The story of space travelers who lose their minds as they journey beyond Earth

Story about astronauts losing consciousness when they are farther away from Earth

I’m trying remember a short sci-fi story I read about a spacecraft attempting to travel further from Earth than ever before. The crew begins to exhibit unexplained neurological and psychological symptoms as they get further away. They become increasingly catatonic, and must be treated in the infirmary while the crew tries to find out the cause.

As the protagonist begins to lose consciousness, he or she comes up with an idea: Human consciousness isn’t just a personal phenomenon. It is dependent, in some way, on the collective impact of all other human minds. As the ship leaves Earth’s sphere of influence, its passengers begin to lose consciousness and intelligence. After realizing this, the protagonist barely manages to program the autopilot in order to turn around. The narration then describes the descent into madness and return to consciousness.

The title could have included a reference to something like \”closeness\”, ‘distance’, \”solitude\”, or \”togetherness\”. The theme and style of the story reminded me vaguely of David Brin, but after looking through his bibliography I’m not sure it was one of his works.