ABSTRACT
BACKGROUND: Significant differences in clinical manifestations between first-episode and recurrent major depression disorder (FE-MDD/R-MDD) have been demonstrated in previous studies, including the degree of suicide attempt. However, the potential brain mechanism underlying the effect of depressive episode frequency on suicidal ideation (SI) remains unclear. METHODS: In this study, 102 patients with FE-MDD (SI/non-SI: N = 70/32) and 71 matched normal controls (NCs), as well as 75 patients with R-MDD (SI/non-SI: N = 37/38) and 49 matched NCs were screened from the Chinese REST-meta-MDD consortium. T1-weighted and resting-state fMRI images were used to calculate gray matter volume (GMV) and fractional amplitude of low-frequency fluctuations (fALFF), respectively. RESULTS: Group comparisons revealed that FE-MDD showed changes only in GMV, while R-MDD showed changes in both GMV and fALFF compared to NCs. SI-specific GMV decreases were observed in the right cerebellum, superior marginal gyrus, and left middle temporal gyrus in FE-MDD patients, while SI-specific fALFF decreases in bilateral superior frontal gyrus and increases in bilateral cerebellum and left parahippocampal gyrus were obserevd in R-MDD patients. Moreover, a negative correlation was found between GMV value in right cerebellum and HAMD score. CONCLUSIONS: These findings suggest that first-episode and recurrent MDD show different effects on brain structure and function in patients with SI, providing a potential explanation for the distinct clinical manifestations of MDD patients from a brain mechanisms perspective.
Subject(s)
Depressive Disorder, Major , Humans , Depressive Disorder, Major/diagnostic imaging , Suicidal Ideation , Magnetic Resonance Imaging/methods , Brain/diagnostic imaging , Cerebral Cortex/diagnostic imaging , RecurrenceABSTRACT
The verbal fluency test (VFT) is utilized in neuropsychology to evaluate the cognitive function of the prefrontal cortex (PFC) in the human brain. We present a novel Chinese VFT similar to the established Japanese VFT; both tests prompt a syllable to the subject. However, it was uncertain whether the Chinese VFT can activate the PFC and whether PFC activation patterns are similar between the two tests. Here we administered the Chinese VFT to 30 native Chinese speakers and the Japanese VFT to 30 native Japanese speakers. We used near-infrared spectroscopy (NIRS) to observe PFC activation. Then we compared the similarities between the Chinese VFT and the Japanese VFT. The subjects generated an average of 12.8 ± 4.7 words during the Chinese VFT. NIRS indicates that the concentration of oxygenated hemoglobin during the test was significantly higher than those before and after the test. It exhibited similar PFC activation patterns with the Japanese VFT. The novel Chinese VFT can activate the PFC in the human brain effectively in Chinese speakers. Our work thus provides the first validated phonetically cued Chinese VFT, unique from other not strictly phonemic Chinese VFTs, and facilitates the diagnosis of various PFC-related cognitive impairments.
Subject(s)
Cross-Cultural Comparison , Spectroscopy, Near-Infrared/methods , Speech Disorders/physiopathology , Adult , China , Cognitive Dysfunction/physiopathology , Cues , Female , Humans , Japan , Language , Male , Middle Aged , Neuropsychological Tests , Oxyhemoglobins/metabolism , Prefrontal Cortex/physiopathology , Speech Disorders/diagnosis , Verbal Behavior/physiologyABSTRACT
Repetitive transcranial magnetic stimulation (rTMS) has recently been widely employed for the investigation of brain function and treatment of psychiatric and neurological disorders. Although high and low stimulation frequencies are assumed to activate and deactivate brain function, respectively, the optimal parameters of rTMS for treatment of depression have been determined only on the basis of their clinical efficacy. In this study, we administered a 60-s low-frequency rTMS of three grades low intensities over the right dorsolateral prefrontal cortex (DLPFC) in 10 healthy volunteers, and monitored functional changes of the contralateral DLPFC by near-infrared spectroscopy (NIRS) during and immediately after rTMS. Obtained results demonstrated significant [oxy-Hb] decreases during rTMS, and significant differences in the time courses of [oxy-Hb] changes among three stimulus intensities, that is, [oxy-Hb] decreases were most prominent during the latter half of the stimulation and the first 30s of poststimulation only at 15mm condition (58% intensity). These results suggest that monitoring of brain functional changes due to rTMS using NIRS is useful for elucidating the brain mechanisms underlying the clinical effects of rTMS, and the effects of rTMS over contralateral DLPFC are obtained if the stimulus intensities are more than one-half of the motor thresholds.
Subject(s)
Depressive Disorder/therapy , Functional Laterality/radiation effects , Prefrontal Cortex/blood supply , Prefrontal Cortex/radiation effects , Spectroscopy, Near-Infrared/methods , Transcranial Magnetic Stimulation/methods , Adult , Cerebrovascular Circulation/physiology , Cerebrovascular Circulation/radiation effects , Depressive Disorder/physiopathology , Energy Metabolism/physiology , Energy Metabolism/radiation effects , Evoked Potentials, Motor/physiology , Female , Functional Laterality/physiology , Humans , Male , Middle Aged , Oxygen Consumption/physiology , Oxygen Consumption/radiation effects , Oxyhemoglobins/analysis , Oxyhemoglobins/metabolism , Prefrontal Cortex/physiology , Time FactorsABSTRACT
The purpose of this study is to examine the relationship between subjective fatigue and brain function. Twenty-three healthy young volunteers participated in this study. Relationships were investigated between subjective fatigue assessed using visual-analogue scale (VAS) score and sleep duration, and cerebral cortex reactivity during a verbal fluency task by 52-channel near-infrared spectroscopy (NIRS). The VAS score negatively correlated with oxygenated hemoglobin concentration ([oxy-Hb]) increases in the bilateral channels over the regions from the ventrolateral part of the frontal lobe to the upper part of the temporal lobe during the verbal fluency task. Sleep duration in the previous night positively correlated with [oxy-Hb] increases in the bilateral channels over the dorsolateral prefrontal lobe also during the verbal fluency task. No significant correlations between the VAS score and sleep duration in the previous night with [oxy-Hb] increases were found during a control task, the left-finger-tapping task. The subjective feeling of psychological fatigue is related to decreased reactivities in the lateral frontal and superior temporal cortices and is unrelated to sleep duration in the previous night, which is reflected in the reactivity in the dorsolateral prefrontal cortices. These results suggest that transient hypofunction and persistent dysfunction in the lateral prefrontal and temporal lobes are among the brain substrates of fatigue. These also demonstrate the advantage of NIRS for investigating brain function during subjective phenomena such as fatigue because it enables examination in a natural setting.
