or the village. Maybe he finds out that the village leaders had some malicious intentions towards his family all along. This realization could be too much for him to handle and make him lose his sanity.
Iruka would be a likely candidate. He was Naruto's first teacher and has always cared about him. He would probably notice the signs early on and try his best to bring Naruto back from the brink of insanity. He might use his kind words and the bond they share to reach Naruto.