Beta-amyloid deposition and cognitive function in patients with major depressive disorder with different subtypes of mild cognitive impairment: (18)F-florbetapir (AV-45/Amyvid) PET study

Amyloid deposition and its association with depressive symptoms and cognitive functions in late-life depression: a longitudinal study using amyloid-β PET images and neuropsychological measurements

BACKGROUND

Although depression is linked to an increased risk of dementia, the association between late-onset depression (LOD) and amyloid burden remains unclear. This study aimed to determine amyloid deposition in patients with LOD compared to healthy controls (HC) using amyloid-beta (Aβ) positron emission tomography (PET) images and neuropsychological assessments.

METHODS

Forty patients first diagnosed with major depressive disorder after the age of 60 (LOD) and twenty-one healthy volunteers (HC) were enrolled. Depression and anxiety were evaluated using the 17-item Hamilton Depression Scale, Hamilton Anxiety Rating Scale, and Clinical Global Impression Scale. Cognitive function was assessed using the Korean versions of the Mini-Mental Status Examination, Montreal Cognitive Assessment, and Seoul Neuropsychological Screening Battery at baseline and 3-month follow-up. 18F-florbetapir PET images were co-registered with T1-weighted magnetic resonance images.

RESULTS

There was no significant difference in Aβ deposition between LOD and HC groups. No significant correlation between Aβ burden and depressive symptom severity was found in LOD patients. Higher somatic anxiety was correlated with lower Aβ burden in multiple brain regions, including the left inferior frontal lobe (p = 0.009), right anterior cingulate (p = 0.003), and right superior frontal lobe (p = 0.009). Despite cognitive recovery in areas such as attention (Digit Span Forward, p = 0.026), memory (Auditory Verbal Learning Test Recall Total, p = 0.010; Rey Complex Figure Test Delayed Recall, p = 0.039), and frontal executive function (Contrasting Program, p = 0.033) after three months of antidepressant treatment, cognitive improvement showed no association with amyloid deposition.

CONCLUSIONS

These findings suggest distinct mechanisms may underlie amyloid deposition in neurodegenerative changes associated with depression. While amyloid burden in specific brain regions negatively correlated with somatic anxiety, it showed no significant correlation with the severity of depression or overall cognitive function.

Novel insight into astrocyte-mediated gliotransmission modulates the synaptic plasticity in major depressive disorder

Major depressive disorder (MDD) is a form of glial cell-based synaptic dysfunction disease in which glial cells interact closely with neuronal synapses and perform synaptic information processing. Glial cells, particularly astrocytes, are active components of the brain and are responsible for synaptic activity through the release gliotransmitters. A reduced density of astrocytes and astrocyte dysfunction have both been identified the brains of patients with MDD. Furthermore, gliotransmission, i.e., active information transfer mediated by gliotransmitters between astrocytes and neurons, is thought to be involved in the pathogenesis of MDD. However, the mechanism by which astrocyte-mediated gliotransmission contributes to depression remains unknown. This review therefore summarizes the alterations in astrocytes in MDD, including astrocyte marker, connexin 43 (Cx43) expression, Cx43 gap junctions, and Cx43 hemichannels, and describes the regulatory mechanisms of astrocytes involved in synaptic plasticity. Additionally, we investigate the mechanisms acting of the glutamatergic, gamma-aminobutyric acidergic, and purinergic systems that modulate synaptic function and the antidepressant mechanisms of the related receptor antagonists. Further, we summarize the roles of glutamate, gamma-aminobutyric acid, d-serine, and adenosine triphosphate in depression, providing a basis for the identification of diagnostic and therapeutic targets for MDD.

Seeing beyond the symptoms: biomarkers and brain regions linked to cognitive decline in Alzheimer's disease

Objective

Early Alzheimer's disease (AD) diagnosis remains challenging, necessitating specific biomarkers for timely detection. This study aimed to identify such biomarkers and explore their associations with cognitive decline.

Methods

A cohort of 1759 individuals across cognitive aging stages, including healthy controls (HC), mild cognitive impairment (MCI), and AD, was examined. Utilizing nine biomarkers from structural MRI (sMRI), diffusion tensor imaging (DTI), and positron emission tomography (PET), predictions were made for Mini-Mental State Examination (MMSE), Clinical Dementia Rating Scale Sum of Boxes (CDRSB), and Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS). Biomarkers included four sMRI (e.g., average thickness [ATH]), four DTI (e.g., mean diffusivity [MD]), and one PET Amyloid-β (Aβ) measure. Ensemble regression tree (ERT) technique with bagging and random forest approaches were applied in four groups (HC/MCI, HC/AD, MCI/AD, and HC/MCI/AD).

Results

Aβ emerged as a robust predictor of cognitive scores, particularly in late-stage AD. Volumetric measures, notably ATH, consistently correlated with cognitive scores across early and late disease stages. Additionally, ADAS demonstrated links to various neuroimaging biomarkers in all subject groups, highlighting its efficacy in monitoring brain changes throughout disease progression. ERT identified key brain regions associated with cognitive scores, such as the right transverse temporal region for Aβ, left and right entorhinal cortex, left inferior temporal gyrus, and left middle temporal gyrus for ATH, and the left uncinate fasciculus for MD.

Conclusion

This study underscores the importance of an interdisciplinary approach in understanding AD mechanisms, offering potential contributions to early biomarker development.

Cluster analysis dissecting cognitive deficits in older adults with major depressive disorder and the association with neurofilament light chain

BACKGROUND

Cognitive impairment is a growing problem with increasing burden in global aging. Older adults with major depressive disorder (MDD) have higher risk of dementia. Neurofilament light chain (NfL) has been proven as a potential biomarker in neurodegenerative disease, including dementia. We aimed to investigate the association between cognitive deficits and NfL levels in older adults with MDD.

METHODS

In this cross-sectional study, we enrolled 39 MDD patients and 15 individuals with mild neurocognitive disorder or major neurocognitive disorder, Alzheimer's type, as controls, from a tertiary psychiatric hospital. Both groups were over age 65 and with matched Mini-Mental State Examination (MMSE) score. Demographic data, clinical variables, and plasma NfL levels were obtained. We used cluster analysis according to their cognitive profile and estimated the correlation between plasma NfL levels and each cognitive domain.

RESULTS

In the MDD group, participants had higher rate of family psychiatry history and current alcohol use habit compared with controls. Control group of neurocognitive disorders showed significantly lower score in total MMSE and higher plasma NfL levels. Part of the MDD patients presented cognitive deficits clustered with that of neurocognitive disorders (cluster A). In cluster A, the total MMSE score (r=-0.58277, p=0.0287) and the comprehension domain (r=-0.71717, p=0.0039) were negatively correlated to NfL levels after adjusting for age, while the associations had not been observed in the other cluster.

CONCLUSIONS

We noted the negative correlation between NfL levels and cognition in MDD patients clustered with neurodegenerative disorder, Alzheimer's type. NfL could be a promising candidate as a biomarker to predict subtype of patients in MDD to develop cognitive decline. Further longitudinal studies and within MDD cluster analysis are required to validate our findings for clinical implications.

Biological factors influencing depression in later life: role of aging processes and treatment implications

Late-life depression occurring in older adults is common, recurrent, and malignant. It is characterized by affective symptoms, but also cognitive decline, medical comorbidity, and physical disability. This behavioral and cognitive presentation results from altered function of discrete functional brain networks and circuits. A wide range of factors across the lifespan contributes to fragility and vulnerability of those networks to dysfunction. In many cases, these factors occur earlier in life and contribute to adolescent or earlier adulthood depressive episodes, where the onset was related to adverse childhood events, maladaptive personality traits, reproductive events, or other factors. Other individuals exhibit a later-life onset characterized by medical comorbidity, pro-inflammatory processes, cerebrovascular disease, or developing neurodegenerative processes. These later-life processes may not only lead to vulnerability to the affective symptoms, but also contribute to the comorbid cognitive and physical symptoms. Importantly, repeated depressive episodes themselves may accelerate the aging process by shifting allostatic processes to dysfunctional states and increasing allostatic load through the hypothalamic-pituitary-adrenal axis and inflammatory processes. Over time, this may accelerate the path of biological aging, leading to greater brain atrophy, cognitive decline, and the development of physical decline and frailty. It is unclear whether successful treatment of depression and avoidance of recurrent episodes would shift biological aging processes back towards a more normative trajectory. However, current antidepressant treatments exhibit good efficacy for older adults, including pharmacotherapy, neuromodulation, and psychotherapy, with recent work in these areas providing new guidance on optimal treatment approaches. Moreover, there is a host of nonpharmacological treatment approaches being examined that take advantage of resiliency factors and decrease vulnerability to depression. Thus, while late-life depression is a recurrent yet highly heterogeneous disorder, better phenotypic characterization provides opportunities to better utilize a range of nonspecific and targeted interventions that can promote recovery, resilience, and maintenance of remission.

The shared molecular mechanisms underlying aging of the brain, major depressive disorder, and Alzheimer's disease: The role of circadian rhythm disturbances

An association with circadian clock function and pathophysiology of aging, major depressive disorder (MDD), and Alzheimer's disease (AD) is well established and has been proposed as a factor in the development of these diseases. Depression and changes in circadian rhythm have been increasingly suggested as the two primary overlapping and interpenetrating changes that occur with aging. The relationship between AD and depression in late life is not completely understood and probably is complex. Patients with major depression or AD suffer from disturbed sleep/wake cycles and altered rhythms in daily activities. Although classical monoaminergic hypotheses are traditionally proposed to explain the pathophysiology of MDD, several clinical and preclinical studies have reported a strong association between circadian rhythm and mood regulation. In addition, a large body of evidence supports an association between disruption of circadian rhythm and AD. Some clock genes are dysregulated in rodent models of depression. If aging, AD, and MDD share a common biological basis in pathophysiology, common therapeutic tools could be investigated for their prevention and treatment. Nitro-oxidative stress (NOS), for example, plays a fundamental role in aging, as well as in the pathogenesis of AD and MDD and is associated with circadian clock disturbances. Thus, development of therapeutic possibilities with these NOS-related conditions is advisable. This review describes recent findings that link disrupted circadian clocks to aging, MDD, and AD and summarizes the experimental evidence that supports connections between the circadian clock and molecular pathologic factors as shared common pathophysiological mechanisms underlying aging, AD, and MDD.

Decreased Cerebral Amyloid-β Depositions in Patients With a Lifetime History of Major Depression With Suspected Non-Alzheimer Pathophysiology

Cerebral amyloid-β (Aβ) depositions in depression in old age are controversial. A substantial proportion of individuals with late-life major depressive disorder (MDD) could be classified as having suspected non-Alzheimer’s disease pathophysiology (SNAP) by a negative test for the biomarker amyloid-β (Aβ−) but positive neurodegeneration (ND+). This study aimed to evaluate subthreshold Aβ loads in amyloid-negative MDD, particularly in SNAP MDD patients. This study included 46 amyloid-negative MDD patients: 23 SNAP (Aβ−/ND+) MDD and 23 Aβ−/ND− MDD, and 22 Aβ−/ND− control subjects. All subjects underwent ¹⁸F-florbetapir PET, FDG-PET, and MRI. Regions of interest (ROIs) and voxel-wise group comparisons were performed with adjustment for age, gender, and level of education. The SNAP MDD patients exhibited significantly deceased ¹⁸F-florbetapir uptakes in most cortical regions but not the parietal and precuneus cortex, as compared with the Aβ−/ND− MDD and control subjects (FDR correction, p < 0.05). No correlations of neuropsychological tests or depression characteristics with global cortical uptakes, but significant positive correlations between cognitive functions and adjusted hippocampal volumes among different groups were observed. The reduced Aβ depositions in the amyloid-negative MDD patients might be attributed mainly to the SNAP MDD patients. Our results indicated that meaningfully low amounts of subclinical Aβ might contain critical information on the non-amyloid-mediated pathogenesis.

Preventive Measures against the Development of Dementia in Old Age

Dementia is a neurological condition characterized by numerous types of central nervous system diseases, which gradually deteriorates an individual’s reasoning, rational thinking, and judgment abilities. As a serious public health concern that currently affects more than 50 million older adults, dementia is one of the most significant causes of incapacity, disability, and dependency among older adults. As new cases are expected to increase exponentially in the next three decades, dementia, which is not a normal feature of healthy aging despite the fact that it generally affects older adults disproportionately, requires enormous management and care efforts due to its associated socioeconomic, psychological, and physical burdens that involve the patient, their caregivers, guardians, family members, and society at large. Presently, there is no cure for dementia; however, this condition could be prevented. This narrative review aimed to provide a broad overview of studies detailing the alternative lifestyle modification-centered preventive measures against dementia. A comprehensive search of key databases to find articles related to this topic revealed that participating in regular physical activities, healthy eating and dieting, avoiding all forms of smoking, avoiding air pollutants, halting or reducing alcohol consumption, exercising the mind and being socially dynamic, getting enough rest and establishing good sleeping habits, infection prevention, stress prevention, avoidance of injuries, preventing the effects of social isolation and lockdowns, continuing education, and depression prevention are protective measures against the development of dementia.

Pathomechanisms of Vascular Depression in Older Adults

Depression in older individuals is a common complex mood disorder with high comorbidity of both psychiatric and physical diseases, associated with high disability, cognitive decline, and increased mortality The factors predicting the risk of late-life depression (LLD) are incompletely understood. The reciprocal relationship of depressive disorder and age- and disease-related processes has generated pathogenic hypotheses and provided various treatment options. The heterogeneity of depression complicates research into the underlying pathogenic cascade, and factors involved in LLD considerably differ from those involved in early life depression. Evidence suggests that a variety of vascular mechanisms, in particular cerebral small vessel disease, generalized microvascular, and endothelial dysfunction, as well as metabolic risk factors, including diabetes, and inflammation that may induce subcortical white and gray matter lesions by compromising fronto-limbic and other important neuronal networks, may contribute to the development of LLD. The "vascular depression" hypothesis postulates that cerebrovascular disease or vascular risk factors can predispose, precipitate, and perpetuate geriatric depression syndromes, based on their comorbidity with cerebrovascular lesions and the frequent development of depression after stroke. Vascular burden is associated with cognitive deficits and a specific form of LLD, vascular depression, which is marked by decreased white matter integrity, executive dysfunction, functional disability, and poorer response to antidepressive therapy than major depressive disorder without vascular risk factors. Other pathogenic factors of LLD, such as neurodegeneration or neuroimmune regulatory dysmechanisms, are briefly discussed. Treatment planning should consider a modest response of LLD to antidepressants, while vascular and metabolic factors may provide promising targets for its successful prevention and treatment. However, their effectiveness needs further investigation, and intervention studies are needed to assess which interventions are appropriate and effective in clinical practice.

Excess tau PET ligand retention in elderly patients with major depressive disorder

Depression is one of the common psychiatric disorders in old age. Major depressive disorder (MDD) has been identified as a risk factor or prodrome for neurodegenerative dementias, suggesting neuropathological overlaps and a continuum between MDD and neurodegenerative disorders. In this study, we examined tau and amyloid-β (Aβ) accumulations in the brains of MDD and healthy controls using positron emission tomography (PET) to explore pathological substrates of this illness. Twenty MDD and twenty age-matched, healthy controls were examined by PET with a tau radioligand, [¹¹C]PBB3, and an Aβ radioligand, [¹¹C]PiB. Radioligand retentions were quantified as a standardized uptake value ratio (SUVR). We also assessed clinical manifestations of the patients using the 17-item Hamilton Depression Scale, the Geriatric Depression Scale, and psychotic symptoms. Mean cortical [¹¹C]PBB3 SUVRs in MDD patients were significantly higher than those of healthy controls. These values were higher in MDD patients with psychotic symptoms than in those without any. The present findings indicate that tau depositions may underlie MDD, and especially in patients with psychotic symptoms. PET detection of tau accumulations may provide mechanistic insights into neuronal dysfunctions in these cases and could serve as predictions of their clinical consequences.

Different Sides of Depression in the Elderly: An In-depth View on the Role of Aβ Peptides

BACKGROUND

Late-onset depression (LOD) is the most common neuropsychiatric disorder associated with Alzheimer's disease (AD), often associated with structural and functional brain changes, neuropsychological impairments and negative family history for affective disorders. LOD could be a risk factor or a prodromal phase of AD; this has led to the investigation of the link between depression and amyloid-β (Aβ) peptides by measuring Aβ levels in plasma, cerebrospinal fluid (CSF) and brains of elderly depressed subjects.

OBJECTIVE

Clarify the complex relationship between depression, Aβ peptides and AD.

METHOD

We evaluated all articles published up to 2019 in PubMed in which Aβ was measured in serum (or plasma), CSF or brain in elderly with Major Depressive Disorder or depressive symptoms evaluated with standard scales.

RESULTS

Low plasma Aβ42 levels are strongly associated with depression severity. Plasma Aβ40 levels are higher in younger depressed, drug-resistant and those with more severe symptoms. CSF Aβ42 levels are lower in depressed than controls. PET-detected global and region-specific increases in Aβ deposition are sometimes associated with LOD, cognitive impairment, anxiety but not with Cardiovascular Diseases (CVDs)/CVD risk factors. Elderly depressed with CVDs/CVD risk factors have more frequently high plasma Aβ40 levels and drug-resistance; those without these co-morbidities have low plasma Aβ42 levels and a greater cognitive impairment.

CONCLUSION

Two specific Aβ profiles emerge in elderly depressed. One is associated with Aβ42 reductions in plasma and CSF, possibly reflecting increased brain amyloid deposition and prodromal AD. The other one is characterized by high plasma Aβ40 levels, cerebrovascular disease and clinically associated with increased AD risk.

Late-Life Depression Is Associated With Reduced Cortical Amyloid Burden: Findings From the Alzheimer's Disease Neuroimaging Initiative Depression Project

BACKGROUND

We evaluated the role of cortical amyloid deposition as a factor contributing to memory dysfunction and increased risk of dementia associated with late-life depression (LLD).

METHODS

A total of 119 older adult participants with a current diagnosis of major depression (LLD) from the Alzheimer's Disease Neuroimaging Initiative (ADNI) Depression Project study and 119 nondepressed (ND) cognitively unimpaired participants matched on age, sex, and APOE genotype were obtained from the ADNI database.

RESULTS

Thirty-three percent of LLD participants met ADNI criteria for mild cognitive impairment. Compared with ND individuals, the LLD group exhibited less global amyloid beta (Aβ) accumulation (p = .05). The proportion of amyloid positivity in the LLD group was 19.3% compared with 31.1% for the ND participants (p = .02). Among LLD participants, global Aβ was not associated with lifetime number of depressive episodes, lifetime length of depression, length of lifetime selective serotonin reuptake inhibitor use, or lifetime length of untreated depression (p > .21 for all). Global Aβ was associated with worse memory performance (p = .05). Similar results were found in secondary analyses restricting comparisons to the cognitively unimpaired LLD participants as well as when comparing the LLD group with an ND group that included participants with mild cognitive impairment.

CONCLUSIONS

Contrary to expectation, the LLD group showed less Aβ deposition than the ND group and Aβ deposition was not associated with depression history characteristics. Aβ was associated with memory, but this relationship did not differ between LLD and ND. Our results suggest that memory deficits and accelerated cognitive decline reported in previous studies of LLD are not due to greater cortical Aβ accumulation.

Glymphatic Dysfunction: A Bridge Between Sleep Disturbance and Mood Disorders

Mounting evidence demonstrates a close relationship between sleep disturbance and mood disorders, including major depression disorder (MDD) and bipolar disorder (BD). According to the classical two-process model of sleep regulation, circadian rhythms driven by the light-dark cycle, and sleep homeostasis modulated by the sleep-wake cycle are disrupted in mood disorders. However, the exact mechanism of interaction between sleep and mood disorders remains unclear. Recent discovery of the glymphatic system and its dynamic fluctuation with sleep provide a plausible explanation. The diurnal variation of the glymphatic circulation is dependent on the astrocytic activity and polarization of water channel protein aquaporin-4 (AQP4). Both animal and human studies have reported suppressed glymphatic transport, abnormal astrocytes, and depolarized AQP4 in mood disorders. In this study, the "glymphatic dysfunction" hypothesis which suggests that the dysfunctional glymphatic pathway serves as a bridge between sleep disturbance and mood disorders is proposed.

β-amyloid pathology is not associated with depression in a large community sample autopsy study

BACKGROUND

Depression has been associated with dementia. This study aimed to verify if β-amyloid Alzheimer's disease-type burden was associated with lifetime major depressive disorder (MDD) and with current depressive symptoms in a large population-based autopsy study.

METHODS

We included 1013 deceased subjects submitted to autopsy (mean age=74.3±11.6 years, 49% men) in a community sample. β-amyloid burden was measured in all cases based on the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) criteria for presence and density of neuritic plaques. Lifetime MDD was defined when at least one previous episode according to the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders - DSM (SCID). Depressive symptoms and cognitive impairment were determined using the depression item of the Neuropsychiatric Inventory (D-NPI>0) and the Clinical Dementia Rating scale (CDR>0.5) respectively.

RESULTS

Lifetime MDD, late life depression (LLD) and current depressive symptoms were associated with cognitive impairment (p<0.001). Additionally, neuritic plaques were associated with cognitive impairment (p<0.001). Moderate or frequent neurite plaque density was not associated with MDD, LLD or current depressive symptoms in multiple logistic models adjusted for age, gender, and cognitive impairment.

LIMITATIONS

In this cross-sectional study, all neuropsychiatric and cognitive assessment were based on informant-report of deceased participants.

CONCLUSIONS

Different clinical depictions of depression were associated with dementia in this large community sample of elderly individuals with multiethnic backgrounds. Notwithstanding, they were unrelated to β-amyloid pathology in the brain areas studied. The link between depression and dementia might be complex and determined by multiple factors.

Interactive effects of elevated homocysteine and late-life depression on cognitive impairment

BACKGROUND

Both an elevated homocysteine (Hcy) level and depression are risk factors for cognitive impairment in the general population, but no study has analyzed whether the coexistence of an elevated Hcy level and late-life depression (LLD) is associated with worse cognitive performance.

OBJECTIVE

We aimed to investigate the relationship between Hcy levels and cognitive function in individuals with LLD and whether the coexistence of an elevated Hcy level and LLD is associated with worse cognitive performance.

METHODS

A total of 113 LLD patients and 89 normal controls underwent a standardized clinical interview and comprehensive neuropsychological assessment battery. Plasma concentrations of Hcy were detected. Factorial analyses were performed to examine the impact of the coexistence of an elevated Hcy level and LLD on cognitive performance.

RESULTS

Plasma Hcy levels in patients with LLD were significantly higher than that in normal controls. Only for LLD patients, Hcy level was negatively correlated with global cognition, executive function, attention, and visual space. The factorial analysis showed that there was a significant interactive effect of Hcy level (normal and elevated levels) and LLD (with and without LLD) on global cognition. In post hoc comparisons, the elderly individuals with both elevated Hcy levels and LLD tended to have the worst global cognitive function compared with those with LLD or elevated Hcy levels alone.

CONCLUSIONS

The coexistence of an elevated Hcy level and LLD was associated with worse cognitive performance. Early intervention should be initiated to protect cognition in LLD patients with elevated Hcy levels.

Polyunsaturated fatty acid supplement alleviates depression-incident cognitive dysfunction by protecting the cerebrovascular and glymphatic systems

INTRODUCTION

Depression, the most prevalent mood disorder, has high comorbidity with cerebrovascular disease and cognitive decline. However, there is little understanding of the cellular mechanisms involved in depression and its comorbid cerebrovascular damage and cognition impairment. Here, we tested the prediction that the chronic unpredictable mild stress (CUMS) mouse model would manifest in disturbed glymphatic function and that dietary supplementation with polyunsaturated fatty acids (PUFA) could ameliorate these deficits while alleviating the depression-associated cognitive decline.

METHODS

To test the treatment effects of PUFA or Es on behaviours, we applied the tail suspension, open field, and sucrose preference tests to assess depressive symptoms, and applied the Morris water maze test to assess cognition in groups of control, chronic unpredictable mild stress (CUMS), PUFA, and escitalopram (Es) treatment. We measured the extracellular concentrations of dopamine (DA), 5-hydroxytryptamine (5-HT) and noradrenaline (NA) in microdialysates from prefrontal cortex (PFC) by liquid chromatography mass spectrometry. Glia cells and inflammatory factors were analysed with fluorescent immunochemistry and western blot, respectively. We tested brain vasomotor function with two-photon and laser speckle imaging in vivo, and measured glymphatic system function by two-photon imaging in vivo and fluorescence tracer imaging ex vivo, using awake and anesthetized mice. Besides, we monitored cortical spreading depression by laser speckle imaging system. AQP4 depolarization is analysed by fluorescent immunochemistry and western blot.

RESULTS

We confirmed that CUMS elicited depression-like and amnestic symptoms, accompanied by decreased monoamines neurotransmitter concentration in PFC and upregulated neuroinflammation markers. Moreover, CUMS mice showed reduced arterial pulsation and compliance in brain, and exhibited depolarized expression of AQP4, thus indicating glymphatic dysfunction both in awake and anesthetized states. PUFA supplementation rescued depression-like behaviours of CUMS mice, reduced neuroinflammation and cerebrovascular dysfunction, ultimately improved cognitive performance, all of which accompanied by restoring glymphatic system function. In contrast, Es treatment alleviated only the depression-like behavioural symptoms, while showing no effects on glymphatic function and depression-incident cognitive deficits.

CONCLUSIONS

The CUMS depression model entails suppression of the glymphatic system. PUFA supplementation rescued most behavioural signs of depression and the associated cognitive dysfunction by restoring the underlying glymphatic system disruption and protecting cerebral vascular function.

Tau PET With 18F-THK-5351 Taiwan Patients With Familial Alzheimer's Disease With the APP p.D678H Mutation

Background: Brain ¹⁸F-AV-45 amyloid positron emission tomography (PET) in Taiwanese patients with familial Alzheimer's disease with the amyloid precursor protein (APP) p.D678H mutation tends to involve occipital and cerebellar cortical areas. However, tau pathology in patients with this specific Taiwan mutation remains unknown. In this study, we aimed to study the Tau PET images in these patients.

Methods: Clinical features, brain magnetic resonance imaging/computed tomography (MRI/CT), and brain ¹⁸F-THK-5351 PET were recorded in five patients with the APP p.D678H mutation and correlated with brain ¹⁸F-AV-45 PET images. We also compared the tau deposition patterns among five patients with familial mild cognitive impairment (fMCI), six patients with sporadic amnestic mild cognitive impairment (sMCI), nine patients with mild to moderate dementia due to Alzheimer's disease (AD), and 12 healthy controls (HCs). All of the subjects also received brain ¹⁸F-AV-45 PET.

Results: The nine patients with sAD and six patients with sMCI had a positive brain AV-45 PET scans, while the 12 HCs had negative brain AV-45 PET scans. All five patients with fMCI received a tau PET scan with the age at onset ranging from 46 to 53 years, in whom increased standard uptake value ratio (SUVR) of ¹⁸F-THK-5351 was noted in all seven brain cortical areas compared with the HCs. In addition, the SUVRs of ¹⁸F-THK-5351 were increased in the frontal, medial parietal, lateral parietal, lateral temporal, and occipital areas (P < 0.001) in the patients with sAD compared with the HCs. The patients with fMCI had a significant higher SUVR of ¹⁸F-THK-5351 in the cerebellar cortex compared to the patients with sMCI. The correlations between regional SUVR and Mini-Mental State Examination score and between regional SUVR and clinical dementia rating (sum box) scores within volumes of interest of Braak stage were statistically significant.

Conclusion: Tau deposition was increased in the patients with fMCI compared to the HCs. Increased regional SUVR in the cerebellar cortical area was a characteristic finding in the patients with fMCI. As compared between amyloid and tau PET, the amyloid deposition is diffuse, but tau deposition is limited to the temporal lobe in the patients with fMCI.

Depression related cerebral pathology and its relationship with cognitive functioning: A systematic review

BACKGROUND

Depression's relationship with cerebral abnormalities and cognitive decline is temporally dynamic. Despite clear clinical utility, understanding depression's effect on cerebral structures, cognitive impairment and the interaction between these symptoms has had limited consideration.

METHODS

This review summarised studies examining a clinical depression diagnosis or validated scales measuring depressive symptoms, data concerning amyloid-beta (Aβ) levels, brain structure and function focusing on hippocampal alterations, or white matter hyperintensities (WMH), and at least one validated neuropsychological test. Online database searches of: PsycINFO, EMBASE, MEDLINE, and Scopus were conducted to identify potential articles.

RESULTS

While depression was consistently associated with cross-sectionally cognitive decline across multiple domains, the neuropathological basis of this dysfunction remained unclear. Hippocampal, frontal, and limbic dysfunction as well as cortical thinning, WMH, and Aβ burden all provide inconsistent findings, likely due to depression subtypes. The consistency of these findings additionally decreases when examining this relationship longitudinally, as these results are further confounded by pre-dementia states. The therapeutic interventions examined were more efficacious in the younger compared with the older samples, who were characterised by greater WMH and Aβ burden.

LIMITATIONS

The limited number of longitudinal and interventional studies in addition to the heterogeneity of the samples restricts their generalisability.

CONCLUSIONS

Symptomatological differences between early-onset and late-onset depression (EOD and LOD) appear crucial in understanding whether late-life depression is the primary or secondary source of cerebral pathology. Though severe cognitive impairments and clearer neuropathological underpinnings are more characteristic of LOD than EOD, the inconsistency of valid biomarkers remains problematic.

Progress of Brain Amyloid Deposition in Familial Alzheimer's Disease with Taiwan D678H APP Mutation

BACKGROUND

The amyloid AV-45 (florbetapir) positron emission tomography (PET) has been used in the study of the familial Alzheimer's disease (FAD) with the D678H amyloid precursor protein (APP) mutation. In addition, the progress of the disease remains unknown.

OBJECTIVE

We aim to investigate the progression rate of amyloid accumulation in FAD patients with this mutation by neuroimages analysis.

METHODS

The clinical course, changes in cognitive function, brain magnetic resonance imaging (MRI) and 18F-AV-45 PET scan were investigated in FAD patients and sporadic AD (sAD) patients. We compared the amyloid deposition pattern in serial brain 18F-AV-45 PET scan among the FAD, familial mild cognitive impairment (FMCI), and sMCI and sAD patients.

RESULTS

Seven familial patients received a follow-up survey. The follow up duration for brain AV-45 PET was from 1.54 to 3.61 years. In 4 FMCI patients, an increased regional SUVR was noted, and the annual change rates were increased from 1.03% to 18.82%. However, a decreased regional SUVR was noted in 3 FAD patients and the annual change rates were from -2.62% to -16.03%. As compared with the sAD and sMCI patients, the annual change rate is statistically significant in FAD and FMCI patients respectively.

CONCLUSIONS

The data indicate a biphasic course with an initial increase and then a decrease of SUVR in brain amyloid PET scan in familial APP mutation patients. The data also reveal that the novel Taiwan APP (D678H) mutation has a more amyloid burden than the sAD patients, particularly in an MCI stage.

Diversity of neurodegenerative pathophysiology in nondemented patients with major depressive disorder: Evidence of cerebral amyloidosis and hippocampal atrophy

BACKGROUND

Patients with late-life depression may be at the preclinical stage of dementia. However, the neurodegenerative processes in late-life depression are poorly understood. This study aimed to investigate the distribution patterns of amyloid pathology and neurodegeneration in a depressive population without dementia.

METHODS

The study recruited 63 middle-aged and elderly patients with major depressive disorder (MDD) and 22 control subjects. The MDD patients were further subdivided into those with mild cognitive impairment (MCI) (n = 24) and non-MCI (n = 39) patients. We used the global standardized uptake value ratio of ¹⁸ F-florbetapir (AV-45/Amyvid) positron emission tomography imaging as a biomarker of cerebral amyloidosis and the hippocampal volume as a biomarker for neurodegeneration. Cutoff points of brain amyloid positivity and hippocampal atrophy were determined using independent data obtained from clinically diagnosed Alzheimer's disease (AD) patients in a previous study.

RESULTS

Most of the control subjects (81.8%) were biomarker-negative, in contrast to the MCI MDD patients (37.5%). A relatively high proportion of the MCI MDD patients (12.5%) exhibited both amyloid positivity and hippocampal atrophy as compared to the control subjects (4.5%) and non-MCI patients (5.1%). However, a considerable proportion of the MCI MDD patients (29.2%) were categorized into the group with hippocampal atrophy alone, and negative amyloid deposition, as compared to the control subjects (0%) and non-MCI patients (5.1%).

CONCLUSIONS

This study highlights the expected heterogeneity of the processes of neurodegeneration in MDD patients. The diverse neurodegenerative processes may have important etiologic and therapeutic implications regarding neurodegenerative pathophysiology in late-life depression.

Plasma Amyloid-β and Alzheimer's Disease-Related Changes in Late-Life Depression

To elucidate an involvement of amyloid dysmetabolism in the pathophysiology of depression, we investigated associations of plasma amyloid-β (Aβ) levels with Alzheimer's disease-related changes in neuroimaging and cognitive dysfunction in patients with late-life depression. Higher plasma Aβ40, but not Aβ42 nor Aβ40/Aβ42 ratio, was associated with higher degree of parahippocampal atrophy and lower verbal fluency performance. Indeed, high plasma Aβ40 predicted poor cognitive prognosis of depressed patients with mild cognitive impairment. As an anti-depressive treatment, electroconvulsive therapy (ECT) resulted in a marginally significant reduction of plasma Aβ40 compared to pharmacotherapy alone, suggesting protective effects of ECT against amyloid dysmetabolism.

Plasma Aβ analysis using magnetically-labeled immunoassays and PET 18F-florbetapir binding in non-demented patients with major depressive disorder

An increased level of brain amyloid deposition and a decreased level of cerebral spinal fluid (CSF) Aβ42 are currently considered reliable biomarkers of Alzheimer’s disease (AD); however, the usefulness of plasma Aβ levels are not well-established. This study investigated the relationships between plasma Aβ levels and cerebral amyloidosis in 36 non-demented patients with major depressive disorder (MDD). All participants underwent ¹⁸F-florbetapir PET imaging and provided a blood sample at the same time for immunomagnetic reduction assay to measure the plasma levels of Aβ40 and Aβ42. We found inverse associations of the plasma Aβ42 level and the Aβ42/Aβ40 ratio, and a positive association of the plasma Aβ40 level, with cerebral amyloid deposition in the precuneus, parietal and posterior cingulate cortex. Subgroup analyses in subjects with higher ¹⁸F-florbetapir uptake values or MDD with amnestic mild cognitive impairment revealed more pervasive relationships of plasma Aβ measures with ¹⁸F-florbetapir binding across the brain regions examined. The study suggested that regional brain amyloid deposition in terms of ¹⁸F-florbetapir PET uptake had weak-to-moderate associations with plasma Aβ42 and Aβ40 levels, and the Aβ42/Aβ40 ratio. Validation in a larger population of subjects of known cerebral amyloidosis status is needed. Careful interpretation of plasma data is warranted.

Whole Brain Voxel-Wise Analysis of Cerebral Retention of Beta-Amyloid in Cognitively Normal Older Adults Using 18F-Florbetaben

OBJECTIVE

Recently developed 18F-labelled amyloid beta (Aβ) positron emission tomography (PET) tracers have demonstrated potentials to enable more prevalent application of amyloid imaging in the clinical setting. The aim of this study is to demonstrate cerebral retention of Aβ in cognitively normal older adults, by implementing voxel-based analysis on images acquired from ¹⁸F-Florbetaben amyloid PET.

METHODS

Fifty cognitive normal elderly subjects were recruited and included in the study. Demographic data and cognitive measurements were collected. Magnetic resonance imaging (MRI) and ¹⁸F-Florbetaben PET data were obtained followed by whole brain voxel-based analysis.

RESULTS

Compared to the florbetaben (FBB) (-) counterpart, FBB (+) showed significantly higher Aβ deposition in the brain regions comprising anterior cingulate, middle cingulate, posterior cingulate and precuneus (family wise error corrected p<0.05). There was no significant correlation between amyloid retention and cognitive functions.

CONCLUSION

Our results confirms previous results regarding Aβ deposition by using ¹⁸F-Florbetaben, demonstrating potentials in application of ¹⁸F-Florbetaben PET imaging in clinical settings.

Beta-amyloid deposition in patients with major depressive disorder with differing levels of treatment resistance: a pilot study

BACKGROUND

Lack of treatment response in patients with late-life depression is common. The role of brain beta-amyloid (Aβ) deposition in treatment outcome in subjects with late-life depression remains unclear. The present study aimed to investigate brain Aβ deposition in patients with major depressive disorder (MDD) with differing treatment outcomes in vivo using ¹⁸F-florbetapir imaging. This study included 62 MDD patients and 18 healthy control subjects (HCs).We first employed the Maudsley staging method (MSM) to categorize MDD patients into two groups according to treatment response: mild treatment resistance (n = 29) and moderate-to-severe treatment resistance (n = 33).The standard uptake value ratio (SUVR) of each volume of interest was analysed, and voxel-wise comparisons were made between the MDD patients and HCs. Vascular risk factors, serum homocysteine level, and apolipoprotein E (ApoE) genotype were also determined.

RESULTS

The MDD patients with moderate-to-severe treatment resistance had higher ¹⁸F-florbetapir SUVRs than the HCs in the parietal region (P < 0.01). Voxel-wise comparisons further demonstrated elevated SUVRs in MDD patients with moderate-to-severe treatment resistance in the precuneus, parietal, temporal, and occipital regions. The MDD patients with mild treatment resistance were found to have increased ¹⁸F-florbetapir uptake mainly in the left frontal and parietal regions as compared with the HCs. In addition, voxel-to-voxel correlation analysis showed that brain Aβ deposition was correlated positively with MSM score in the occipital region. ¹⁸F-florbetapir SUVRs were correlated negatively with Mini Mental Status Examination (MMSE) score in the sample of all MDD patients (r = -0.355, P = 0.005).

CONCLUSIONS

This study provided preliminary evidence that region-specific Aβ deposition was present in some (but not all) MDD patients, especially in those with moderate-to-severe treatment resistance, and their depressive symptoms may represent prodromal manifestations of Alzheimer's disease (AD). Depressive symptomatology in old age, particularly in subjects with a poor treatment response, may underscore early changes of AD-related pathophysiology.

Magnetic resonance imaging and positron emission tomography in the diagnosis of neurodegenerative dementias

Neuroimaging, both with magnetic resonance imaging (MRI) and positron emission tomography (PET), has gained a pivotal role in the diagnosis of primary neurodegenerative diseases. These two techniques are used as biomarkers of both pathology and progression of Alzheimer's disease (AD) and to differentiate AD from other neurodegenerative diseases. MRI is able to identify structural changes including patterns of atrophy characterizing neurodegenerative diseases, and to distinguish these from other causes of cognitive impairment, e.g. infarcts, space-occupying lesions and hydrocephalus. PET is widely used to identify regional patterns of glucose utilization, since distinct patterns of distribution of cerebral glucose metabolism are related to different subtypes of neurodegenerative dementia. The use of PET in mild cognitive impairment, though controversial, is deemed helpful for predicting conversion to dementia and the dementia clinical subtype. Recently, new radiopharmaceuticals for the in vivo imaging of amyloid burden have been licensed and more tracers are being developed for the assessment of tauopathies and inflammatory processes, which may underlie the onset of the amyloid cascade. At present, the cerebral amyloid burden, imaged with PET, may help to exclude the presence of AD as well as forecast its possible onset. Finally PET imaging may be particularly useful in ongoing clinical trials for the development of dementia treatments. In the near future, the use of the above methods, in accordance with specific guidelines, along with the use of effective treatments will likely lead to more timely and successful treatment of neurodegenerative dementias.

Vascular depression consensus report - a critical update

BACKGROUND

Vascular depression is regarded as a subtype of late-life depression characterized by a distinct clinical presentation and an association with cerebrovascular damage. Although the term is commonly used in research settings, widely accepted diagnostic criteria are lacking and vascular depression is absent from formal psychiatric manuals such as the Diagnostic and Statistical Manual of Mental Disorders, 5^th edition - a fact that limits its use in clinical settings. Magnetic resonance imaging (MRI) techniques, showing a variety of cerebrovascular lesions, including extensive white matter hyperintensities, subcortical microvascular lesions, lacunes, and microinfarcts, in patients with late life depression, led to the introduction of the term "MRI-defined vascular depression".

DISCUSSION

This diagnosis, based on clinical and MRI findings, suggests that vascular lesions lead to depression by disruption of frontal-subcortical-limbic networks involved in mood regulation. However, despite multiple MRI approaches to shed light on the spatiotemporal structural changes associated with late life depression, the causal relationship between brain changes, related lesions, and late life depression remains controversial. While postmortem studies of elderly persons who died from suicide revealed lacunes, small vessel, and Alzheimer-related pathologies, recent autopsy data challenged the role of these lesions in the pathogenesis of vascular depression. Current data propose that the vascular depression connotation should be reserved for depressed older patients with vascular pathology and evident cerebral involvement. Based on current knowledge, the correlations between intra vitam neuroimaging findings and their postmortem validity as well as the role of peripheral markers of vascular disease in late life depression are discussed.

CONCLUSION

The multifold pathogenesis of vascular depression as a possible subtype of late life depression needs further elucidation. There is a need for correlative clinical, intra vitam structural and functional MRI as well as postmortem MRI and neuropathological studies in order to confirm the relationship between clinical symptomatology and changes in specific brain regions related to depression. To elucidate the causal relationship between regional vascular brain changes and vascular depression, animal models could be helpful. Current treatment options include a combination of vasoactive drugs and antidepressants, but the outcomes are still unsatisfying.

Association of Cerebral Amyloidosis, Blood Pressure, and Neuronal Injury with Late-Life Onset Depression

Previous literature suggests that Alzheimer's disease (AD) process may contribute to late-life onset depression (LLOD). Therefore, we investigated the association of LLOD with cerebral amyloidosis and neuronal injury, the two key brain changes in AD, along with vascular risks. Twenty nine non-demented individuals who first experienced major depressive disorder (MDD) after age of 60 years were included as LLOD subjects, and 27 non-demented elderly individuals without lifetime experience of MDD were included as normal controls (NC). Comorbid mild cognitive impairment (MCI) was diagnosed in 48% of LLOD subjects and in 0% of NC. LLOD, irrespective of comorbid MCI diagnosis, was associated with prominent prefrontal cortical atrophy. Compared to NC, LLOD subjects with comorbid MCI (LLOD_MCI) showed increased cerebral ¹¹C-Pittsburg compound B (PiB) retention and plasma beta-amyloid 1–40 and 1–42 peptides, as measures of cerebral amyloidosis; and, such relationship was not observed in overall LLOD or LLOD without MCI (LLOD_woMCI). LLOD subjects, particularly the LLOD_woMCI, had higher systolic blood pressure (SBP) than NC. When analyzed in the same multiple logistic regression model that included prefrontal gray matter (GM) density, cerebral amyloidosis, and SBP as independent variables, only prefrontal GM density showed a significant independent association with LLOD regardless of MCI comorbidity status. Our findings suggest AD process might be related to LLOD via prefrontal neuronal injury in the MCI stage, whereas vascular processes—SBP elevation, in particular—are associated with LLOD via prefrontal neuronal injury even in cognitively intact or less impaired individuals.