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The Biological Mechanisms of depression in adolecence, Second Main…

- - - - It is important to study adolescence depression to minimise the harmful outcomes
      - as many as 84% of depressed youths will relapse and these individuals are at particularly high risk for developing a wide range of psych-atric and physical health problems in later adulthood - Guerry & Paul, 2011
- - - - Stress is a risk factor for depression
        
        An increase of HPA axis activity appears to be a major causal factor in depression
        
        Depression is associated with the enlargement of the adrenal gland and elevated levels of cortisol in the blood: triggered by the drive from CRF – containing neurons at the start of the HPA axis is increased
        
        Increased drive might arise from the increased activity of noradrenwegic neurons of the locus coeruleus that is observed in depression
        An important factor in depression is the weakened negative feedback of corticosteroids in the brain
  - - - There is considerable evidence for structural brain alterations in cortico-limbic and striatal regions in adult depression, with meta-analyses reporting reductions in the volumes of the amygdala and hippocampus, of striatal regions including the caudate and putamen, and of pre-frontal regions including the orbito frontal cortex, anterior cingulate cortex, and dorsolateral prefrontal cortex. Similar alterations are found in adolescence but with smaller evidence - whittle
        
        Adolescense with depression tend to have smaller hippocampuses and amygdala volumes than those without depression - whittle et al
        
        adolescence reported thinner cortices in the right latera land left medial prefrontal regions, although some other regions showed increased thickness - whittle
- - - - Colich, N. L., Kircanski, K., Foland-Ross, L. C., & Gotlib, I. H. (2015). HPA-axis reactivity interacts with stage of pubertal development to predict the onset of depression. Psychoneuroendocrinology, 55, 94-101.
  - - - Andersen, S. L., & Teicher, M. H. (2008). Stress, sensitive periods and maturational events in adolescent depression. Trends in neurosciences, 31(4), 183-191.
- - - - Therefore this could be linked to how the environment and biological could both have an impact on depression in adolescents because the environment causes biological changes
      - Gunnar and colleagues(2009),using a performance stressor (Trier Social StressTest), found significant changes in HPA reactivity around the transition to adolescence, and further showed that pubertal stage correlated with increased HPA activity. In contrast to Stroud and colleagues (2009), (Dahl & Gunnar, 2009).
  - - - Through Colich et al., (2015) it was found that increase in doressive symptoms are predicted by blunted corticol reactivity in younger girls but elevated cortisol reactivity in older girls
        
        utility of cortisol response to stress and pubertal development
- - - - Adolescence have a combination of an enhanced bottom - up emotional processing in subcortical regions and less effective top down regulation from prefrontal regions might lead to an imbalance between emotion processing and control systems during adolescence. This imbalence might play a role in the increased risk for affective disordorse during this period - (Hare et al., 2008).
        
        Adolescence deal with dramatic changes in their social environment and interactions that might serve as a stressor driving activity in hypersensitive affective systems that immature prefrontal control circuitry cannot effectively regulate. This shows a combination of biological susceptibility and environmental context might underlie the prevalence of affective disorder onset during adolescence
  - - - relations between depressive symptoms and the developmental trajectory of cortical thickness in the parietal lobe and surface area in several regions,
        
        the results were specific for cortical development, as we did not find any relationships between depressive symptoms and development of hippocampus or amygdala volume.
        
        the amygdala are thought to be important forregulating emotional arousal which is related to depressive symptomatology,
  - - - depression followed bouts of insomnia, suggesting that sleep disturbance might serve, in some instances, as a mediating link