Jennifer, severe depression requires more than time in a lot of cases, and intelligence doesn't make it easier to recover from depression.
In fact, the more intelligent a person is, the greater the likelihood that they will suffer from clinical depression.
Severe clinical depression requires, at the very least, counseling with a counselor trained in modern therapeutic techniques, and in many cases, one or more medications.
In addition, a healthy, clean diet, sufficient sleep with the hours being the same EVERY day (sleep hygiene), and regular exercise, are all great helps in managing severe depression.