How do physical conditions such as hypo and hyper thyroidism contribute to substance dependence?

No, addictive personality does, but medical conditions such as this do not.

Now, there are some medical conditions that would. Say someone has to take pain meds after an accident. They can then get addicted to pain meds.

The situations vary. I wonder what substance you are talking about. Is it a prescribed med? If it is a street drug I would have to say no.