| Title: |
The heterogeneity of Depression: Towards a better understanding of the biological basis (PhD Experiment 6: Go No / Go ERPs MDD and healthy controls: Impact of subtype and severity) |
| Research Area(s): |
Depression |
| Background: |
Rationale (Experiment 6): A better understanding of the biological basis of depression heterogeneity and severity may provide further insight into this disorder and its subtypes. The hypotheses will be dependent on subtypes observed in experiment 1. |
| Aims: |
Aim of Experiment 6: To investigate the impact of subtype and severity on response inhibition.
Research Question/s:
• Is there a difference in level of impulsivity between the subtypes identified in experiment 1?
• Does brain functioning differ by subtype and/or severity?
• How does brain functioning differ with regard to response inhibition in patients with varying levels of severity?
• Are levels of behavioural impulsivity (as measured by behavioural responses on the go/no-go task) associated with suicidality in depression?
• Are levels of neural inhibition (associated with response inhibition during the go/no-go task) associated with suicidality in depression?
• What is the impact of severity, subtype and sucidality on behavioural impulsivity?
• What is the impact of severity, subtype and suicidality on neural inhibition?
• Does sucidality impact on neural inhibition over and above severity and subtype?
Hypotheses:
• It is expected that impulsivity will be greater in patients with melancholic depression compared to patients with non-melancholic depression.
• It is expected that melancholic depressed patients (with psychomotor retardation) will exhibit slower reaction times in comparison to non-melancholic depressed patients (without psychomotor retardation) and controls respectively.
• It is expected that patients with melancholic depression will exhibit greater errors of co-mission in comparison to patients with non-melancholic depression and controls respectively.
• It is expected that patients with melancholic depression with exhibit greater peak amplitude at P200 in comparison to non-melancholic depressed patients and controls respectively.
• It is expected that patients with more severe melancholic depression will exhibit greater peak amplitude at P200 and reduced peak amplitude at P300 in comparison to patients with less severe melancholic depression and controls respectively.
• It is expected that patients with high levels of impulsivity and suicidality will exhibit greater errors of comission on the go/no-go task.
• It is expected that patients with high levels of impulsivity and suicidality will exhibit greater peak amplitude at P200 and reduced peak amplitude at P300.
• It is expected that melancholic depressed patients will exhibit higher levels of impulsivity and suicidality compared to non-melancholic depressed patients by way of greater errors of comission, greater peak amplitude at P200 and reduced peak amplitude at P300.
• It is expected that more severely depressed patients will exhibit higher levels of impulsivity and suicidality compared to less severely depressed patients by way of greater errors of comission, greater peak amplitude at P200 and reduced peak amplitude at P300.
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| Method: |
Methodology: Various ANOVAs and Regression techniques will be conducted. For example, an ANOVA will be conducted using a between-group (MDD subtype versus control) X within-subject design including, site (frontal, central, parietal) and hemisphere (left, right). Logistic or multinomial regression analyses will be conducted to predict the depression subtype as the dependent variable. The impact of anxiety comorbidity, suicidality and impulsivity will also be examined. |