Sleep deprivation a possible endophenotype in bipolar disorder
medwireNews: Sleep deprivation appears to play a pivotal role in mood outcomes among the first-degree relatives of patients with bipolar disorder, say researchers who suggest it may represent an endophenotype of the condition.
They found "completely distinct" endocrine mechanisms at play as a result of sleep deprivation in first-degree relatives of patients with bipolar disorder, compared with healthy controls.
"Our findings related to relationships between sleep and endocrine functions may contribute to early detection of the illness [in] high risk individuals, particularly offspring of parents with bipolar disorder," says the team, led by Yavuz Selvi (Selcuk University Medicine Faculty, Konya, Turkey).
The researchers took blood samples from 44 relatives of outpatients with bipolar disorder and 47 mentally healthy controls the morning before and the morning after one night of sleep deprivation from 22.00 to 07.00. The participants also completed the Profile of Mood States (POMS) on both occasions.
There were no significant differences in endocrinology measurements between the two groups before or after sleep deprivation. But increases in diurnal plasma thyroid-stimulating hormone (TSH) and dehydroepiandrosterone-sulfate (DHEA-S) were larger in controls after sleep deprivation than in relatives of bipolar disorder patients.
The researchers report in the Journal of Affective Disorders that the relatives of patients with bipolar disorder had significantly higher scores on the depression-dejection subscale of the POMS before sleep deprivation than did controls. After sleep deprivation, however, scores in the relatives fell to a level similar to that of controls, whereas there was no significant change among controls.
Increases in TSH levels following sleep deprivation were negatively associated with depression-dejection scores, but only among controls.
Among the relatives of patients with bipolar disorder, changes in depression-dejection as well as vigor-activity scores following sleep deprivation negatively correlated with changes in plasma cortisol levels, despite, paradoxically, sleep deprivation not having a significant effect on plasma cortisol levels.
Plasma DHEA-S levels significantly correlated with vigor-activity after sleep deprivation among relatives of bipolar disorder patients, as they were in controls, but significant associations between DHEA-S levels and depression-dejection, anger-hostility, and confusion-bewilderment in relatives before sleep deprivation were no longer significant afterward.
Finally, increases in plasma T3 levels as a consequence of sleep deprivation significantly predicted decreases in fatigue-inertia scores among the relatives of bipolar disorder patients.
The researchers suggest that sleep deprivation may change receptor sensitivity in individuals genetically vulnerable to bipolar disorder, which in turn affects the mechanisms of endocrine functions.
They believe that "clinical assessment of endocrine parameters should be concomitant to psychiatric assessment and primary interventions to endocrine abnormalities can lead to more positive outcomes of psychiatric treatment."
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By Lucy Piper, Senior medwireNews Reporter