-
Translational Psychiatry Mar 2021Early detection of patients with late-life depression (LLD) with a high risk of developing dementia contributes to early intervention. Odor identification (OI)...
Early detection of patients with late-life depression (LLD) with a high risk of developing dementia contributes to early intervention. Odor identification (OI) dysfunction serves as a marker for predicting dementia, but whether OI dysfunction increases the risk of dementia in LLD patients remains unclear. The present study aimed to explore the interactive effect of LLD and OI dysfunction on the risk of dementia and its underlying neuroimaging changes. One hundred and fifty-seven LLD patients and 101 normal controls were recruited, and data on their OI, cognition, activity of daily living (ADL), and resting-state functional magnetic resonance imaging were collected. Two × two factorial analyses were used to analyze the interactive effects of LLD and OI dysfunction on neuropsychological and neuroimaging abnormalities. Mediation analyses were used to explore whether abnormalities detected by neuroimaging mediated the the associations between OI and cognition/ADL. The results suggested that LLD and OI dysfunction exhibited additive effects on reduced ADL, global cognition and memory scores, as well as neuroimaging variables including (i) increased fractional amplitude of low-frequency fluctuation (fALFF) in the right orbitofrontal cortex and right precentral cortex, and (ii) increased regional homogeneity (ReHo) in the left hippocampus/fusiform gyrus, etc. In addition, these increased fALFF and ReHo values were associated with reduced neuropsychological scores (ADL, global cognition, memory, and language). Moreover, ReHo of the left hippocampus/fusiform gyrus completely mediated the relationship between OI and ADL, and partially mediated the relationship between OI and global cognition. Overall, mediated by the hypersynchronization of the left hippocampus/fusiform gyrus, OI dysfunction may increase the risk of dementia in LLD patients.
Topics: Brain; Dementia; Depression; Hippocampus; Humans; Magnetic Resonance Imaging; Olfaction Disorders; Temporal Lobe
PubMed: 33731679
DOI: 10.1038/s41398-021-01291-0 -
Neuroreport Jan 2021Sleep disorders and multiple sensory impairments have been noticed as the potential first sign of neurodegenerative diseases such as the Parkinson disease. The...
Sleep disorders and multiple sensory impairments have been noticed as the potential first sign of neurodegenerative diseases such as the Parkinson disease. The relationship between sleep quality and the sensory neural basis would help us consider their combination in early diagnosis. In the present study, 32 out of 45 healthy subjects' resting-state functional magnetic resonance imaging data survived from motion correction and entered into the connectivity analysis. We found that the connectivity between two regions of interest (the left olfactory gyrus and the left superior temporal pole) and the regional homogeneity in the left middle temporal gyrus were negatively correlated with their Pittsburgh sleep quality index. These results suggest that these sensory-related brain regions are related to sleep quality and they may together predict the diseases.
Topics: Adult; Auditory Cortex; Connectome; Female; Functional Neuroimaging; Healthy Volunteers; Humans; Magnetic Resonance Imaging; Male; Neural Pathways; Olfactory Cortex; Parkinson Disease; Proportional Hazards Models; Sleep
PubMed: 33395187
DOI: 10.1097/WNR.0000000000001567 -
Brain Sciences Apr 2023Alzheimer's disease (AD) is associated with the abnormal connection of functional networks. Olfactory impairment occurs in early AD; therefore, exploring alterations in...
Alzheimer's disease (AD) is associated with the abnormal connection of functional networks. Olfactory impairment occurs in early AD; therefore, exploring alterations in olfactory-related regions is useful for early AD diagnosis. We combined the graph theory of local brain network topology with olfactory performance to analyze the differences in AD brain network characteristics. A total of 23 patients with AD and 18 normal controls were recruited for resting-state functional magnetic resonance imaging (fMRI), clinical neuropsychological examinations and the University of Pennsylvania Smell Identification Test (UPSIT). Between-group differences in the topological properties of the local network were compared. Pearson correlations were explored based on differential brain regions and olfactory performance. Statistical analysis revealed a correlation of the degree of cognitive impairment with olfactory recognition function. Local node topological properties were significantly altered in many local brain regions in the AD group. The nodal clustering coefficients of the bilateral temporal pole: middle temporal gyrus (TPOmid), degree centrality of the left insula (INS.L), degree centrality of the right middle temporal gyrus (MTG.R), and betweenness centrality of the left middle temporal gyrus (MTG.L) were related to olfactory performance. Alterations in local topological properties combined with the olfactory impairment can allow early identification of abnormal olfactory-related regions, facilitating early AD screening.
PubMed: 37190596
DOI: 10.3390/brainsci13040631 -
Brain and Behavior May 2021Pathological abnormalities first appear in the medial temporal regions including entorhinal cortex and parahippocampus in patients with Alzheimer's disease. Previous...
INTRODUCTION
Pathological abnormalities first appear in the medial temporal regions including entorhinal cortex and parahippocampus in patients with Alzheimer's disease. Previous studies showed that olfactory decline in elderly subjects was associated with volume reductions in the left hippocampus and left parahippocampus without cognitive impairment. The aim of this study is to investigate the link between olfaction and volume reductions in the medial temporal regions including the parahippocampus, entorhinal cortex, and hippocampal subfields.
METHOD
27 elderly subjects and 27 young controls were measured olfaction acuity, cognitive function, and structural magnetic resonance imaging. Image processing and gray matter volumetric segmentation were performed with FreeSurfer. Volume data were analyzed with SPSS Statistics software.
RESULTS
Interesting results of this study were that volume reduction in the entorhinal cortex was not directly linked with declining olfactory ability. Volume reduction in the left entorhinal cortex was correlated with volume reduction in the left parahippocampus and dentate gyrus. However, left parahippocampus volume reduction had the greatest impact on olfactory decline, and the entorhinal cortex and dentate gyrus might additionally contribute to olfactory decline.
CONCLUSION
Our results indicate that olfactory decline may be directly reflected in the medial temporal regions as reduced parahippocampus volumes, rather than as morphological changes in the entorhinal cortex and hippocampus. The parahippocampus may play an important role in the association between memory retrieval and olfactory identification.
Topics: Aged; Entorhinal Cortex; Hippocampus; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Smell
PubMed: 33769719
DOI: 10.1002/brb3.2115 -
Neuroscience Letters Nov 2019New neurons are continuously added in the dentate gyrus of the hippocampus, the olfactory bulb and the hypothalamus of mammalian brain. In sheep, while the control of...
New neurons are continuously added in the dentate gyrus of the hippocampus, the olfactory bulb and the hypothalamus of mammalian brain. In sheep, while the control of adult neurogenesis by the social environment or the photoperiod has been the subject of several studies, its regulation by intrinsic factors, like hormones or neurotransmitters is less documented. We addressed this question by investigating the effects of central oxytocin administration on hippocampal, olfactory and hypothalamic neurogenesis. Endogenous markers, Ki67, Sox2 and DCX were used to assess cell proliferation, progenitor cells density and cell survival respectively in non-gestant ewes receiving a steroid treatment followed by intracerebroventricular injections of either oxytocin or saline. The results showed that oxytocin treatment significantly decreases the density of neuroblasts in the olfactory bulb, increases the density of neuroblasts in the ventromedian nucleus of the hypothalamus while no change is observed in both ventral and dorsal dentate gyrus. In addition, no change in the density of progenitor cells is found in the three neurogenic niches. These findings show for the first time that in females, oxytocin can regulate adult neurogenesis by acting on neuroblasts but not on progenitor cells and that this regulation is region specific.
Topics: Animals; Cell Count; Cell Proliferation; Cell Survival; Dentate Gyrus; Female; Infusions, Intraventricular; Neural Stem Cells; Neurogenesis; Olfactory Bulb; Oxytocin; Sheep; Ventromedial Hypothalamic Nucleus
PubMed: 31562884
DOI: 10.1016/j.neulet.2019.134520 -
Neurological Research Apr 2023We investigated the peripheral and central smell regions in patients with idiopathic intracranial hypertension (IIH) by cranial MRI.
OBJECTIVES
We investigated the peripheral and central smell regions in patients with idiopathic intracranial hypertension (IIH) by cranial MRI.
METHODS
In this retrospective study, cranial MRI images of 43 adult patients with IIH (Group 1) and 43 healthy adults without IIH (Group 2) were included. In both groups, peripheral [Olfactory bulb (OB) volume and Olfactory sulcus (OS) depth] and central smell regions (insular gyrus and corpus amygdala area, and thalamus volume) were measured in cranial MRI.
RESULTS
Bilateral OB volume and insular gyrus area, and right corpus amygdala and thalamus volumes of the IIH group were significantly lower than those of the control group (p < 0.05). In the IIH group, OB volume of the right side was significantly lower, and insular gyrus area of the right side was significantly higher than those of the left side (p < 0.05). In the IIH group, there were positive correlations between OB volumes; OS depths; insular gyrus areas; corpus amygdala areas; and thalamus volumes bilaterally (p < 0.05). In older patients, right OS depth and right corpus amygdala area decreased (p < 0.05).
CONCLUSION
In conclusion, IIH may be related to olfactory impairment. Cranial MRI images showed a decrease in peripheral (OB volume) and central (insular gyrus and corpus amygdala area and thalamus volume) smell regions. To prevent olfactory impairment in IIH patients, treatment should be done in IIH patients to decrease intracranial pressure. It is very important to prevent the circulation of CSF with increased pressure between the sheets of the olfactory nerve in IIH patients.
Topics: Adult; Humans; Aged; Smell; Pseudotumor Cerebri; Retrospective Studies; Olfaction Disorders; Magnetic Resonance Imaging; Olfactory Bulb; Intracranial Hypertension
PubMed: 36373831
DOI: 10.1080/01616412.2022.2146261 -
Frontiers in Aging Neuroscience 2021To explore the relationship between white matter changes and olfactory ability among patients with mild cognitive impairment (MCI) and to develop a tool to predict the...
To explore the relationship between white matter changes and olfactory ability among patients with mild cognitive impairment (MCI) and to develop a tool to predict the development of Alzheimer's disease among patients with MCI. The Montreal Cognitive Assessment (MoCA) was used for cognitive assessments, and the 70% isopropanol test paper was used to evaluate olfactory function. Tract-based spatial statistics, based on the diffusion tensor imaging technology, were used to obtain relevant parameters, and behavioral and imaging results were compared between patients with MCI ( = 36) and healthy older adults ( = 32). The olfactory ability of MCI patients was lower overall, which was positively correlated with the MoCA score. Fractional anisotropy (FA) changes significantly of all parameters. Lower FA regions were mainly located in the corpus callosum, the orbitofrontal gyrus, and the left occipital lobe. The olfactory score was significantly correlated with the FA value of the orbitofrontal gyrus. Fibrous connections in several brain regions, such as the entorhinal cortex, were stronger in patients with MCI. The olfactory ability of MCI patients in our group was positively correlated with the neuropsychological scale results. Impairment in olfactory function was superior to memory deficits for predicting cognitive decline among cognitively intact participants. The fibrous connections in several brain regions, such as the entorhinal cortex, were higher in patients with MCI, which suggested that there may be a compensatory mechanism in the olfactory pathway in MCI patients. The decline in olfactory function may be a significant and useful indicator of neuropathological changes in MCI patients and an effective marker for the development of cognitive decline and dementia.
PubMed: 34887745
DOI: 10.3389/fnagi.2021.765432 -
Neuroscience Letters Jul 2007The hippocampal dentate gyrus is a major recipient of olfactory input in rodents, via connections from the olfactory (piriform) cortex and the olfactory bulb to the...
The hippocampal dentate gyrus is a major recipient of olfactory input in rodents, via connections from the olfactory (piriform) cortex and the olfactory bulb to the entorhinal cortex. Given this connectivity and the known role of activity in dentate gyrus granule cell survival, the present experiment examined the immediate effects of loss of olfactory input to the hippocampus on apoptosis. Adults rats underwent unilateral or bilateral olfactory bulb ablations (OBX), and allowed to recover 24-72 h before the piriform cortex and hippocampal dentate gyrus were processed for terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling [TUNEL] of apoptotic cells. OBX transiently increased TUNEL-positive cells in the ipsilateral piriform cortex and dentate gyrus. Increased TUNEL-labeling was apparent within 24h in both structures, but was more extensive and prolonged in piriform cortex. The results suggest a trans-synaptic regulation of cell survival through at least two synapses.
Topics: Animals; Apoptosis; Cell Count; Cell Death; Cell Nucleus; Cerebral Cortex; Dentate Gyrus; Hippocampus; In Situ Nick-End Labeling; Male; Olfactory Bulb; Rats; Rats, Long-Evans; Smell
PubMed: 17597296
DOI: 10.1016/j.neulet.2007.05.041 -
Zhonghua Er Bi Yan Hou Tou Jing Wai Ke... Jul 2018To analyze the activation of brain regions associated with olfactory in patients with mild cognitive impairment (MCI) by olfactory functional magnetic resonance imaging...
To analyze the activation of brain regions associated with olfactory in patients with mild cognitive impairment (MCI) by olfactory functional magnetic resonance imaging (fMRI). Twenty six patients with MCI were compared with twenty six controls in the dementia center of Tianjin HuanHu hospital in terms of olfactory function T&T testing, the differences between the activation of the whole brain and region of interest associated with olfactory (bilateral primary olfactory cortex(POC), bilateral hippocampus, bilateral orbital frontal gyrus) by olfactory stimulator using event correlation design for olfactory fMRI scanning. To analyze the correlation between the number of activator in POC and the threshold of olfactory discriminate as well as the severity of cognitive impairment.SPSS 19.0 software was used for the statistical analysis. T&T olfactory testing revealed that MCI patients had higher scores than controls (3.57±1.29 (±) 1.02±0.35, =4.372, <0.05). The activation range of whole brain in MCI patients was less than controls (pleasant odor (po) 147.36±21.45 323.11±39.76, unpleasant odor (upo) 201.86±24.93 447.73±57.22, (po)=4.241, (upo)=5.365, both <0.05). The activation range of whole brain in inhaling unpleasant odor was more than pleasant odor in controls (447.73±57.22 323.11±39.76, =3.936, <0.05). The number of activator in ROI(awo) in MCI patients was less than controls (pleasant odor (po) 51.0[8.0, 109.0]([(25), (75)]) 135.0[21.0, 321.5], unpleasant odor (upo) 65.0[6.0, 158.0] 205.0[36.5, 491.0], (po)=-2.199, (upo)=-2.216, both <0.05). The number of activator in POC in MCI patients was less than controls (pleasant odor (po) 19.0[4.0, 35.5] 46.0[9.0, 118.5], unpleasant odor (upo) 26.0[2.0, 51.0] 79.0[17.5, 189.0], (po)=-1.898, (upo)=-2.167, both <0.05). The number of activator in POC was negatively correlated with olfactory discriminate threshold in MCI patients ((po)=-0.415, (upo)=-0.409, both <0.05). The number of activator in POC was positively correlated with MoCA in MCI patients ((po)=0.289, (upo)=0.296, both <0.05). Olfactory fMRI can objectively assess the olfactory function in MCI, it is a imaging indicator with neuropsychological tests for detection in MCI, the number of activator in POC can reflect the severity of MCI.
Topics: Brain; Case-Control Studies; Cognitive Dysfunction; Humans; Magnetic Resonance Imaging; Neuropsychological Tests; Odorants; Olfaction Disorders; Smell
PubMed: 30032492
DOI: 10.3760/cma.j.issn.1673-0860.2018.07.004 -
Frontiers in Neuroscience 2022To investigate the alteration of cerebral blood flow (CBF) and its connectivity patterns in olfactory-related regions of type 2 diabetes mellitus (T2DM) patients using...
To investigate the alteration of cerebral blood flow (CBF) and its connectivity patterns in olfactory-related regions of type 2 diabetes mellitus (T2DM) patients using arterial spin labeling (ASL). Sixty-nine patients with T2DM and 63 healthy controls (HCs) underwent ASL scanning using 3.0T magnetic resonance imaging. We compared the CBF values of the olfactory-related brain regions between the two groups and analyzed the correlation between their changes and clinical variables. We also used these regions as seeds to explore the differences in CBF connectivity patterns in olfactory-related brain regions between the T2DM patients and HCs. Compared with the HC group, the CBF of the right orbital part of the inferior frontal gyrus (OIFG), right insula, and bilateral olfactory cortex was decreased in the T2DM patients. Moreover, the duration of the patients was negatively correlated with the CBF changes in the right OIFG, right insula, and right olfactory cortex. The CBF changes in the right OIFG were positively correlated with the Self-Rating Depression Scale scores, those in the right insula were negatively correlated with the max blood glucose of continuous glucose, and those in the right olfactory cortex were negatively correlated with the mean blood glucose of continuous glucose. In addition, the T2DM patients also showed decreased CBF connectivity between the right OIFG and the left temporal pole of the middle temporal gyrus and increased CBF connectivity between the right medial orbital part of the superior frontal gyrus and the right orbital part of the superior frontal gyrus and between the right olfactory cortex and the bilateral caudate and the left putamen. Patients with T2DM have decreased CBF and altered CBF connectivity in multiple olfactory-related brain regions. These changes may help explain why olfactory dysfunction occurs in patients with T2DM, thus providing insights into the neuropathological mechanism of olfactory dysfunction and cognitive decline in T2DM patients.
PubMed: 35898415
DOI: 10.3389/fnins.2022.904468