Prepositions: of vs in

Zen we need a bit more context

Hi!

Evidence of brain pathology. ("In" would work if you found evidence in the brain pathology department of a college or something, but you would need more context there, and "either" just doesn't make sense; you would need to pair it with another pronoun and noun.)

Consideration of individual differences. (Again, "in" could potentially make sense, but it would need more context.)

Presence of medical illness. (If medical illness were the shorthand for a place like a department, "in" would make sense, I guess.)

Symptoms of arthritis.

On the last one, you could get away with either. "Of" would imply one was doing therapy, "in" would imply one was in the field of therapy (a therapist, etc.).

Overall, "in" is mostly used to describe the location of something or someone, "of" would, I guess, in a way, refine the noun. (Symptoms. Of what? Arthritis.) And "either" should, for the most part, be followed by two or more nouns, one of which is correct or the result, but which is unknown to the speaker.

Hope I helped!