Final answer:
The next best step for the 22-year-old patient with mood-related symptoms possibly related to her menstrual cycle is to ascertain the timing of her symptoms each month. This will help determine if her symptoms correspond with premenstrual syndrome or premenstrual dysphoric disorder before considering further interventions.
Step-by-step explanation:
The 22-year-old patient who reports tension, depressed mood, and decreased productivity towards the end of each cycle might be experiencing symptoms related to her menstrual cycle. Considering her otherwise healthy profile and lack of significant medical history, the next best step in the management of this patient would be to ascertain the timing of her symptoms each month (Option 4). This step is crucial to determine if her symptoms are consistent with premenstrual syndrome (PMS) or premenstrual dysphoric disorder (PMDD), which requires a pattern that corresponds with the luteal phase of the menstrual cycle.
Direct reassurance (Option 1) without further investigation might be premature, anti-depressant therapy (Option 2) and initiating psychotherapy (Option 5) are significant interventions that should be considered after a proper assessment and diagnosis, and a psychiatry consult (Option 3) might be required if symptoms are severe and meet criteria for PMDD or another psychiatric condition.