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Depression: All in Your Head?
Conference presentation

Depression: All in Your Head?

Rachael Sharman
2011 University Research Conference Program Book, p.17
USC Research Conference, 2011 (Sunshine Coast, Australia, 18-Jul-2011–22-Jul-2011)
University of the Sunshine Coast
2011
url
http://www.usc.edu.au/View
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Abstract

Psychology depression
Depression is one of the most common and debilitating mental health illnesses, with lifetime prevalence up to 20 percent. Debate continues as to whether the aetiology of depression is largely psychosocial or organic, with the theory of neurotransmitter imbalance (especially serotonin) used as the rationale for the prescription of anti-depressant medications. As a pilot investigation for a current collaborative study between USC and the Royal Children's Hospital (Brisbane); we examined depressive symptoms in 13 adolescents with a genetic disorder (phenylketonuria; PKU) that disrupts their neurotransmitter environment. Disruption to neurotransmitter function can be measured indirectly via substrate defi cit in PKU (i.e. high blood levels of phenylalanine = lowered serotonin; whereas low levels of tyrosine = lowered dopamine). Previous research has found that people with PKU are a greater risk of depression, although the reasons for this remain unknown. Parents of 13 adolescents with PKU (M = 13.95 years) fi lled out the Children's Depression Inventory; total symptoms of depression were correlated with the participants lifetime blood results (phenylalanine and tyrosine levels). Signifi cant results were: depression and lifetime tyrosine levels; tyrosine levels prior to age 12 years, r= -.584 and r = -.544 (p < .05) respectively. These results support an organic aetiology, in that chronically low tyrosine (= low dopamine) was associated with depression symptoms in this sample. Individuals with PKU provide us with the opportunity to perform a rare natural experiment; their genetic variation leads to neurotransmitter disruptions allowing for tests of association with a range of cognitive and neuropsychological outcomes. This study demonstrated support for an organic basis for depression in this population, however it was dopamine (rather than serotonin) disruption that lead to symptoms of depression. This research will lead to better targeted treatment for depression in PKU, and may have implications for the wider population as well.

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