Depressed patients with (a) mood reactivity alone (MR group), (b) mood
reactivity plus one or more associated features (atypical depression,
AD group), and (c) patients with neither mood reactivity nor atypical
depression (non-MR/AD group) were compared on their cortisol response
to 75 mg of desipramine (DMI), a relatively selective norepinephrine
reuptake inhibitor. AD patients exhibited a significantly higher corti
sol response to DMI compared with MR and non-MR/AD patients, suggestin
g that atypical depression may be associated with a less impaired nore
pinephrine system. MR and non-MR/AD patients did not differ, suggestin
g that mood reactivity alone is not associated with the biological pro
file observed in atypical depression. Results indicate that while mood
reactivity may be necessary for the diagnosis of atypical depression,
the additional presence of at least one associated symptom is require
d for a distinct biological profile. Our findings provide further biol
ogical validation of the concept of atypical depression.