Bipolar Disorder and the Brain

Bipolar disorder, formerly manic-depressive illness, is defined as a mood disorder characterized by periods of depression alternating with normal periods and periods of intense excitation, or mania.  The DSM-IV criteria for mood disorders are severe disturbances of mood resulting in extreme and inappropriate sadness or elation for extended periods of time.  Manic episodes, characterized by grandiose plans, being uncontrollably hyperactive and excessive euphoria, abruptly alternate with depressive episodes.  The signal transduction in the postsynaptic cell of the monoamine systems is abnormal in mood disorders.  Other areas of the brain affected by the disorder are the prefrontal and anterior cingulate cortex and the amygdala which shows increased blood flow and glucose utilization.  Approximately 2.6% of the population has been diagnosed with a mood disorder.  Bipolar disorder is treated with mood stabilizers, which are drugs that mute the intensity of one pole of the disorder, thus making the other pole less likely to recur.  Lithium which is thought to stimulate the release of serotonin and valproate which increases GABA output are both psychoactive drugs used to treat mood disorders.

            The article that I chose looks at the neurocognitive impairments in functioning in people with Bipolar Spectrum Disorder (BSD) and Major Depressive Disorder.  It is believed that the neural circuits that regulate mood are flawed and that it may be a defective genetic trait.  Some criteria for BSD are: at least one or more recurring major depressive episodes, antidepressant induced mania or hypomania, psychotic major depressive episodes, early age of onset of symptoms, lack of response to medications.  Sixty-three patients who had been diagnosed with MDD and thirty-three control participants were chosen for the study.  The all patients with MDD were given the Hamilton Rating Scale for Depression (HRSD) and the Structured Clinical Interview for DSM-IV (SCID-1) on the day of the cognitive exam to check for euthymia and to be separated into two groups.    42 patients were placed in the MDD group and 21 in the BSD group.  Age, gender and IQ, as well as, symptoms of their disorders were very equal in all pre tests and all patients were classified as being in illness remission.

 Impairments with verbal memory, executive functioning were greater in the BSD group than with the MDD group and the controls.  These neurocognitive abnormalities are all housed in the prefrontal cortex and hippocampal regions.  Research has shown that there may be genetic abnormalities with the neural circuits connecting the prefrontal cortex and the subcortical regions of the brain along with other areas.  Since neurocognitive functioning problems is one of the core symptoms of BSD the results of the study show that those with BSD are greater impaired that those with unipolar depression and MDD, especially in young adults.

Blackwood, D.H.R., Muir, W.J., & Smith, D.J. (2006). Neurocognitive impairment in euthymic young adults with bipolar spectrum disorder and recurrent major depressive disorder.  Bipolar Disorders, 8, 40-46.