There are certain classifications in the Diagnostic Statistical Manual of Mental Disorders (DSM-IV) that consider 'age at onset’ a relevant factor for certain interventions. However, age is rarely the sole determinant.
First, the doctor will need to gain information about your background, physical health, family, social life and other areas where your level of functioning and interactions with others is clearer. Most clinicians will naturally evaluate age appropriate behavior(s).
Psychiatrists and psychologists by definition are trained to find pathology, if any. A psychologist is more apt to evaluate your behavior and circumstances to help you develop the 'tools' to deal/handle certain behaviors or circumstances
If this type of treatment is somehow lacking, a psychiatrist and medical intervention is often the next step. This is not to say that one doctor does one or the other; in fact, both typically recognize and appreciate the role/need of each other.
**More important is that you take part in evaluating possible meds your doctor may suggest. This participation is indicative of a responsible adult:
1) What are the common side effects of this medication?
(Weight gain/loss, loss of libido, (in) decrease in appetite, fatigue, overall physical well-being, anxiety, etc.)
2) The length of time it takes to be regulated on the med.
3) Interactions with other meds or supplements you may take
4) What happens if you skip/miss a dose
5) Who/how to contact for questions
6) Do most insurance carriers cover the service and med? (Usually your job to know this one)
Forget age.
It's your doctor's job to ascertain your needs.
It's your job to question your doctor's decisions and the impact they will have on you now and in the future.