Suprachiasmatic nucleus functional connectivity related to insomnia symptoms in adolescents with major depressive disorder

Abnormal intrinsic functional network connectivity in adolescent major depressive disorder related to severity of insomnia

BACKGROUNDS

Insomnia is closely associated with depression and plays a critical role in its development. Investigating insomnia-related neuroimaging changes in depression could enhance understanding of the neural mechanisms underlying depression insomnia. However, the brain network mechanism underlying the bidirectional relationship between depression and insomnia in adolescents remains unknown.

METHODS

We recruited 83 drug-naïve adolescents with MDD and classified them into high- (HI-aMDD) and low-insomnia (LI-aMDD) groups based on the Hamilton Depression Rating Scale sleep subscale. Static and dynamic functional network connectivity (FNC) were analyzed in 34 HI-aMDD, 49 LI-aMDD patients, and 59 gender-matched healthy controls (HCs) using independent component analysis. Partial correlation analysis examined the links between FNC differences and clinical variables.

RESULTS

The HI-aMDD patients showed decreased static FNC between the cerebellum network (CeN) and both the dorsal attention (DAN) and frontoparietal networks (FPN) and decreased dynamic CeN-DAN/limbic FNC, compared to both HCs and LI-aMDD. The LI-aMDD patients exhibited decreased static CeN-DAN/FPN connectivity and decreased dynamic CeN-DAN connectivity compared to HCs. These network connectivity alterations were negatively related to insomnia symptoms in the aMDD group.

CONCLUSION

Our study revealed graded static and dynamic CeN-DAN functional connectivity associated with insomnia severity in aMDD patients. High-insomnia aMDD patients showed unique dynamic interactions between CeN and limbic network, highlighting critical neural pathways involved in depression-related insomnia. These findings suggest that cerebellum, dorsal attention and limbic networks may be specifically involved in the pathophysiology of insomnia in adolescent depression and provide new potential treatment targets.

Common and sex-specific differences in hypothalamic subunit volumes and their links with depressive symptoms in treatment-naïve patients with major depressive disorder

The hypothalamus, which consists of histologically and functionally distinct subunits, primarily modulates vegetative symptoms in major depressive disorder (MDD). Sex differences in MDD have been well-documented in terms of illness incidence rates and symptom profiles. However, few studies have explored subunit-level and sex-specific anatomic differences in the hypothalamus in MDD compared to healthy controls (HCs). High-resolution 3D T1-weighted images were obtained from 133 treatment-naïve patients with MDD and 130 age-, sex-, education years-, and handedness-matched HCs. MRI data were preprocessed and segmented into ten bilateral hypothalamic subunits with FreeSurfer software. We tested for both common and sex-specific patterns of hypothalamic anatomic differences in MDD. Regardless of sex, patients with MDD showed significantly smaller volumes in the left anterior-inferior subunit (a-iHyp) and larger volumes in the right posterior subunit (posHyp). The volumes of the left a-iHyp were negatively correlated with sleep disturbance scores in the MDD group. A significant sex-by-diagnosis interaction was observed in the right whole hypothalamus, and subsequent post-hoc analyses revealed that males with MDD showed significantly larger volumes, while females with MDD showed significantly smaller volumes relative to their sex-matched HCs. Common differences in MDD were found in the left anterior-inferior and right posterior hypothalamus that are involved in regulating circadian rhythms and reward, while sex-specific differences in MDD were observed in the right whole hypothalamus. These findings enhance our understanding of distinct hypothalamic subunit related to MDD and shed light on the neurobiology underlying sex-related variations in MDD.

Thyroid Function and Sleep Patterns: A Systematic Review

Hypothyroidism, defined as a low metabolic function of the thyroid gland that results in low thyroid hormone levels, and insomnia, a condition with the inability to sleep, are two distinct conditions with little overlap that have been extensively established. Both conditions have been studied independently in terms of epidemiology, pathophysiology, diagnosis, and management. The exact causal relationship between the two conditions has yet to be elucidated, and a direct underlying pathophysiology has not been pinpointed. To gain further insight into the relationship between hypothyroidism and insomnia, we performed a systematic review to explore this relationship using predetermined guidelines. Out of 59 studies assessed, four studies evaluated the mechanisms of these two potentially comorbid conditions. Our findings suggest that hypothyroidism and insomnia may have a bidirectional relationship, with symptomatic overlap that is tied to increased metabolic comorbidities and hormonal dysregulation. These findings warrant further research to verify these early findings and gain further insight into the relationship between these conditions. A better understanding of the pathophysiology of overlap between these two conditions will help improve diagnosis and target treatment more effectively.

Pathophysiology of cluster headache: From the trigeminovascular system to the cerebral networks

BACKGROUND

Despite advances in neuroimaging and electrophysiology, cluster headache's pathogenesis remains unclear. This review will examine clinical neurophysiology studies, including electrophysiological and functional neuroimaging, to determine if they might help us construct a neurophysiological model of cluster headache.

RESULTS

Clinical, biochemical, and electrophysiological research have implicated the trigeminal-parasympathetic system in cluster headache pain generation, although the order in which these two systems are activated, which may be somewhat independent, is unknown. Electrophysiology and neuroimaging have found one or more central factors that may cause seasonal and circadian attacks. The well-known posterior hypothalamus, with its primary circadian pacemaker suprachiasmatic nucleus, the brainstem monoaminergic systems, the midbrain, with an emphasis on the dopaminergic system, especially when cluster headache is chronic, and the descending pain control systems appear to be involved. Functional connection investigations have verified electrophysiological evidence of functional changes in distant brain regions connecting to wide cerebral networks other than pain.

CONCLUSION

We propose that under the impact of external time, an inherited misalignment between the primary circadian pacemaker suprachiasmatic nucleus and other secondary extra- suprachiasmatic nucleus clocks may promote disturbance of the body's internal physiological clock, lowering the threshold for bout recurrence.

Relationship between cognitive function and brain activation in major depressive disorder patients with and without insomnia: A functional near-infrared spectroscopy (fNIRS) study

BACKGROUND

Patients with major depressive disorder (MDD) frequently present with sleep disturbances and cognitive impairment. The purpose of this study was to investigate whether cognitive impairment is more severe in MDD patients with insomnia, and the underlying neural mechanisms.

METHODS

A total of 41 MDD patients with insomnia and 43 MDD patients without insomnia were recruited. We used functional near-infrared spectroscopy (fNIRS) to assess changes in oxyhemoglobin (Oxy-Hb) concentrations in the brain of patients while performing a verbal fluency task (VFT). Sleep quality was assessed by the Pittsburgh Sleep Quality Index (PSQI), cognitive function by the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), and severity of depression by the Hamilton Depression Scale (HAMD).

RESULTS

Compared to MDD patients without insomnia, those with insomnia had lower scores on the RBANS total and immediate memory, visuospatial/constructional, and delayed memory subscales, as well as lower oxy-Hb concentrations in the bilateral dorsolateral prefrontal cortex (DLPFC) and bilateral medial prefrontal cortex (mPFC).Further correlation analysis showed that there was a significant correlation between the RBANS total score in all brain regions except left mPFC in MDD patients with insomnia(all p < 0.05). Further multiple linear regression showed that Oxy-Hb concentrations of left DLPFC were independently associated with RBANS total score.

CONCLUSION

Our study suggests that MDD patients with insomnia have more cognitive impairment, which is associated with impaired frontal brain activity. Our findings may provide new insights to understand the underlying neural mechanisms of both disorders MDD patients and provide potential clinical value for developing treatment strategies for insomnia in MDD patients.