• Korean Journal of Biological Psychiatry
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• v.19 no.1
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• pp.29-37
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• 2012

The loudness dependence of the auditory evoked potential (LDAEP) has been proposed as a valid biomarker of central serotoninergic activity in humans. The specificity and sensitivity of the LDAEP to changes in serotonergic neurotransmission have recently been explored in many studies about pharmacology and genetics. The majority of evidence for an association between the LDAEP and serotonin activity has come from animal studies. Genetic association studies with the LDAEP have provided conflicting reports with additional evidence outlining sensitivity to other neurotransmitter systems including the dopamine and glutamatergic systems. The LDAEP has been revealed to reflect the pathophysiology of various psychiatric illnesses. There is supporting evidence that major psychiatric disorders have differential LDAEP activities. Overall, the LDAEP shows strong evidence as a potential predictor of antidepressant treatment response. It need to be explored whether the LDAEP could be a biological marker of various psychiatric diseases and treatment prediction of antidepressants and serotonin related drugs.

• Korean Journal of Biological Psychiatry
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• v.19 no.3
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• pp.115-120
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• 2012

Objectives : Event-related potentials have been suggested as an objective marker for brain functions in psychiatric disorders. This study was aimed to investigate the relationships between P300, the mismatch negativity (MMN), the loudness dependence of the auditory evoked potential (LDAEP), demographic and clinical variables including neurocognitive abilities in patients with schizophrenia. Methods : P300, the MMN, and the LDAEP were measured and the Korean Stroop color-word test (K-stroop test) and the Wisconsin Card Sorting Test (WCST) were performed in 43 patients with schizophrenia. The relationship of the latency and amplitude of P300 and the MMN as well as regression slope of the LDAEP with demographic and clinical variables were analyzed by t-test and correlation analyses for categorical and continuous variables, respectively. Results : After controlling for age, the latency of central (Cz) and parietal (Pz) P300 posivitively correlated with GAF at admission (Cz ; ${\gamma}$ = 0.385, p = 0.047, Pz ; ${\gamma}$ = 0.421, p = 0.029). The amplitude of parietal P300 correlated with the correction rate of the K-stroop test (${\gamma}$ = 0.575, p = 0.002). In addition, the frontal (Fz) P300 latency tended to negatively correlated with the correction rate of the WCST (${\gamma}$ = -0.371, p = 0.057). Conclusions : Our findings suggest that the values of P300 latency and amplitude might be correlated with GAF at admission and working memory measured by the K-Stroop test and the WCST. Meanwhile, the MMN and the LDAEP did not correlate with demographic and clinical variables. These results support the results of previous studies showing associations with P300 and impaired cognitive ability.

• Sleep Medicine and Psychophysiology
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• v.21 no.1
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• pp.29-32
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• 2014

Objectives: The aim of current study is to evaluate the relationship between sleep, suicide and serotonin using some scales and loudness dependence of auditory evoked potentials (LDAEP). Methods: Total 65 patients who met the criteria for major depressive disorder were enrolled in current study. The patients were divided into two subgroups according to their insomnia and a history of suicide attempts. The auditory event-related potentials were measured to evaluate LDAEP before beginning antidepressants. Results: The scores of total Beck Depression Inventory (BDI) and BDI item 9 (suicide) were higher in insomnia subgroup than non-insomnia subgroup (respectively, p=0.0033 and p=0.03). However, LDAEP did not differ each other. The subgroup with a history of suicide attempts had a higher score of BDI item 9 than the subgroup without a history of suicide attempts (p=0.00012). There was a tendency for the LDAEP to be higher in the subgroup with a history of suicide attempts ($1.39{\pm}0.94{\mu}V$) than the sub-group without a history of suicide attempts ($1.05{\pm}0.75{\mu}V$), although the difference was not statistically significant (p=0.078). Conclusion: Suicidality was related to insomnia. In addition, there was a tendency for serotonin activity to be lower in the subgroup with a history of suicide attempts. In future, more studies are needed.

• Korean Journal of Biological Psychiatry
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• v.21 no.1
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• pp.14-20
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• 2014

Objectives The current study investigated the putative relationship between chronotype and suicidality or bipolarity in patients with major depressive disorder (MDD). Method Nineteen outpatients who met the criteria for MDD according to the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders-text revision were recruited for the current study. The subjects were divided into two subgroups based on their Basic Language Morningness (BALM) scores (dichotomized according to the median BALM score). The Loudness Dependence of Auditory Evoked Potentials (LDAEP) was evaluated by measuring the auditory event-related potentials before beginning medication with serotonergic agents. In addition, K-Mood Disorder Questionaire (K-MDQ), Beck Scale for Suicidal Ideation (BSS), Beck Hopelessness Scale (BHS), Barratt Impulsiveness Scale (BIS) were applied. Results The K-MDQ, BSS, BHS, BIS score was higher for the eveningness group than for the morningness group. However, the LDAEP, Hamilton Depression Rating Scale, Hamilton Anxiety Scale scores did not differ significantly between them. There were negative correlations between the total BALM score and the total K-MDQ, BSS, and BHS scores (r=-0.64 and p=0.0033, r=-0.61 and p=0.0055, and r=-0.72 and p=0.00056, respectively). Conclusions Depressed patients with eveningness are more vulnerable to the suicidality than those with morningness. Eveningness is also associated with bipolarity.