How is dysthymic disorder different from normal sadness or unhappiness?
Any sort of normal life loss, or transition, or stress may be accompanied by a few weeks of low mood. This is what psychiatrists call an “adjustment reaction with depressed mood.” Generally things improve after a few weeks to months.
In contrast, the person with DD remains depressed for years, even decades. This is not “normal sadness or unhappiness”—it is an illness!