Cerebral blood flow and metabolism in late-life depression and dementia

Serum proteomic biomarker investigation of vascular depression using data-independent acquisition: a pilot study

Background

Vascular depression (VaD) is a depressive disorder closely associated with cerebrovascular disease and vascular risk factors. It remains underestimated owing to challenging diagnostics and limited information regarding the pathophysiological mechanisms of VaD. The purpose of this study was to analyze the proteomic signatures and identify the potential biomarkers with diagnostic significance in VaD.

Methods

Deep profiling of the serum proteome of 35 patients with VaD and 36 controls was performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Functional enrichment analysis of the quantified proteins was based on Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, and Reactome databases. Machine learning algorithms were used to screen candidate proteins and develop a protein-based model to effectively distinguish patients with VaD.

Results

There were 29 up-regulated and 31 down-regulated proteins in the VaD group compared to the controls (|log2FC| ≥ 0.26, p ≤ 0.05). Enrichment pathways analyses showed that neurobiological processes related to synaptic vesicle cycle and axon guidance may be dysregulated in VaD. Extrinsic component of synaptic vesicle membrane was the most enriched term in the cellular components (CC) terms. 19 candidate proteins were filtered for further modeling. A nomogram was developed with the combination of HECT domain E3 ubiquitin protein ligase 3 (HECTD3), Nidogen-2 (NID2), FTO alpha-ketoglutarate-dependent dioxygenase (FTO), Golgi membrane protein 1 (GOLM1), and N-acetylneuraminate lyase (NPL), which could be used to predict VaD risk with favorable efficacy.

Conclusion

This study offers a comprehensive and integrated view of serum proteomics and contributes to a valuable proteomics-based diagnostic model for VaD.

Association between depressive symptoms and long-term heart rate variability in older women: Findings from a population-based cohort

INTRODUCTION

Cross-sectional studies highlighted changes in autonomic nervous system (ANS) activity in geriatric depression. However, few longitudinal studies assessed this link which remains still debated. We examined the longitudinal association between lifetime depression history, current depressive disorders, and the evolution of ANS activity in older community women.

METHODS

The present data stemmed from the PROOF study, a population-based cohort of 1011 community-dwellers followed-up at 2-year intervals for 10 years. Only data from female participants was analyzed (n = 508, mean age 68.5 ± 0.88 years), as very few men had depression in our population. Depressive symptoms and depression history were collected at baseline. Participants were classified in four groups according to presence or absence of history of depression (HD) or current depressive symptomatology (CD): HD+/CD+, HD-/CD+, HD+/CD- and HD-/CD-. ANS activity was assessed during the follow-up through 24-h heart rate variability (HRV). Longitudinal associations between depressive status and HRV indices during the follow-up were investigated using multivariate linear mixed models.

RESULTS

Compared to HD-/CD- group, women belonging to HD-/CD+ group had greater baseline parasympathetic tone, as measured by lower LF index and LF/HF balance. The longitudinal analysis exhibited a significant enhancement of LF/HF balance with time, measuring an increase of sympathetic tone in HD-/CD+ group.

CONCLUSION

Our findings suggest that late-onset depressive symptoms may be associated with subsequent autonomic dysregulation in older women. These results highlight the importance of detecting and managing depressive symptoms to limit their consequences on ANS functioning, and the risk of cardiovascular events.

An overview of the molecular and physiological antidepressant mechanisms of physical exercise in animal models of depression

BACKGROUND

Depression is a global disease that affects the physical and mental health of people of all ages. Non-pharmacological and unconventional methods of treatment, such as regular physical exercise, have been recommended to treat depression.

METHODS

Here, we briefly review the literature about the physiological and molecular mechanisms of exercise antidepressants in depressive-like behavior in animal models of depression.

RESULTS

The main hysiological and molecular mechanisms of physical exercise in depression include blood flow changes in several areas of the brain, increase in brain serotonin synthesis, increase in antioxidant enzymes, increase in serum and brain brain-derived neuro factor (BDNF) levels, decrease in cortisol levels and reduced inflammation in peripheral and brain tissues. Physical exercise also leads to increased activation of the phosphatidylinositol-3-kinase (PI3K), PGC-1α/FNDC5/Irisin pathway, BDNF concentrations (serum and cerebral), extracellular signal-regulated kinase and cAMP-response element binding protein (mainly in neurons of the hippocampus and prefrontal cortex), which together contribute to fight or inhibit the development of depression symptoms. These molecular and physiological mechanisms work in synchrony, further enhancing their effects.

CONCLUSION

Physical exercise can be used as a safe and effective non-pharmacological treatment in depression.

The double burden of age and major depressive disorder on the cognitive control network

Poor cognitive control (CC) is common among older individuals with major depressive disorder (OMDD). At the same time, studies of CC in OMDD with fMRI are relatively limited and often have small samples. The present study was conducted to further examine poor CC in OMDD with early onset depression, as well as to investigate the interactive effects of MDD and aging on cognitive control. Twenty OMDD, 17 older never-depressed comparisons (ONDC), 16 younger adults with MDD (YMDD), and 18 younger never-depressed comparisons (YNDC) participated. All participants completed the Go level of the Parametric Go/No-Go Test, which requires sustained attention and inhibitory control while undergoing functional MRI (fMRI). YNDC were faster in reaction times (RTs) to go targets relative to the other 3 groups, and the YMDD group was faster than the OMDD group. fMRI effects of both age and diagnosis were present, with greater activation in MDD, and in aging. Additionally, the interaction of age and MDD was also significant, such that OMDD exhibited greater recruitment of fronto-subcortical regions relative to older comparisons. These results are consistent with prior research reporting that OMDD recruit more fronto-striatal regions in order to perform at the same level as their never-depressed peers, here on a task of sustained attention and inhibitory control. There may be an interaction of cognitive aging and depression to create a double burden on the CC network in OMDD, including possible fronto-striatal compensation during CC that is unique to OMDD, as younger MDD individuals do not show this pattern.

Functional neuroimaging in geriatric depression

Abnormalities in specific cerebral networks likely confer vulnerability that increases the susceptibility for development of geriatric depression and affect the course of symptoms. Functional neuroimaging enables the in vivo identification of alterations in cerebral function that characterize disease vulnerability and contribute to variability in depressive symptoms and antidepressant response. Judicious use of functional neuroimaging tools can advance pathophysiologic models of geriatric depression. Furthermore, geriatric depression provides a logical context within which to study the role of specific functional abnormalities in both antidepressant response and key behavioral and cognitive abnormalities of mood disorders.

Amygdalae morphometry in late-life depression

OBJECTIVE

The amygdalae have been a focus of mood disorder research due to their key role in processing emotional information. It has been long known that depressed individuals demonstrate impaired functional performance while engaged in emotional tasks. The structural basis for these functional differences has been investigated via volumetric analysis with mixed findings. In this study, we examined the morphometric basis for these functional changes in late-life depression (LLD) by analyzing both the size and shape of the amygdalae with the hypothesis that shape differences may be apparent even when overall volume differences are inconsistent.

METHODS

Magnetic resonance imaging data were acquired from 11 healthy, elderly individuals and 14 depressed, elderly individuals. Amygdalar size was quantified by computing total volume and amygdalar shape was quantified with a shape analysis method that we have developed.

RESULTS

No significant volumetric differences were found for either amygdala. Nevertheless, localized regions of significant shape variation were detected for the left and right amygdalae. The most significant difference was contraction (LLD subjects as compared to control subjects) in a region typically associated with the basolateral nucleus, which plays a key role in emotion recognition in neurobiologic models of depression.

CONCLUSIONS

In this LLD study, we have shown that, despite insignificant amygdalar volumetric findings, variations of amygdalar shape can be detected and localized. With further investigation, morphometric analysis of various brain structures may help elucidate the neurobiology associated with LLD and other mood disorders.

The functional neuroanatomy of geriatric depression

OBJECTIVE

Positron Emission Tomography (PET) studies of cerebral glucose metabolism have demonstrated sensitivity in evaluating the functional neuroanatomy of treatment response variability in depression, as well as in the early detection of functional changes associated with incipient cognitive decline. The evaluation of cerebral glucose metabolism in late life depression may have implications for understanding treatment response variability, as well as evaluating the neurobiological basis of depression in late life as a risk factor for dementia.

METHODS

Sixteen patients with geriatric depression and 13 comparison subjects underwent resting PET studies of cerebral glucose metabolism, as well as magnetic resonance (MR) imaging scans to evaluate brain structure.

RESULTS

Cerebral glucose metabolism was elevated in geriatric depressed patients relative to comparison subjects in anterior (right and left superior frontal gyrus) and posterior (precuneus, inferior parietal lobule) cortical regions. Cerebral atrophy (increased cerebrospinal fluid [CSF] and decreased grey and white matter volumes) were observed in some of these regions, as well. Regional cerebral metabolism was positively correlated with severity of depression and anxiety symptoms.

CONCLUSIONS

In contrast to decreased metabolism observed in normal aging and neurodegenerative conditions such as Alzheimer's disease, cortical glucose metabolism was increased in geriatric depressed patients relative to demographically matched controls, particularly in brain regions in which cerebral atrophy was observed, which may represent a compensatory response.

Heart rate variability in depressed elderly

OBJECTIVE

The present study examines a measure of cardiac autonomic function, the heart rate variability (HRV), in a group of depressed elderly. Cardiac autonomic abnormalities have been implicated as a potential mediator of cardiovascular events and sudden death in depression. Because aging is associated with decreased cardiac vagal activity, it is possible that autonomic abnormalities are even more pronounced in the older depressed patients.

DESIGN

Cross-sectional comparison between those with or without depression. The groups were compared using the Wilcoxon matched-pair sign-rank test.

SETTING

Advanced Center for Interventions and Services Research for Late-Life Mood Disorders at University of Pittsburgh Medical Center.

PARTICIPANTS

Fifty-three patients with major depression (mean age: 73.3; SD: 7.4; range: 60-93) and an equal number of age and gender-matched subjects as a comparison group.

INTERVENTION

None.

MEASUREMENTS

Time domain and frequency domain measures of HRV.

RESULTS

The groups did not differ in any of the time domain or frequency domain measures of HRV. As expected, subjects without depression displayed decreasing cardiac vagal function with aging (Spearman correlation coefficient r(s) = -0.33, p = 0.02). However, there was no significant change in vagal function with age in the depressed (r = 0.12, p= 0.38). Post-hoc analysis using Fisher's z(r) transformation revealed that the relationship between age and cardiac vagal function was significantly different between the groups (z = 2.32, p = 0.02).

CONCLUSIONS

Our findings suggest that age has differential influence on vagal function in individuals with and without depression, a difference with implications for cardiovascular disease risk in depression. Prospective studies of cardiac vagal activity in depressed patients with or without preexisting cardiac disease in different age groups are needed to replicate and extend these findings.

Apathy and depression in Alzheimer's disease are associated with functional deficit and psychotropic prescription

BACKGROUND

Apathy and depression are the most common neuropsychiatric features in Alzheimer's disease (AD). The clinical and functional specific correlates of these syndromes are not well known independently from cognitive deficits and other behavioral disturbances.

MATERIAL AND METHODS

Six hundred and eighty-six patients diagnosed with possible or probable AD were included in a prospective multicenter study (REAL-FR). They had an assessment of their cognitive and functional status. Neuropsychiatric symptoms were assessed with the Neuropsychiatric Inventory (NPI) and caregiver's burden was measured with Zarit's Burden Scale.

RESULTS

A majority of patients at any stage of the disease presented with one or several behavioral and psychological disturbances. Apathy concerned 43% of patients and, with or without depression, was associated with more pronounced deficits in global cognition, everyday life and instrumental abilities, nutritional status and with a higher burden level. A high level of psychotropic prescription, especially with antidepressant, was observed in patients with apathy. In a multivariate analysis taking into account the cognitive and functional variables of AD, apathy and depression were the only significant predictors of psychotropic prescription.

CONCLUSION

Some negative neuropsychiatric symptoms such as apathy and depression have a specific relation with functional and therapeutic outcomes of AD, independently from cognitive status. Further studies are needed to establish if apathy represents a particularly severe phenotype of AD.

Hypofrontality and microvascular dysregulation in remitted late-onset depression assessed by functional near-infrared spectroscopy

Accumulated evidence suggests the involvement of vascular factors in late-onset depression. Late-onset depression has characteristics of poor outcome, cognitive decline, and high prevalence rather than early-onset depression. The aim of the present study was to determine whether or not the functional hypofrontality--that is, hypoperfusion and hypometabolism in the frontal lobes-seen in late-onset depression is a trait-dependent abnormality of microvascular regulation. This study was conducted on 10 patients with remitted late-onset major depressive disorder (MDD) and 10 healthy volunteers matched for vascular factors and subcortical, or white matter, hyperintensities (WMH). Using near-infrared spectroscopy combined with magnetic resonance imaging, we investigated the microvascular reactivity in the prefrontal cortex during a cognitive task and during carbon dioxide (CO(2)) inhalation. Activation of the prefrontal cortex during the cognitive task was significantly less in patients as compared with controls, although task performance was not significantly different between the two groups. In the patients, a tendency of negative correlation between the reduced prefrontal activation during a cognitive task and the severity of hyperintensity in periventricular region was observed. Vasomotor reactivity to CO(2) inhalation was significantly lower in the patients than in the controls. Although there was no significant association between the activation during the cognitive and that during the CO(2) inhalation task, the present results suggest that prefrontal microvascular dysregulation as shown by NIRS is involved in the pathophysiological basis of functional hypofrontality in late-onset depression. This finding will provide a new framework for the development of diagnostic methods, treatments, and preventive strategies against late-onset depression.

Acute left prefrontal transcranial magnetic stimulation in depressed patients is associated with immediately increased activity in prefrontal cortical as well as subcortical regions

BACKGROUND

Focal prefrontal cortex repetitive transcranial magnetic stimulation (rTMS) was originally investigated as a potential antidepressant under the assumption that in depressed patients, prefrontal cortex stimulation would produce changes in connected limbic regions involved in mood regulation.

METHODS

Fourteen adult patients with depression were scanned in a 1.5-T scanner using interleaved rTMS (1 Hz) applied on the left prefrontal cortex over 7.35 min. Images were analyzed with Statistical Parametric Mapping 2b and principal component analysis.

RESULTS

Over the left prefrontal cortex, 1-Hz TMS was associated with increased activity at the site of stimulation as well as in connected limbic regions: bilateral middle prefrontal cortex, right orbital frontal cortex, left hippocampus, mediodorsal nucleus of the thalamus, bilateral putamen, pulvinar, and insula (t = 3.85, p <.001). Significant deactivation was found in the right ventromedial frontal cortex.

CONCLUSIONS

In depressed patients, 1-Hz TMS at 100% motor threshold over the left prefrontal cortex induces activation underneath the coil, activates frontal-subcortical neuronal circuits, and decreases activity in the right ventromedial cortex. Further work is needed to understand whether these immediate changes vary as a function of TMS use parameters (intensity, frequency, location) and whether they relate to neurobiologic effects and antidepressant mechanisms of TMS.

Does antidepressant therapy improve cognition in elderly depressed patients?

OBJECTIVES

To analyze the effects of antidepressants on cognitive functioning in elderly depression.

METHODS

Data were pooled for elderly participants with major depression from two double-blind 12-week studies (n = 444) comparing sertraline to fluoxetine and to nortriptyline. A cognitive battery was performed pre-treatment and post-treatment that included the Shopping List Task (SLT), which quantifies short-term and long-term memory storage and retrieval, and the Digit Symbol Substitution Test (DSST), which measures visual tracking, motor performance, and coding.

RESULTS

Older age, male gender, higher systolic blood pressure, and higher illness severity were associated with lower performance on specific cognitive measures at baseline. For the entire group, improved depression and a lower anticholinergic side effect (dry mouth and constipation) severity were associated with statistically significant improvement in the SLT and DSST. The correlations between improvements in depression and improvement in tested cognitive function were highest for sertraline followed by nortriptyline and then fluoxetine.

CONCLUSIONS

Acute improvement in depression is associated with cognitive improvement as measured by the SLT and DSST. Prospective studies are warranted to study the effects of potential differences among antidepressant therapies on long-term cognitive outcomes in geriatric depression.

Late-life depression: its oral health significance

Late-life depression (LLD) initially occurs after age 65 and is a major public health concern because elderly people who are at high risk constitute an ever-expanding segment of the population. LLD is a mental illness in which mood, thought content, and behavioural patterns are impaired, causing individual distress, compromising social function and impairing self-maintenance skills (e.g. bathing, dressing, hygiene). It is characterised by marked sadness, or a loss of interest or pleasure in daily activities and may be accompanied by weight change, sleep disturbance, fatigue, difficulty concentrating, and high suicide rate. Individuals under treatment for LLD and those whose illness has not been diagnosed or treated often present to the dentist with significant oral disease. LLD is frequently associated with a disinterest in performing oral hygiene, a cariogenic diet, diminished salivary flow, rampant dental decay, advanced periodontal disease, and oral dysesthesias. Many medications used to treat the disease magnify the xerostomia and increase the incidence of dental disease. Appropriate dental management necessitates a vigorous preventive dental education programme, the use of artificial salivary products, antiseptic mouthwash, daily fluoride mouthrinse and special precautions when administering local anaesthetics with vasoconstrictors and prescribing analgesics.

Cerebral blood flow in depressed patients: a methodological comparison of statistical parametric mapping and region of interest analyses

Functional brain imaging has assumed a leading role in neuropsychiatric research. However, findings reported for mental disorders often vary. Whether this reflects diversity in pathophysiology or heterogeneity of imaging techniques and data-analytic procedures is still unknown. This study compares region of interest (ROI) and statistical parametric mapping (SPM) analyses of a Tc99m-HMPAO single photon emission computed tomography (SPECT) imaging study of 23 depressed and 21 control subjects. Reduced regional cerebral blood flow (rCBF) was demonstrated by both methods in the right parietal and occipital lobes, but additional regions were identified only on ROI analysis (left temporal) and only on SPM analysis (left parietal). To investigate the contribution of SPM spatial normalization to these discrepancies, further ROI analyses were performed, applying the original ROI templates to normalized images, and applying regions identified by SPM to the original images. This study demonstrated considerable overlap in findings of SPM and ROI analyses. Differences between these methods may be mostly related to subjective placement of ROIs in ROI analysis, and standardized warping inherent in normalization in SPM. Given the advantages and drawbacks of each procedure, the choice of methodology should be determined in accordance with the study design, and complementary use of both methods may be considered.

Late-life depression: psychopathology, medical interventions, and dental implications

BACKGROUND

Late-life depression (LLD) initially occurs after age 65 years and is a major public health concern because the elderly who are at high risk constitute an ever-expanding segment of the population. LLD is a mental illness in which mood, thought content, and behavioral patterns are impaired, causing the individual distress, compromising social function, and impairing self-maintenance skills (eg, bathing, dressing, hygiene). LLD characterized by marked sadness or a loss of interest or pleasure in daily activities and may be accompanied by weight change, sleep disturbance, fatigue, difficulty in concentration, and a high suicide rate. Diagnosis of LLD is sometimes complicated by a denial of mood change and an inability to distinguish symptoms of a concurrent physical illness from those of a depressive etiology. The disorder is most frequently treated with antidepressant medications, and although older individuals have a recovery rate that is comparable with younger adults, they often take longer to recover, have more frequent relapses, and are more sensitive to the side effects of the drugs.

CLINICAL IMPLICATIONS

Individuals undergoing treatment for LLD and those whose illness has not been diagnosed or treated often are seen with significant oral disease by the dentist. Dentists need to be cognizant of how to safely and compassionately provide care to those already receiving mental health services. They must also be familiar with the psychiatric symptoms of the disorder to effectuate a timely referral to a physician of those with occult or relapsing disease. LLD is frequently associated with a disinterest in oral hygiene, a cariogenic diet, diminished salivary flow, rampant dental decay, advanced periodontal disease, and oral dysesthesias. Many medications used to treat the disease magnify the xerostomia and increase the incidence of dental disease. Appropriate dental management necessitates a vigorous preventive dental education program, the use of artificial salivary products, antiseptic mouthwash, daily fluoride mouth rinse, and special precautions in administration of local anesthetics with vasoconstrictors and prescription of analgesics.

CONCLUSION

Dentists who invoke appropriate precautions can usually provide a full range of services to individuals with LLD, thereby enhancing patient self-esteem and contributing to the psychotherapeutic aspect of management.

Cerebral haemodynamics and depression in the elderly

BACKGROUND

Evidence from epidemiological and neuroimaging studies suggests that cerebrovascular disease is associated with depressive disorders in the elderly, but the extent to which it contributes to the pathogenesis of late life depression is unclear.

OBJECTIVE

To investigate the relation between cerebral haemodynamics and depression in a population based study, using transcranial Doppler ultrasonography.

METHODS

Cerebral blood flow velocity and CO2 induced vasomotor reactivity in the middle cerebral artery were measured in 2093 men and women who participated in the Rotterdam study. All subjects were screened for depressive symptoms using the Center of Epidemiological Studies Depression scale, and those with a score of 16 or over had a psychiatric work up. In a semistructured interview, diagnoses of depressive disorders according to the DSM-IV and subthreshold depressive disorder were established. Analyses of covariance controlled for age, sex, stroke, cognitive score, and cardiovascular risk factors were used to compare means of haemodynamic variables.

RESULTS

Subjects with depressive symptoms had reduced blood flow velocities (mean difference, -2.9 cm/s; 95% confidence interval (CI), -5.0 to -0.8; p = 0.008) and lower vasomotor reactivity (mean difference -0.5%/kPa; 95% CI, -1.0 to -0.05; p = 0.03). Blood flow velocity was reduced most in subjects suffering from a DSM-IV depressive disorder (mean difference, -4.9 cm/s; 95% CI, -8.5 to -1.4; p = 0.006). The overall reduction in vasomotor reactivity was accounted for by subjects with subthreshold depressive disorder.

CONCLUSIONS

Depression in late life is associated with cerebral haemodynamic changes that can be assessed by transcranial Doppler ultrasonography. The observed reduction in cerebral blood flow velocity could be a result of reduced demand in more seriously depressed cases with a DSM-IV disorder, whereas reduced CO2 induced cerebral vasomotor reactivity is a possible causal factor for subthreshold depressive disorder.

Effects of medications on cerebral blood flow in late-life depression

Both normal aging and late-life depression (LLD) are associated with reductions in regional cerebral blood flow (rCBF). The impact of medication treatment in baseline rCBF abnormalities in LLD is being investigated via functional imaging research. Some of this work can be informed by pharmacologic challenge studies, which exploit the role of serotonin in regulating rCBF. Preliminary evidence suggests that there may be both state- and trait-level disturbances in rCBF in LLD, and that a common pathway towards clinical response to somatic antidepressant treatments involves reduction in rCBF in critical prefrontal cortical brain regions. Studies of the effects of medications on rCBF in LLD have implications for understanding the neurobiology of treatment resistance in the elderly as well as the mechanisms of action of antidepressant treatments.

Serotonin, cerebral blood flow, and cerebral metabolic rate in geriatric major depression and normal aging

While there is substantial evidence for abnormalities in serotonin (5-HT) neurotransmission in major depressive disorder (MDD), almost all of the findings derive from studies of young adults. Moreover, relatively little research has assessed brain 5-HT transmission in vivo. Neuroendocrine studies do not permit evaluation of a range of brain regions, but only the limited circuitry associated with hormone release. Data from autopsy studies are limited by the difficulties of assessment of the acute clinical picture before death, and by post-mortem artifacts. In vivo neuroimaging techniques overcome many of the methodological limitations of both these approaches. There is a large body of imaging data indicating regional cerebral blood flow (rCBF) and cerebral metabolic rate (rCMR) decrements both with aging and in patients with MDD. While the physiological bases for these phenomena are largely unknown, changes in brain 5-HT function may be involved. Neuroanatomical studies have revealed an intricate network of 5-HT-containing neurons within the cerebral microvasculature, with physiological evidence for serotonergic control of both rCBF and rCMR. Acute pharmacological challenges are available to probe brain 5-HT function. Such paradigms, using neuroendocrine responses as endpoints, have been of some utility in predicting outcome with antidepressant treatment. The role of 5-HT dysregulation in geriatric MDD takes on more importance given concerns regarding putative reduced efficacy of serotonin-specific reuptake inhibitors (SSRIs) in this population. If this is due to diminished responsivity of 5-HT systems, then the ability to identify antidepressant nonresponders via 5-HT challenge in combination with neuroimaging measures may have important clinical utility.