Prior to 2000, they took you at your word.
Now you sign the HIPPA release during your BI and they search a database of info. That database is held by a third party who collects info from insurance companies and shares the infor with law enforcement and insurance company fraud units. So they can see some stuff. They also have access to any narcotic perscriptions you got and from there can back track to doctors who treated you and the like.
Just be advised that if you don't list something....and they find out later on you did have, you get fired. I know of a cop (eight years on) who had a broken arm as a kid and it was set with pins. Thirty years later he fell and broke his wrist fighting a perp. He went to the ER, they e-rayed it, cast, went home. Job paid him to sit home for a week and he had to see teh NYPD doc to get back to work on modified duty. Doc reviewed x-rays from hospital and saw pins in arm and previous fracture and no listing in medical file. Cop ended up being told: get fired or resign for lying during application. He got a lawyer and PBA got involved. He ended up leaving the NYPD.
What are you so worried about? Maybe we can help before you make an ant hill a mountain.
-In God we trust. All others, put your hands on the car and don't move.