The Effects of ECT and/or iTBS on Olfaction and Cognition in Patients With Depression
Condition: Depression
MeSH terms: Depression; Depressive Disorder
Study type: Observational

Summary: 
      The sense of smell and cognition are known to be closely associated with mood and emotional
      processes. However, despite the clear links between olfaction and cognitive processes with
      emotional states, research into the role of olfaction, cognition, and mood disorders has so
      far yielded variable results. This study proposes to investigate the ability to detect and
      identify odours and assess cognition in a group of patients with unipolar and bipolar
      depression prior to and after receiving their scheduled electroconvulsive therapy (ECT) or
      intermittent theta burst stimulation (iTBS) treatments. Olfaction will be evaluated utilizing
      standard olfactory testing protocols using commercially available kits. Cognition will be
      evaluated utilizing standard cognitive test protocols in a functional magnetic resonance
      imaging protocol. The results will potentially shed light on the link between olfaction,
      cognition and mood disorders.
    

Detailed description: 
      The research to date indicates that olfactory sensitivity and cognition are reduced in
      depressed patients. The data also suggest that higher order cognitive odour evaluation,
      measured via identification testing, is not altered in depression. Furthermore, research into
      the effect (if any) of treatment on olfactory performance (sensitivity and identification)
      has been sparse. Researchers have called for studies that examine olfactory sensitivity prior
      to psychiatric treatment and post-remission. To the best of our knowledge there has yet to be
      a study on the effect of electroconvulsive therapy (ECT) or intermittent theta burst
      stimulation (iTBS) treatments on the olfactory performance of patients with treatment
      refractory Major Depressive Disorder (MDD) and bipolar depression. ECT has been identified as
      today's most effective treatment for severe depression due to the remission rates, speed of
      response, and the completeness of remission. iTBS is a new remittent transcranial magnetic
      stimulation (rTMS) protocol that has gained more notoriety within the field for the speed of
      administration, effectiveness of the treatment, and speed of response. Unlike rTMS, TBS
      mimics the endogenous theta rhythms of the brain, which results in greater potency in
      inducing long-term potentiation of synaptic connections in the targeted brain regions. iTBS
      has been shown to be effective in treating mood disturbances, and increasing plasticity and
      inducing neurogenesis in patients. People with MDD often struggle with cognitive impairments
      such as decreased executive functioning, attention, concentration, speed of processing, and
      working memory. The brain areas associated with cognition, such as the prefrontal cortex and
      hippocampus are negatively affected by depression; studies have shown decreased volume,
      activity, and disturbed brain connectivity in those two areas. Currently, there is a lack of
      treatment options for improving cognition in depressed patients. The investigators are
      focussing on exploring the therapeutic potential of iTBS on cognition.The preliminary
      evidence from our study will add to scientists' understanding of the short and long term
      effects of iTBS treatment on the cognitive related areas in the brain through the use of
      fMRI. The investigators also hope our research will allow psychiatrists to deliver better
      care to patients with debilitating cognitive impairments associated with depression. Overall,
      a study examining the olfactory and cognitive performance of patients with treatment
      resistant MDD and bipolar depression, pre-ECT/iTBS, post-ECT/iTBS, and post-remission would
      yield valuable insight into the link between olfaction and mood disorders as well as
      cognition and mood disorders.
    

Intervention name(s): Cognitive Function Imaging and Battery; Sniffin Sticks; Cognitive Batteries
Intervention type(s): Device; Device; Other
Intervention description(s): Individuals will be placed in the fMRI scanner and complete the NBACK Cognitive Task; Using Sniffin Sticks, olfactory functioning will be assessed using three tests: identification, discrimination, and threshold.; Participants will conduct the following cognitive batteries: DSST, TMT A & B, RAVLT
Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        The study population will consist of patients receiving iTBS or ECT at Providence
        Continuing Care Mental Health Services Site and healthy controls recruited from the
        Kingston Area. Patients may originate from a number of locations and clinics in the area
        but receive their treatment at Providence Care and have been referred to this location for
        such. Controls should be age and gender matched to participants and will be recruited from
        the Kingston region.
      
Keywords: Olfactory Dysfunction; Electroconvulsive Therapy; Theta Burst Stimulation