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Proposal 1 Review
Previous research with adults has shown that both experiencing early life stress and possessing the short allele of the 5HHT gene are associated with an increased risk for developing depression. In addition, possessing the short allele of the 5HHT gene is also associated with heightened reactivity of the amygdala in response to negative stimuli. This proposal takes a developmental approach to this issue, investigating whether amygdala reactivity may underlie the link between the serotonin (5-HTT) reuptake inhibitor gene, early life stress, and the development of depression in children.
Understanding the how genetic predispositions and early experiences may change brain function and convey risk for mental illness is a critical area of study. I think that the background literature was clearly reviewed, the rationale and aims of this proposal are articulated well, however, I have a number of issues that the author may want to consider before submitting this proposal.
- The fact that the author was planning to study children came as a bit of a surprise when I got to the aims. Similarly, I thought the issue of attribution style was neglected in the introduction. In addition, I would have liked to see a justification for why 6-12 year old children were chosen and how potential developmental changes in brain structure and function across this age range will be accounted for in the analysis of MRI data.
- It might be interesting to include both positive and negative emotions in the imaging task. How is amygdala reactivity to positive emotional expressions? Is amygdala dysfunction specific to over reactivity in response to negative, or is there also under reactivity to positive emotions? Also does the author predict laterality differences in responses to fear vs. anger, given the literature demonstrating that anger is an approach emotion but fear is a withdrawal emotion.
- I would have liked to see more information regarding the fMRI analysis. Why is only the right amygdala activity analyzed? How is the signal change score calculated? Is it standard practice to comparing activity on different tasks (emotion vs. sensorimotor)
- The author might also like to consider variable that may need to be controlled for in the analysis. For example, rather than simply grouping children into maltreated vs. not, it may be important to consider the duration and/or severity of the trauma and how recently it occurred.
- The sample size seems extreme. At $800 per session, imaging 500 children would cost $400,000. The author may consider conducting a power analysis or looking at the developmental imaging literature to determine a realistic sample size.
Minor issues
-There are a number of places where the author could use fewer words and make her writing sound stronger by using the active voice, rather than the passive voice. E.g. pg 2 1st paragraph “this is thought to be explained by the fact that the short allele…” instead write “The short allele….”
-There were a number of spelling error, typos and grammatical errors that detracted from the clarity of the writing.