PET imaging of depression

Major depressive disorder (MDD) is a mental disorder with high prevalence, often early age of onset, low recovery rates, and high rates of co-morbidity. MDD is strongly linked to anxiety disorders and cognitive impairment. Depression is moderately heritable, and numerous environmental risk factors have been identified. Epigenetic mechanisms play a role in susceptibility to depression. Inflammation (both neuroinflammation and systemic inflammation) has a cause and effect relationship with MDD and several other psychiatric and neurological disorders.

Most MDD patients benefit from treatment with antidepressants that modulate the monoamine system (serotonergic system, dopaminergic system, norephedrine). Psychotherapy and brain stimulation are effective in treatment of depression but with limited availability. Serotonin reuptake inhibitors (SSRIs) are currently the most used antidepressants, followed by norepinephrine reuptake inhibitors (NRIs), or their combination. Ketamine, targeting glutamatergic system, can be useful in treatment of depression. In addition, the opioid system and melatonin/orexin systems are involved in the pathophysiology of MDD. Anti-inflammatory medication may have role as part of treatment.

Structural MRI studies have identified morphological changes in several brain regions. Brain PET imaging has been used to study regional changes in metabolism and neurotransmitter systems in depression and the effects of treatment.

Neuroinflammation in MDD has been studied using TSPO radioligands in humans (Richards et al., 2018) and in animal models (Kopschina Feltes et al., 2019).


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Literature

McIntyre RS, Rong C, Subramaniapillai M, Lee Y (eds): Major Depressive Disorder. Elsevier, 2019. doi: 10.1016/C2017-0-01421-0.



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Updated at: 2021-04-23
Created at: 2021-04-23
Written by: Vesa Oikonen