Here are some great topics that should make your paper interesting:
Do anti-depressant drugs really work? Should they be so widely prescribed?
Can brain activity in infants predict later mental health issues?
Why is anxiety overtaking depression as a major mental health problem, especially among teens?
Can psychologists accurately predict someone who might become violent?
Is marijuana a better choice for some mental health issues than prescription drugs?
What are the best non-medical ways to treat mental illness?
Are mass shooters mentally ill?
How can exercise and diet affect mental health?