Associated disorders
A single manic episode, in the absence of secondary causes, (i.e., substance use disorders, pharmacologics, or general medical conditions) is often sufficient to diagnose bipolar I disorder. Hypomania may be indicative of bipolar II disorder. Manic episodes are often complicated by delusions and/or hallucinations; and if the psychotic features persist for a duration significantly longer than the episode of typical mania (two weeks or more), a diagnosis of schizoaffective disorder is more appropriate. Certain obsessive-compulsive spectrum disorders as well as impulse control disorders share the suffix "-mania," namely, kleptomania, pyromania, and trichotillomania. Despite the unfortunate association implied by the name, however, no connection exists between mania or bipolar disorder and these disorders. Furthermore, evidence indicates a B12 deficiency can also cause symptoms characteristic of mania and psychosis.Hyperthyroidism can produce similar symptoms to those of mania, such as agitation, elevated mood, increased energy, hyperactivity, sleep disturbances and sometimes, especially in severe cases, psychosis.
A proposed mechanism involves increased excitatory input from the STN to dopaminergic nuclei.There are certain psychoactive drugs that can induce a state of manic psychosis, including: amphetamine, cathinone, cocaine, MDMA, methamphetamine, methylphenidate, oxycodone, phencyclidine, designer drugs, etc.Mania can also be caused by physical trauma or illness. When the causes are physical, it is called secondary mania. Mechanism
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).