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Sensitivity to cholecystokinin-tetrapeptide in major depression
Diana Koszycki1, John Copen, Jacques Bradwejn
1Department of Psychiatry, University of Ottawa, and the Stress and Anxiety Clinical Research Unit, Institute of Mental Health Research, Royal Ottawa Hospital, 1145 Carling Avenue, Ottawa, ON K1Z 7K4, Canada. dkoszyck@rohcg.on.ca
Background:
Sensitivity to the panicogenic effects of cholecystokinin-tetrapeptide (CCK-4) is enhanced in panic disorder patients relative to normal controls (NC). In the present study, we determined whether sensitivity to CCK-4 is enhanced in patients with major depressive disorder (MDD) with no history of panic attacks. We also determined whether CCK-4 would exacerbate depressive symptoms.
Methods:
The study used a double-blind, randomized, placebo-controlled design. Behavioral and cardiovascular response to a submaximal dose (20 microg) of CCK-4 was studied in seven patients with MDD and 12 NC subjects.
Results:
None of the subjects panicked with placebo, whereas 29% of MDD and 17% of NC subjects panicked with CCK-4. There was no significant difference between groups on the frequency of CCK-4-induced panic or the number and intensity of panic symptoms. No significant difference was detected for cardiovascular response to the CCK-4 challenge. CCK-4 did not worsen depressive symptoms in MDD patients.
Limitations:
Small number of study subjects.
Conclusions:
These data indicate that MDD patients show a response to CCK-4 that is comparable to NC. The lack of effect of CCK-4 on depressive symptoms suggest that central CCK receptors may not play an important role in the pathophysiology of MDD.