Structural neuroimaging research methods in geriatric depression

Activation of WNT and CREB signaling pathways in human neuronal cells in response to the Omega-3 fatty acid docosahexaenoic acid (DHA)

A subset of individuals with major depressive disorder (MDD) elects treatment with complementary and alternative medicines (CAMs), including the omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Previous studies in rodents suggest that DHA modulates neurodevelopmental processes, including adult neurogenesis and neuroplasticity, but the molecular and cellular mechanisms of DHA's potential therapeutic effect in the context of human neurobiology have not been well established. Here we sought to address this knowledge gap by investigating the effects of DHA using human iPSC-derived neural progenitor cells (NPCs) and post-mitotic neurons using pathway-selective reporter genes, multiplexed mRNA expression profiling, and a panel of metabolism-based viability assays. Finally, real-time, live-cell imaging was employed to monitor neurite outgrowth upon DHA treatment. Overall, these studies showed that DHA treatment (0-50 μM) significantly upregulated both WNT and CREB signaling pathways in human neuronal cells in a dose-dependent manner with 2- to 3-fold increases in pathway activation. Additionally, we observed that DHA treatment enhanced survival of iPSC-derived NPCs and differentiation of post-mitotic neurons with live-cell imaging, revealing increased neurite outgrowth with DHA treatment within 24 h. Taken together, this study provides evidence that DHA treatment activates critical pathways regulating neuroplasticity, which may contribute to enhanced neuronal cell viability and neuronal connectivity. The extent to which these pathways represent molecular mechanisms underlying the potential beneficial effects of omega-3 fatty acids in MDD and other brain disorders merits further investigation.

A specific pattern of gray matter atrophy in Alzheimer's disease with depression

Considering the high incidence of depressive symptoms in Alzheimer's disease (AD), we conducted a large-sample study to investigate the pattern of gray matter (GM) abnormalities that differentiates depressive from non-depressive AD patients. We included 201 AD patients who underwent MRI assessment and categorized them into depressive and non-depressive subgroups based on the Geriatric Depression Scale (GDS; cut-off score: ≤9). We performed whole-brain voxel-based morphometry analysis in 173 patients after MRI quality control and used between-group comparisons and regression analysis models to analyze the volumetric data controlling for nuisance variables. Depressive AD patients had extensive GM volume loss mainly in the paracentral region, specifically in post- and pre-central gyrus, supplementary motor areas and thalamus compared to non-depressive patients. Similar findings were obtained for the group of 173 patients using regression analysis and GDS score as predictor variable. We provided the first clear demonstration of a unique pattern of GM atrophy that characterizes AD patients with depression which is consistent with regions implicated in the phenomenon of psychomotor retardation that characterizes depression.

Effects of white matter integrity and brain volumes on late life depression in the Framingham Heart Study

BACKGROUND

It is unclear whether brain white matter hyperintensities (WMHI) causes or is a result of late life depression. We used the Framingham Heart Study offspring to examine whether indices of brain aging are related to incident depression in the elderly.

METHODS

The Center for Epidemiologic Studies Depression Scale (CES-D) was administered along with a brain MRI scan at baseline and was re-administered (n = 1212) at an average 6.6 + 0.6 year follow-up. The outcomes (i) change in CES-D scores from baseline; (ii) depression defined as CES-D ≥16; (iii) severe depression defined as CES-D ≥21; and (iv) CES-D cutoff scores and/or on antidepressant were used.

RESULTS

Among those who did not have depression at baseline, 9.1% (n = 110) developed depression, 4.0% (n = 48) developed severe depressive symptoms, and 11.1% (n = 135) were put on antidepressants. When depressive symptoms only was the outcome, we found that baseline WMHI was positively associated with change in CES-D scores and that those with an extensive WMHI at baseline had a high risk of developing severe depressive symptoms; the relationship was strengthened in the absence of cardiovascular diseases. In contrast, when depressive symptoms or taking antidepressant was the outcome, larger total cerebral brain volume and temporal lobe brain volume, but not WMHI, were negatively associated with the development of depression.

CONCLUSIONS

Brain WMHI is a probable risk factor for vascular depression in the elderly. The depression outcomes with and without antidepressant were related to different brain pathologies. Copyright © 2016 John Wiley & Sons, Ltd.

Structural imaging in late-life depression: association with mood and cognitive responses to antidepressant treatment

OBJECTIVES

Recent positron emission tomography studies of cerebral glucose metabolism have identified the functional neural circuitry associated with mood and cognitive responses to antidepressant treatment in late life depression (LLD). The structural alterations in these networks are not well understood. The present study used magnetic resonance (MR) imaging and voxel-based morphometry to evaluate the association between gray matter volumes and changes in mood symptoms and cognitive function with treatment with the antidepressant citalopram.

DESIGN

Open-label trial with baseline brain MR scan. Mood and cognitive assessments performed at baseline and during citalopram treatment.

SETTING

Outpatient clinics of an academic medical center.

PARTICIPANTS

17 previously unmedicated patients age 55 years or older with a major depressive episode and 17 non-depressed comparison subjects.

INTERVENTION

12-week trial of flexibly dosed citalopram.

MEASUREMENTS

Gray matter volumes, Hamilton Depression Rating Scale, California Verbal Learning Test, Delis-Kaplan Executive Function System.

RESULTS

In LLD, higher gray matter volumes in the cingulate gyrus, superior and middle frontal gyri, middle temporal gyrus, and precuneus was associated with greater mood improvement. Higher gray matter volumes in primarily frontal areas were associated with greater improvement in verbal memory and verbal fluency performance.

CONCLUSIONS

Associations with antidepressant induced improvements in mood and cognition were observed in several brain regions previously correlated with normalization of glucose metabolism after citalopram treatment in LLD. Future studies will investigate molecular mechanisms underlying these associations (e.g., beta-amyloid, inflammation, glutamate).

Graph theory analysis of cortical-subcortical networks in late-life depression

OBJECTIVES

Late-life major depression (LLD) is characterized by distinct epidemiologic and psychosocial factors, as well as medical comorbidities that are associated with specific neuroanatomical differences. The purpose of this study was to use interregional correlations of cortical and subcortical volumes to examine cortical-subcortical structural network properties in subjects with LLD compared with healthy comparison subjects.

METHODS

This was a cross-sectional neuroimaging study conducted in the general community. We recruited 73 healthy elderly comparison subjects and 53 subjects with LLD who volunteered in response to advertisements. Brain network connectivity measures were generated by correlating regional volumes after controlling for age, gender, and intracranial volume by using the Brain Connectivity Toolbox.

RESULTS

Results for overall network strength revealed that LLD networks showed a greater magnitude of associations for both positive and negative correlation weights compared with healthy elderly networks. LLD networks also demonstrated alterations in brain network structure compared with healthy comparison subjects. LLD networks were also more vulnerable to targeted attacks compared with healthy elderly comparison subjects, and this vulnerability was attenuated when controlling for white matter alterations.

CONCLUSIONS

Overall, this study demonstrates that cortical-subcortical network properties are altered in LLD and may reflect the underlying neuroanatomical vulnerabilities of the disorder.

Involvement of brain-derived neurotrophic factor in late-life depression

Brain-derived neurotrophic factor (BDNF), one of the major neurotrophic factors, plays an important role in the maintenance and survival of neurons, synaptic integrity, and synaptic plasticity. Evidence suggests that BDNF is involved in major depression, such that the level of BDNF is decreased in depressed patients and that antidepressants reverse this decrease. Stress, a major factor in depression, also modulates BDNF expression. These studies have led to the proposal of the neurotrophin hypothesis of depression. Late-life depression is associated with disturbances in structural and neural plasticity as well as impairments in cognitive behavior. Stress and aging also play a crucial role in late-life depression. Many recent studies have suggested that not only expression of BDNF is decreased in the serum/plasma of patients with late-life depression, but structural abnormalities in the brain of these patients may be associated with a polymorphism in the BDNF gene, and that there is a relationship between a BDNF polymorphism and antidepressant remission rates. This review provides a critical review of the involvement of BDNF in major depression, in general, and in late-life depression, in particular.

Structural brain abnormalities in women with subclinical depression, as revealed by voxel-based morphometry and diffusion tensor imaging

BACKGROUND

Brain structural changes accompany major depressive disorder, but whether subclinical depression is accompanied by similar changes in brain volume and white matter integrity is unknown. By using voxel-based morphometry (VBM) of the gray matter and tract-specific analysis based on diffusion tensor imaging (DTI) of the white matter, we explored the extent to which abnormalities could be identified in specific brain structures of healthy adults with subclinical depression.

METHODS

The subjects were 21 community-dwelling adults with subclinical depression, as measured by their Center for Epidemiologic Studies Depression Scale (CES-D) scores. They were not demented and had no neurological or psychiatric history. We collected brain magnetic resonance images of the patients and of 21 matched control subjects, and we used VBM to analyze the differences in regional gray matter volume between the two groups. Moreover, we examined the white matter integrity by using tract-specific analysis based on the gray matter volume changes revealed by VBM.

RESULTS

VBM revealed that the volumes of both anterior cingulate gyri and the right rectal gyrus were smaller in subclinically depressed women than in control women. Calculation of DTI measures in the anterior cingulum bundle revealed a positive correlation between CES-D scale score and radial diffusivity in the right anterior cingulum in subclinically depressed women.

LIMITATIONS

The small sample size limits the stability of the reported findings.

CONCLUSIONS

Gray matter volume reduction and white matter integrity change in specific frontal brain regions may be associated with depressive symptoms in women, even at a subclinical level.

Structural neuroimaging of geriatric depression

There is a large literature on the neuroanatomy of late-life depression that continues to grow with the discovery of novel structural imaging techniques along with innovative methods to analyze the images. Such advances have helped identify specific areas, characteristic lesions, and changes in the chemical composition in these regions that might be important in the pathophysiology of this complex disease. This article reviews relevant findings by each structural neuroimaging technique. When validated across many studies, such findings can serve as neuroanatomic markers that can help generate rational hypotheses for future studies to further understanding of geriatric depression.

Longitudinal MR study of brain structure and hippocampus volume in major depressive disorder

OBJECTIVE

To determine whether long-term course of treated major depression has an effect on the structure of the brain and the hippocampal volume.

METHOD

An 11-year follow-up procedure was used with data collection at baseline and again at follow-up. Tensor-based morphometry (TBM) and automatic hippocampal volume measure was performed on different datasets. The baseline dataset consisted of T1-weighted magnetic resonance images (MRIs) of 24 in-patients suffering from major depression and 33 healthy controls. The second dataset consisted of T1-weighted MRIs of 31 remitted depressive patients and 36 healthy controls. The longitudinal dataset consisted of 19 patients and 19 matched healthy controls present at both the first and the second dataset. Brain segmentation and hippocampal segmentation were fully automated and were based on a spatial normalization to the International Consortium of Brain Mapping (ICBM) non-linear model.

RESULTS

Depressed patients were found to have smaller temporal lobes bilaterally, medulla and right hippocampus at baseline. However, these changes were not found at follow-up 11 years later. Moreover, these changes did not significantly correlate with the illness outcome.

CONCLUSION

Brain structure changes seem to be state dependent in major depression, only occurring in acute episode of major depression and normalizing after remission.

The prefrontal-limbic network in depression: Modulation by hypothalamus, basal ganglia and midbrain

The anterior cingulate cortex, amygdala and hippocampus form part of an interconnected prefrontal neocortical and limbic archicortical network that is dysregulated in major depressive disorders (MDD). Modulation of this prefrontal-limbic network (PLN) is principally through the hypothalamus, basal ganglia and midbrain. Here the likely mechanisms by which these modulations are affected are described and the implications of their failure for depression associated with suicidal diathesis, late-life and psychoses discussed.

Vascular function in older adults with depressive disorder

BACKGROUND

Cerebrovascular disease plays an important role in depressive disorder, especially in older adults. An understanding of vascular function in depression is important etiologically and to develop innovative treatments that may improve prognosis by ameliorating vascular damage.

METHODS

This study assessed endothelial function, arterial stiffness, and atherosclerosis in a variety of vessel beds in 25 elderly subjects with depressive disorder compared with 21 nondepressed control subjects. Subjects underwent pulse wave velocity, pulse wave analysis, carotid intima media thickness analysis, and magnetic resonance imaging. A subset (16 patients and 15 control subjects) had assessment of biopsied small artery dilatation to acetylcholine to further assess endothelial function.

RESULTS

The mean sample age was 72.4 years with an average age at onset for depression of 60 years. Mean carotid intima media thickness was significantly higher in depressed subjects (p < .01). Pulse wave velocity was 1.6 m/sec higher in depressed subjects (borderline significance). There was a significant reduction in the dilatation response to acetylcholine in preconstricted small arteries (p = .01). On magnetic resonance imaging, depressed subjects had significantly more dilated Virchow-Robin spaces in the basal ganglia (p = .01). Depressed subjects had greater volume of white matter lesions in all regions, but this did not reach statistical significance. There were no baseline differences in vascular risk.

CONCLUSIONS

Depression in the elderly is associated with poorer endothelial function and more atherosclerosis. This is associated with a greater white matter hyperintensities lesion load and basal ganglia microangiopathy. The use of vasoprotective drugs to improve endothelial function or retard atherosclerosis as depression-modifying agents should be explored.

ROBERTE. Research advances in geriatric depression

Technical advances have facilitated the exploration of factors related to geriatric depression and have helped generate novel biological and psychosocial treatment approaches. This review summarizes the main advancements in epidemiology, clinical presentation and course, genetics, and other areas of biological research. Treatment interventions outlined in this paper include electroconvulsive therapy, repetitive transcranial magnetic stimulation, magnetic seizure therapy, vagus nerve stimulation, deep brain stimulatn, depression prophylaxis, multidisciplinary approaches to depression treatment, and psychotherapy. Forms of psychotherapy for geriatric depression summarized include interpersonal psychotherapy, supportive psychotherapy, cognitive-behavioral therapy, problem-solving therapy, and ecosystem-focused therapy. Neuroimaging techniques based on magnetic resonance imaging are discussed briefly, including volumetric brain studies, diffusion tensor imaging, fractional anisotropy, fiber tractography, magnetization transfer imaging, and blood-oxygenation-level-dependent functional magnetic resonance imaging. Finally, treatment effectiveness is addressed in a discussion of new models to improve access to and quality of care offered in the community.

31Phosphorus magnetic resonance spectroscopy study of tissue specific changes in high energy phosphates before and after sertraline treatment of geriatric depression

INTRODUCTION

We investigated tissue specific differences in markers of energy metabolism, including high energy phosphate compounds (beta and total NTP, PCr) and pH, in older adults with depression compared with healthy controls, before and after a 12-week treatment trial of sertraline.

METHODS

Thirteen older adults, age > or =55, with Major Depressive Disorder (HAMD(17) score of > or =18) were recruited along with ten age-matched controls. The depression subjects had a pre- and post-treatment 4T (31)P-MRS scan using a three-dimensional chemical shift imaging sequence. The extracted brain images were segmented into white matter (WM), gray matter (GM) and CSF. A linear mixed effects model analyzed the effects of pre-treatment and post-treatment depression on phosphorus metabolite concentration estimates (including calculated pH and Mg(++)).

RESULTS

Total tissue beta-NTP (-8%, t(18.66) = 3.50; p = 0.0024) and total tissue total NTP (-6%, t(17.41) = 2.68; p = 0.0156) were lower in subjects with geriatric depression compared with healthy controls. Total tissue levels of total-NTP changed significantly with treatment (-2%, t(14.84) = -2.47; p = 0.0259). Total NTP was reduced in the WM, but not the GM, in the pre-treatment depression group (t(51.65) = 4.02; p = 0.0002). Intracellular pH was higher in the GM of subjects with pre-treatment depression (t(1133.84) = -2.10; p = 0.0353) and decreased to approximate control levels after treatment (t(648.86) = -2.53; p = 0.0115).

DISCUSSION

These findings demonstrate bioenergetic changes including tissue specific differences in (31)P-MRS metabolites in geriatric depression. Decreased white matter total NTP may reflect alterations in white matter function.

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.

Hypertension as a risk factor for developing depressive symptoms among community-dwelling elders

OBJECTIVE

To determine whether hypertension (HTA) is an independent predictor of depressive symptoms (DS) in a sample of elderly Mexican community-dwelling persons.

MATERIAL AND METHODS

Two-year longitudinal study of 3,276 community-dwelling persons aged 60 years and older, participating in the Mexican Health and Aging Study. Subjects that self-reported both having or not having HTA while denying DS at baseline were included. Two-year follow-up data were analyzed, and multiple regression analyses were used to test whether HTA is an independent predictor of incident DS after adjusting for many potential confounders.

RESULTS

Mean age of participants was 68.4 +/- 6.9 years. Prevalence of HTA was 36.6%. At follow-up, 28.7% developed DS. After adjusting for multiple covariates (age, sex, education level, relationship status, self-reported health and economic status, diabetes, arthritis, stroke, ischemic cardiopathy, falls, pain, hearing impairment, visual impairment, urinary incontinence, cognitive impairment, smoking, alcohol use, and baseline disability), HTA was an independent predictor of DS at two years followup (Adjusted Odds Ratio = 1.18; 95% confidence interval = 1.01-1.40).

CONCLUSIONS

Hypertension is an independent risk factor for the development of depressive symptoms. Programs to support early treatment of cardiovascular disease and hypertension should be implemented in order to prevent late-onset of depressive symptoms.

Three-dimensional surface mapping of the caudate nucleus in late-life depression

OBJECTIVE

To compare the volumes of the caudate nucleus, using traditional volumetry and a three-dimensional brain mapping technique, in a group of individuals with late-life depression and a group of age- and education-equated nondepressed comparison subjects.

DESIGN

Cross-sectional.

SETTING

University Medical Center.

PARTICIPANTS

Twenty-three nondemented subjects with late-life depression and 15 age- and education-equated elderly comparison subjects (depressed mean years of age: 70.5 +/- 5.7 SD, comparison subjects = 69.9 years +/- 6.4) with no history of psychiatric or neurologic disease.

MEASUREMENTS

Structural magnetic resonance imaging. Three-dimensional (3-D) surface models were created from manually traced outlines of the caudate nucleus from spoiled gradient echo images. Models were geometrically averaged across subjects and statistical maps created to localize any regional volume differences between groups.

RESULTS

Relative to comparison subjects, depressed subjects had significantly lower mean volumes for both the left (p = 0.029) and right (p = 0.052) caudate nucleus as well as total caudate volume (p = 0.032). Total volumes were 13.1% less in the depressed group (13.5% on the left and 12.6% on the right). 3-D maps further localized these reductions to the caudate head. Volume reductions were correlated with depression severity, as measured by the 17-item Hamilton Depression Rating Scale.

CONCLUSION

Late-life depression is associated with left and right caudate nucleus reduction especially in anterior portions. Among depressed subjects, greater caudate reduction was associated with more severe depression. These results are consistent with growing evidence that the anterior caudate nucleus, especially the head, may be structurally and functionally abnormal in affective disorders.

Pattern of brain atrophy in elderly patients with depression revealed by voxel-based morphometry

In this study, we explored to what extent brain abnormalities can be identified in specific brain structures of patients suffering from late onset depression. We examined the structural difference in regional gray and white matter volume between 14 community-dwelling patients suffering from geriatric depression and 20 age-matched non-depressed normal subjects by voxel-based morphometry (VBM) based on magnetic resonance imaging. All subjects also underwent an extensive neuropsychological assessment. Compared with control subjects, patients with depression were impaired in measures of verbal and visual memory, construction, executive ability, and information-processing speed. VBM of gray matter revealed a significant decrease of volume in the right rostral hippocampus, in the right amygdala and in the medial orbito-frontal cortex (gyrus rectus) bilaterally. In the correlation analysis of gray matter volume with the score of the geriatric depression scale, we observed a negative correlation with the medial orbito-frontal cortex (gyrus rectus) bilaterally. There were no differences in white matter volumes between patients with depression and healthy control subjects. The most important limitation of this study was sample size. A larger sample size may have improved detection of changes not reaching significance. Furthermore, our results may not be generalizable across depression severity or to hospitalized patients. The findings are consistent with our hypothesis that depression in the elderly is associated with local gray matter dysfunction.

Executive dysfunction in elderly bipolar manic patients

OBJECTIVE

This study used neuropsychological measures of executive skills to examine the functioning of frontostriatal networks in elderly bipolar patients.

DESIGN

The authors hypothesized that elders with bipolar mania would exhibit poor executive functions relative to both elderly comparison subjects and depressed patients.

SETTING

The study was conducted in the geriatric psychiatry services of a university hospital.

PARTICIPANTS

Nondemented elders: 14 with bipolar disorder I, manic (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition), 14 with unipolar major depression (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition), and 14 nonpsychiatric comparison (NC) subjects.

MEASUREMENTS

Executive functions were assessed with the initiation/perseveration subscale of the Dementia Rating Scale and the manual Go/No-Go tasks from the extended initiation/perseveration scale.

RESULTS

Manic elders demonstrated poor performance on tasks of initiation/perseveration and response inhibition, and performed significantly worse than both depressed patients and NC subjects. In this sample, there was no evidence for a relationship between severity of manic symptoms and executive performance.

CONCLUSION

These findings extend the observation that elderly bipolar manic patients have deficits in executive functioning compared with NC samples and provide evidence that the executive deficits demonstrated by bipolar manic elders can be more severe than those in unipolar depressed elders. As executive functions require frontostriatal integrity, these observations support investigation of specific frontostriatal network abnormalities in late-life bipolar disorder.