The mood disturbance is sufficiently severe to cause marked impairment in occupational functioning or in usual social activities or relationships with others, or to necessitate hospitalization to prevent harm to self or others, or there are psychotic features. A distinct period of persistently elevated, expansive, or irritable mood, lasting throughout at least 4 days, that is clearly different from the usual nondepressed mood. The episode is associated with an unequivocal change in functioning that is uncharacteristic of the person when not symptomatic. The disturbance in mood and the change in functioning are observable by others. The episode is not severe enough to cause marked impairment in social or occupational functioning, or to necessitate hospitalization, and there are no psychotic features.
Some disorders have similar or even overlapping symptoms.
The clinician, therefore, in his diagnostic attempt has to differentiate against the following disorders which need to be ruled out to establish a precise diagnosis.