Depressive symptoms and CSF Alzheimer's disease biomarkers in relation to clinical symptom onset of mild cognitive impairment

Depressive Symptoms Are Not Associated with Predementia Cerebrospinal Fluid Amyloid Pathology

Introduction

Depressive symptoms are associated with Alzheimer's disease (AD), but their neurobiological and neuropsychological correlates remain poorly understood. We investigate if depressive symptoms are associated with amyloid (Aβ) pathology and cognition in predementia AD.

Methods

We included subjective cognitive decline (SCD, n = 160) and mild cognitive impairment (MCI, n = 192) from the dementia disease initiation cohort. Depressive symptoms were assessed using the Geriatric Depression Scale (GDS-15). Aβ pathology was determined using cerebrospinal fluid (CSF) Aβ42/40 ratio. Associations between depressive symptoms and cognition were assessed with logistic regression.

Results

Only the Aβ negative MCI group (MCI-Aβ-) was associated with depressive symptoms (odds ratio [OR] = 2.65, p = 0.005). Depressive symptoms were associated with worse memory in MCI-Aβ- (OR = 0.94, p = 0.039), but with better performance in MCI-Aβ+ (OR = 1.103, p = 0.001).

Conclusion

Our results suggest that depressive symptoms in MCI are neither associated with Aβ pathology, nor AD-associated memory impairment. However, memory impairment in non-AD MCI may relate to depressive symptoms.

Neurobiological correlation between phosphorylated tau and mood symptoms in memory clinic patients

BACKGROUND

Alzheimer's disease (AD) dementia and mild cognitive impairment are characterised by impaired cognition accompanied by neuropsychiatric symptoms (NPS) relating to mood, including depression, anxiety, and apathy. However, the utility of AD biomarkers for predicting mood symptoms of NPS remains controversial. Herein, we analyzed the relationship between phosphorylated tau (p-tau) and depression, anxiety, and apathy of NPS. We also examined the influence of genetic factors such as apolipoprotein E (APOE) ε4 on these relationships.

METHODS

We conducted a cross-sectional survey in older patients (n = 122) with normal cognition (n = 12), mild cognitive impairment (n = 46), and AD (n = 64) strictly diagnosed by the board of psychiatrists and neurologists of Hokkaido University. NPS of the patients were assessed using the Neuropsychiatric Inventory Questionnaire (NPI). All patients also received a lumbar puncture to obtain cerebral spinal fluid for assessment of p-tau. The inverse probability weighting method was used to adjust for demographic differences between the p-tau present group and the p-tau absent group.

RESULTS

There was an association between p-tau accumulation and decreased incidence of depression and apathy. APOE ε4 non-carriers also showed a trend toward a negative association between p-tau and depression, which was not evident in APOE ε4 carriers.

CONCLUSIONS

We provide new evidence for a negative correlation between p-tau and depression and apathy of NPS, which may be influenced by APOE ε4. Future longitudinal studies are required to confirm the utility of p-tau for predicting the course of mood symptoms in patients with cognitive decline.

Amyloid β-based therapy for Alzheimer's disease: challenges, successes and future

Amyloid β protein (Aβ) is the main component of neuritic plaques in Alzheimer's disease (AD), and its accumulation has been considered as the molecular driver of Alzheimer's pathogenesis and progression. Aβ has been the prime target for the development of AD therapy. However, the repeated failures of Aβ-targeted clinical trials have cast considerable doubt on the amyloid cascade hypothesis and whether the development of Alzheimer's drug has followed the correct course. However, the recent successes of Aβ targeted trials have assuaged those doubts. In this review, we discussed the evolution of the amyloid cascade hypothesis over the last 30 years and summarized its application in Alzheimer's diagnosis and modification. In particular, we extensively discussed the pitfalls, promises and important unanswered questions regarding the current anti-Aβ therapy, as well as strategies for further study and development of more feasible Aβ-targeted approaches in the optimization of AD prevention and treatment.

The Analysis of Oxidative Stress Markers May Increase the Accuracy of the Differential Diagnosis of Alzheimer's Disease with and without Depression

Introduction

The aim of work is to assess the usefulness of oxidative stress parameters in the differential diagnosis of dementia of the Alzheimer’s type and dementia of the Alzheimer’s type with coexisting depression.

Methods

The study involved three groups of people: patients with Alzheimer’s disease (AD) (AD; N=27), patients with Alzheimer’s disease and depression (D) (AD+D; N=30), and a control group that consisted of people without dementia and without depression (C; N=24). The assessment of cognitive functioning was carried out using among alia, Auditory Verbal Learning Test and Verbal Fluency Test. Furthermore, we determined the activity of superoxide dismutase (SOD-1) and superoxide anion radical.

Results

Multiple models with different combinations of independent variables showed that SOD together with Rey delayed recall were the best significant predictors of AD with the area under curve (AUC) of 0.893 (p = 0.001) and superoxide anion radical (O2^•−) together with verbal fluency – sharp objects were the best significant predictors of AD +D diagnosis with the AUC of 0.689 (p = 0.034).

Conclusion

This study confirmed the value of neuropsychological diagnosis and analysis of oxidative stress markers in the diagnosis of AD and major depressive disorder (MDD) in the course of AD. The combination of the use of biochemical markers and neuropsychological tests seems particularly important for differential diagnosis.

Comorbidity between Alzheimer's disease and major depression: a behavioural and transcriptomic characterization study in mice

BACKGROUND

Major depression (MD) is the most prevalent psychiatric disease in the population and is considered a prodromal stage of the Alzheimer's disease (AD). Despite both diseases having a robust genetic component, the common transcriptomic signature remains unknown.

METHODS

We investigated the cognitive and emotional behavioural responses in 3- and 6-month-old APP/PSEN1-Tg mice, before β-amyloid plaques were detected. We studied the genetic and pathway deregulation in the prefrontal cortex, striatum, hippocampus and amygdala of mice at both ages, using transcriptomic and functional data analysis.

RESULTS

We found that depressive-like and anxiety-like behaviours, as well as memory impairments, are already present at 3-month-old APP/PSEN1-Tg mutant mice together with the deregulation of several genes, such as Ciart, Grin3b, Nr1d1 and Mc4r, and other genes including components of the circadian rhythms, electron transport chain and neurotransmission in all brain areas. Extending these results to human data performing GSEA analysis using DisGeNET database, it provides translational support for common deregulated gene sets related to MD and AD.

CONCLUSIONS

The present study sheds light on the shared genetic bases between MD and AD, based on a comprehensive characterization from the behavioural to transcriptomic level. These findings suggest that late MD could be an early manifestation of AD.