Should someone who is depressed take amphetamine?

Not on your own. Someone who's depressed needs to consult a primary care or psychiatric physician for full evaluation, before using any medication. You don't want to miss other medical conditions that could contribute to depression, and amphetamine is not a safe self-treatment. Some psychiatrists may use Ritalin (methylphenidate) off-label, to augment antidepressant effect in people with treatment-resistant depression, though.