The mechanism underlying mania is unknown, but the neurocognitive profile of mania is highly consistent with dysfunction in the right prefrontal cortex, a common finding in neuroimaging studies. Various lines of evidence from post-mortem studies and the putative mechanisms of anti-manic agents point to abnormalities in GSK-3, dopamine, Protein kinase C and Inositol monophosphatase. Meta analysis of neuroimaging studies demonstrate increased thalamic activity, and bilaterally reduced inferior frontal gyrus activation. Activity in the amygdala and other subcortical structures such as the ventral striatum tend to be increased, although results are inconsistent and likely dependent upon task characteristics such as valence. Reduced functional connectivity between the ventral prefrontal cortex and amygdala along with variable findings supports a hypothesis of general dysregulation of subcortical structures by the prefrontal cortex. A bias towards positively valenced stimuli, and increased responsiveness in reward circuitry may predispose towards mania. Mania tends to be associated with right hemisphere lesions, while depression tends to be associated with left hemisphere lesions. Post-mortem examinations of bipolar disorder demonstrate increased expression of Protein Kinase C (PKC). While limited, some studies demonstrate manipulation of PKC in animals produces behavioral changes mirroring mania, and treatment with PKC inhibitor tamoxifen (also an anti-estrogen drug) demonstrates antimanic effects. Traditional antimanic drugs also demonstrate PKC inhibiting properties, among other effects such as GSK3 inhibition. Manic episodes may be triggered by dopamine receptor agonists, and this combined with tentative reports of increased VMAT2 activity, measured via PET scans of radioligand binding, suggests a role of dopamine in mania. Decreased cerebrospinal fluid levels of the serotonin metabolite 5-HIAA have been found in manic patients too, which may be explained by a failure of serotonergic regulation and dopaminergic hyperactivity. Limited evidence suggests that mania is associated with behavioral reward hypersensitivity, as well as with neural reward hypersensitivity. Electrophysiological evidence supporting this comes from studies associating left frontal EEG activity with mania. As left frontal EEG activity is generally thought to be a reflection of behavioral activation system activity, this is thought to support a role for reward hypersensitivity in mania. Tentative evidence also comes from one study that reported an association between manic traits and feedback negativity during receipt of monetary reward or loss. Neuroimaging evidence during acute mania is sparse, but one study reported elevated orbitofrontal cortex activity to monetary reward, and another study reported elevated striatal activity to reward omission. The latter finding was interpreted in the context of either elevated baseline activity (resulting in a null finding of reward hypersensitivity), or reduced ability to discriminate between reward and punishment, still supporting reward hyperactivity in mania. Punishment hyposensitivity, as reflected in a number of neuroimaging studies as reduced lateral orbitofrontal response to punishment, has been proposed as a mechanism of reward hypersensitivity in mania.
symptoms of Mental disorder
symptom of Mental disorder
symptom of Delirium
symptom of Anxiety disorder
symptom of Narcolepsy
symptom of Insomnia
symptom of Conversion disorder
symptoms of Delirium