Study of the Effects of an Antidepressant Medication and Placebo on the Brain Functioning of Normal Subjects
Condition: Depression
MeSH terms: Depression
Study type: Interventional
Phase: Phase 4

Summary: 
      This study examines the effects of an antidepressant medication and placebo on the brain
      functioning of normal subjects. In this study, recordings of brain electrical activity are
      being used to detect and monitor the response to treatment with venlafaxine IR (Effexor), a
      drug used for the treatment of depression. The intent of this study is to test specific
      hypotheses regarding:

        1. long-term brain effects of a single course of antidepressant treatment

        2. pharmaco-conditioning effects underlying antidepressant tolerance/sensitization

        3. brain functional response to initial versus subsequent antidepressant trials in normal
           healthy subjects.
    

Detailed description: 
      Major Depressive Disorder (MDD) is a lifelong and recurrent illness, such that many
      individuals require multiple courses of antidepressant medication treatment. While some
      patients respond completely to each course of treatment, many do not, and with each
      unsuccessful antidepressant trial the likelihood that a patient will respond decreases. This
      raises the possibility that neurophysiologic response in subsequent antidepressant treatment
      may be influenced by learning processes including sensitization, habituation, and/or
      classical conditioning. Classical conditioning would entail the association of cues such as
      pill-taking (conditioned stimuli; CS) with the effects of active medication (unconditioned
      stimulus; US), such that later presentation of the CS alone would come to elicit a
      conditioned response (CR). Such effects could be revealed by blinded administration of
      placebo following a period of treatment with active medication. Habituation effects
      (tolerance), or sensitization effects (increased response), which require only repeated
      exposure to a stimulus, might be evidenced after repeated courses of antidepressant
      treatment. Knowledge of how learning processes impact neurophysiologic response to successive
      courses of antidepressant treatment would have relevance for clinical populations. Specific
      hypotheses, however, may be tested in healthy non-clinical samples to avoid potential
      confounding factors related to severity or chronicity of illness. Learning theories would
      suggest two hypotheses: (1) neurophysiologic response to placebo will differ between subjects
      who were previously treated with antidepressant treatment as compared to placebo (classical
      conditioning hypothesis); and (2) neurophysiologic response to an initial course of
      antidepressant treatment will differ from response to a repeated course of antidepressant
      treatment.
    

Intervention name(s): venlafaxine
Intervention type(s): Drug
Intervention description(s): venlafaxine IR 150mg
Other intervention name(s): Effexor
Intervention MeSH terms: Venlafaxine Hydrochloride
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Subjects are assigned to one of two groups (antidepressant-experienced and antidepressant-naive) and receive parallel treatment (1 week of placebo followed by 4 weeks of venlafaxine) for the duration of the study. Subjects and assessors were blinded to treatment condition.
Masking: Triple (Participant, Care Provider, Outcomes Assessor)
Primary purpose: Other