Heon-Jeong Lee

Association of the RORA Gene Polymorphism and Seasonal Variations in Mood and Behavior

Circadian rhythms have been observed to be disturbed in mood disorders, especially seasonal affective disorder (SAD). Clock related gene variants also have been suggested to be associated with seasonality (seasonal variations in mood and behavior). This study tested the potential association between a length polymorphism of Period3 gene and seasonal variations in mood and behavior. 297 Korean college students were genotyped for the Period3 polymorphism and were for evaluated the seasonal variation by Seasonal Pattern Assessment Questionnaire (SPAQ). The genotype frequencies were 0.76 for 4R/4R, 0.22 for 4R/5R and 0.013 for 5R/5R. The global seasonality score was not different among Period3 gene variants (4R/4R, 4R/5R and 5R/5R) except for sleep length subscore. The 5R/5R genotype showed the higher sleep length subscore than others (p=0.024). The comparison between seasonals (syndromal plus subsyndromal SAD determined by SPAQ) and non-seasonals did not show any significant difference in frequencies of genotypes. These findings suggest that there is a possibility that the investigated Period3 polymorphism may play a partial role in the susceptibility of seasonal variations in a Korean population.

Sleep and sleep disorders in depression

Disturbances of the sleep-wake cycle are very common in depression and serve as a sensitive biological marker of brain function. Insomnia and hypersomnia not only are some of the main symptoms of depression but also are diagnostic criteria of depression in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. These symptoms also influence the quality of life and long-term prognosis of patients with depression. In addition to sleep disturbance as symptoms of depression, primary sleep disorders are frequently comorbid with depression. Therefore, differential diagnosis and management of these conditions are important in the clinic. Sleep disturbances might be used as a biological marker for the occurrence, treatment response, and relapse of depression. The most typical sleep architecture changes in depression are an increase in rapid eye movement (REM) density and a decrease in slow-wave sleep. This REM sleep disinhibition in depression may be related to a predominance of cholinergic activity relative to monoaminergic activity. For patients with depression who experience insomnia, antidepressants, hypnotics, and cognitive behavioral therapy can be used effectively to relieve insomnia. However, since pharmacotherapy for depression and insomnia might degrade sleep quality and/or cause (or aggravate) obstructive sleep apnea, restless legs syndrome, and REM sleep behavior disorder, medication should be used cautiously.