Brain Effects of Escitalopram and Citalopram Using fMRI

A Comparison of the CNS Effects of Equivalent Doses of Escitalopram and Racemic Citalopram Using BOLD fMRI

Escitalopram (Lexapro) and citalopram (Celexa) are similar selective serotonin reuptake inhibitors that alter blood flow to the amygdala and other brain structures involved in regulating mood. Escitalopram consists of S-citalopram while citalopram contains both S-citalopram and R-citalopram (racemic citalopram). There is evidence that R-citalopram may block the effects of S-citalopram. The hypothesis being tested is that because of the antagonist effect of R-citalopram, S-citalopram will have a greater effect on the mood circuit than racemic citalopram when equal doses of S-citalopram are administered. The study design consists of a two week medication period followed by blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) while viewing affective visual stimuli.

Inclusion Criteria:

• Healthy male aged 21 to 50 years.
• Capable of providing informed consent.
• Has an established residence and phone.

Exclusion Criteria:

• Meets DSM-IV criteria for an Axis I or II disorder.
• History of substance dependence or abuse within the past month.
• Use of NSAID's, beta blockers, calcium channel blockers, antidepressants, antipsychotic medications, lithium or other medication which in the opinion of the investigator would alter vascular responsivity.
• Regular use of sedative hypnotic or narcotic medication, or other medication that might affect the individual's perception of visual stimuli.
• History of cataracts or significant visual impairment.
• A medical condition, which in the opinion of the investigator is likely to affect the individual's perception of the visual stimuli or vascular response.
• Participation in a research protocol that included administration of medication within the past 3 months.
• Cigarette smoking.