It's not clear what you mean by "residential treatment center" and "schooling".
Residential treatment facility cost s usually deductible as medical expenses, which is subject to itemizing deductions and the 7.5% of income (AGI) threshold. You can deduct those expenses, on your tax return, if your son is your actual dependent or "medical dependent"**.
You may deduct the expenses in the year you paid the facility, not in the year(s) you paid back the loans.
**Medical dependent . If your close relative cannot be your dependent because he had more than $4,200 of gross income, but otherwise would have qualified as your dependent (basically that you & other family members provided more than half his support), then you can include in your deductible medical expenses any qualifying medical expenses you paid on his behalf just as if he was your dependent.
