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Dysfunctional attitudes and 5-HT2 receptors during depression and self-harm
Jeffrey H Meyer1, Shelley McMain, Sidney H Kennedy
1Vivian M. Rakoff PET Imaging Centre, Clarke Division, Centre for Addiction and Mental Health, Department of Psychiatry, University of Toronto, 250 College St., Toronto, ON, M5T 1R8, Canada. jmeyer@camhpet.on.ca
Objective:
Dysfunctional attitudes are negatively biased assumptions and beliefs regarding oneself, the world, and the future. In healthy subjects, increasing serotonin (5-HT) agonism with a single dose of d-fenfluramine lowered dysfunctional attitudes. To investigate whether the converse, a low level of 5-HT agonism, could account for the higher levels of dysfunctional attitudes observed in patients with major depression or with self-injurious behavior, cortex 5-HT(2) receptor binding potential and dysfunctional attitudes were measured in patients with major depressive disorder, patients with a history of self-injurious behavior, and healthy comparison subjects (5-HT(2) receptor density increases during 5-HT depletion).
Method:
Twenty-nine healthy subjects were recruited to evaluate the effect of d-fenfluramine or of clonidine (control condition) on dysfunctional attitudes. Dysfunctional attitudes were assessed with the Dysfunctional Attitude Scale 1 hour before and 1 hour after drug administration. In a second experiment, dysfunctional attitudes and 5-HT(2) binding potential were measured in 22 patients with a major depressive episode secondary to major depressive disorder, 18 patients with a history of self-injurious behavior occurring outside of a depressive episode, and another 29 age-matched healthy subjects. Cortex 5-HT(2) binding potential was measured with [(18)F]setoperone positron emission tomography.
Results:
In the first experiment, dysfunctional attitudes decreased after administration of d-fenfluramine. In the second experiment, in the depressed group, dysfunctional attitudes were positively associated with cortex 5-HT(2) binding potential, especially in Brodmann's area 9 (after adjustment for age). Depressed subjects with extremely dysfunctional attitudes had higher 5-HT(2) binding potential, compared to healthy subjects, particularly in Brodmann's area 9.
Conclusions:
Low levels of 5-HT agonism in the brain cortex may explain the severely pessimistic, dysfunctional attitudes associated with major depression.