The Y-axis represents the rate of relapsing to a non-euthymic state of all subjects euthymic at baseline.
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Euthymic participants with BD and HC differed in all domains.
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The euthymic patients showed deficits in executive function, verbal learning, and dexterity.
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Despite the relative absence of mood symptoms, the euthymic patients manifested residual deficits in social and occupational function.
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The neurobehavioral difficulties seem to be present to a greater extent during acute mood episodes than during euthymic periods.
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Some have not only compared euthymic bipolar patients to control groups but also to schizophrenic patients with mild residual symptoms.
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In some studies, the degree to which patients are well-characterized as euthymic varies, with some investigations clearly indicating that participants have few if any symptoms.
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Various triggers have been associated with switching from euthymic or depressed states into mania. One common trigger of mania is antidepressant therapy. Studies show that the risk of switching while on an antidepressant is between 6-69 percent. Dopaminergic drugs such as reuptake inhibitors and dopamine agonists may also increase risk of switch.
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These groups reported diminished receptive ability in heroin addicts and phencyclidine abusers, contrasted with increased receptivity in cocaine addicts. Men with major depression manifested significantly decreased ability to read nonverbal cues when compared with euthymic men. In some subjects tested for ability to read nonverbal cues, intuitive paradigms were apparently employed while in others a cause and effect approach was used. Subjects in the former group answered quickly and before reinforcement occurred.
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Estrogen therapy appears to have a beneficial influence on mood in depressed and euthymic perimenopausal women. Conversely, research on combined estrogen and progestogen therapy for depressive symptoms in menopausal women is scarce and inconclusive. Some researchers contend that progestogens have an adverse influence on mood and reduce the benefits of estrogens on mood, whereas other researchers maintain that progestogens have no adverse influence on mood. Progesterone differs from progestins in terms of effects in the brain and might have different effects on mood in comparison.
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Cyclothymia, a condition of continuous mood fluctuations, is characterized by oscillating experiences of hypomania and depression that fail to meet the diagnostic criteria for either manic or major depressive episodes. These periods are often interspersed with periods of relatively normal (euthymic) functioning. When a patient presents with a history of at least one episode of both hypomania and major depression, each of which meet the diagnostic criteria, bipolar II disorder is diagnosed. In some cases, depressive episodes routinely occur during the fall or winter and hypomanic ones in the spring or summer.
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Specifically, reduced blood flow to the lateral OFC has been reported, and may reflect dysfunction that leads to the neurocognitive deficits. In novel environments, both bipolar manic and bipolar euthymic people demonstrate increased activity, exploration and linear movement that is greater than controls, people with ADHD and people with schizophrenia. Using this behavioral pattern in "reverse translational" studies, this behavioral abnormality has been associated with the cholinergic-aminergic hypothesis, which postulates elevated dopaminergic signaling in mania. Reducing the function of DAT using pharmacological or genetic means produces a similar behavioral pattern in animal models.
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Hence any condition that is even partly hereditary necessarily manifests structural abnormality at the molecular level. Regardless of whether the actual morphological abnormality can be identified, if a condition has a hereditary component then it has a biological basis. Twin and adoption studies have strongly demonstrated that heredity is a major factor in the etiology of schizophrenia; thus there must be some biological difference between schizophrenics and non-schizophrenics. In relation to major depressive disorder a difference of response between euthymic and depressed individuals to antidepressant drugs and to tryptophan depletion has been demonstrated.
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Reviews have indicated that most individuals diagnosed with bipolar disorder, but who are euthymic (not experiencing major depression or mania), do not show neuropsychological deficits on most tests. Meta-analyses have indicated, by averaging the variable findings of many studies, cognitive deficits on some measures of sustained attention, executive function and verbal memory, in terms of group averages. On some tests, functioning is superior; however, and sub-threshold mood states and psychiatric medications may account for some deficits. A 2010 study found that "excellent performance" at school at age 15–16 was associated in males with a higher rate of developing bipolar disorder, but so was the poorest performance.
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Manic episodes appear to be associated with decreased activation of the right vPFC whereas depressive episodes are associated with decreased activation of the left vPFC. People with bipolar disorder who are in a euthymic mood state show decreased activity in the lingual gyrus compared to people without bipolar disorder. In contrast, they demonstrate decreased activity in the inferior frontal cortex during manic episodes compared to people without the disorder. Similar studies examining the differences in brain activity between people with bipolar disorder and those without did not find a consistent area in the brain that was more or less active when comparing these two groups.
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The distinction between mood and affect in the MSE is subject to some disagreement. For example, Trzepacz and Baker (1993)Trzepacz & Baker (1993) p 39 describe affect as "the external and dynamic manifestations of a person's internal emotional state" and mood as "a person's predominant internal state at any one time", whereas Sims (1995)Sims (1995) p 222 refers to affect as "differentiated specific feelings" and mood as "a more prolonged state or disposition". This article will use the Trzepacz and Baker (1993) definitions, with mood regarded as a current subjective state as described by the patient, and affect as the examiner's inferences of the quality of the patient's emotional state based on objective observation.Supported for example by Mood is described using the patient's own words, and can also be described in summary terms such as neutral, euthymic, dysphoric, euphoric, angry, anxious or apathetic.
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