Circulating levels of brain-derived neurotrophic factor: correlation with mood, cognition and motor function

Brain-derived neurotrophic factor levels in late-life depression and comorbid mild cognitive impairment: a longitudinal study

Changes in brain-derived neurotrophic factor (BDNF) level are implicated in the pathophysiology of cognitive decline in depression and neurodegenerative disorders in older adults. We aimed to evaluate the longitudinal association over two years between BDNF and persistent cognitive decline in individuals with remitted late-life depression and Mild Cognitive Impairment (LLD + MCI) compared to either individuals with remitted LLD and no cognitive decline (LLD + NCD) or never-depressed, cognitively normal, elderly control participants. We additionally evaluated the effect of double-blind, placebo-controlled donepezil treatment on BDNF levels in all of the remitted LLD participants (across the levels of cognitive function). We included 160 elderly participants in this study (72 LLD + NCD, 55 LLD + MCI and 33 never-depressed cognitively normal elderly participants). At the same visits, cognitive assessments were conducted and blood sampling to determine serum BDNF levels were collected at baseline assessment and after one and two years of follow-up. We utilized repeated measure, mixed effect models to assess: (1) the effects of diagnosis (LLD + MCI, LLD + NCD, and controls), time, and their interaction on BDNF levels; and (2) the effects of donepezil treatment (donepezil vs. placebo), time, baseline diagnosis (LLD + MCI vs. LLD + NCD), and interactions between these contrasts on BDNF levels. We found a significant effect of time on BDNF level (p = 0.02) and a significant decline in BDNF levels over 2 years of follow-up in participants with LLD + MCI (p = 0.004) and controls (p = 0.04). We found no effect of donepezil treatment on BDNF level. The present results suggest that aging is an important factor related to decline in BDNF level. Clinicaltrials.gov Identifier: NCT00177671.

BDNF serum levels in subjects developing or not post-traumatic stress disorder after trauma exposure

Post-traumatic stress disorder (PTSD) is a syndrome resulting from exposure to a severe traumatic event that poses threatened death or injury and produces intense fear and helplessness. The neural structures implicated in PTSD development belong to the limbic system, an important region for emotional processing. Brain-derived neurotrophic factor (BDNF) is a neurotrophin that serves as survival factor for selected populations of central nervous system (CNS) neurons and plays a role in the limbic system by regulating synaptic plasticity, memory processes and behavior. Impaired BDNF production in the brain can lead to a variety of CNS dysfunctions including symptoms associated with PTSD. However, so far fewer studies have investigated this neurotrophin in patients with PTSD. Furthermore, given the multiple role of BDNF in various CNS disorders, it cannot be excluded that traumatic events per se may influence neurotrophin levels, without a direct association to the PTSD syndrome. To elucidate these issues, in this study we analyzed BDNF serum levels in two groups of subjects: patients with trauma exposure who developed PTSD, and subjects with trauma exposure who did not develop PTSD. We found that BDNF serum levels were lower in PTSD patients as compared to related control subjects. Thus, these data suggest that BDNF might be involved in pathophysiology of PTSD and consequently therapeutic approaches aimed at restoring BDNF serum levels may be beneficial to this pathology.

Neuroplasticity and the next wave of antidepressant strategies

Depression is a common chronic psychiatric disorder that is also often co-morbid with numerous neurological and immune diseases. Accumulating evidence indicates that disturbances of neuroplasticity occur with depression, including reductions of hippocampal neurogenesis and cortical synaptogenesis. Improper trophic support stemming from stressor-induced reductions of growth factors, most notably brain derived neurotrophic factor (BDNF), likely drives such aberrant neuroplasticity. We posit that psychological and immune stressors can interact upon a vulnerable genetic background to promote depression by disturbing BDNF and neuroplastic processes. Furthermore, the chronic and commonly relapsing nature of depression is suggested to stem from "faulty wiring" of emotional circuits driven by neuroplastic aberrations. The present review considers depression in such terms and attempts to integrate the available evidence indicating that the efficacy of current and "next wave" antidepressant treatments, whether used alone or in combination, is at least partially tied to their ability to modulate neuroplasticity. We particularly focus on the N-methyl-D-aspartate (NMDA) antagonist, ketamine, which already has well documented rapid antidepressant effects, and the trophic cytokine, erythropoietin (EPO), which we propose as a potential adjunctive antidepressant agent.

Serum neurotrophic factors in adolescent depression: gender difference and correlation with clinical severity

BACKGROUND

Brain derived neurotrophic factor (BDNF), nerve growth factor (NGF), neurotrophin-3 (NT-3) and glial cell line derived neurotrophic factor (GDNF) play critical role in growth, differentiation, maintenance and synaptic plasticity in neuronal systems which is more relevant in adolescence. The present study was undertaken to verify the 'neurotrophin hypothesis' in adolescent depression by (i) comparing serum concentrations of neurotrophic factors in depression patients and healthy control, and (ii) analyzing correlations between clinical severity and serum neurotrophin levels.

METHODS

Eighty four adolescent (aged 13-18 years) depressed patients (56 males; 60 medication free/naive) and 64 healthy controls (39 males) were recruited. Severity of depression was measured by Beck's depression inventory, and anxiety by state-trait anxiety inventory. Measurement of serum neurotrophins was done by ELISA.

RESULTS

Adolescents with depression had significantly lower levels of BDNF: mean diff. (95% C.I.): 2093.9 (1074.0, 3113.9), NGF: 813.3 (343.1, 1283.6) and GDNF: 158.8 (77.2, 240.4) compared to controls. On gender based analysis female controls had significantly increased trait anxiety scores [-1.1 (-1.8, -0.1)], as compared to control males. In the patient group, female patients had far lower level of NGF: 919.6 (210.9, 1628.3) and NT-3: 1288.8 (145.4, 2432.3) compared to male. BDI-II score showed a statistically significant (p<0.01) negative correlation with all four neurotrophins in male patients while in female patients such negative correlation was observed only with NGF and GDNF (p<0.01).

LIMITATIONS

The study is cross-sectional from a tertiary care hospital.

CONCLUSION

The novelty of the study lies in its large number of exclusively adolescent depression patients showing significant reduction of BDNF, NGF and GDNF serum levels as compared to controls. A gender bias with much reduction in female has also been recorded.

Serum brain-derived neurotrophic factor levels in different neurological diseases

Consistent evidence indicates the involvement of the brain-derived neurotrophic factor (BDNF) in neurodegenerative disorders such as Alzheimer's disease (AD) and Parkinson's disease (PD). In the present study, we compared serum BDNF in 624 subjects: 266 patients affected by AD, 28 by frontotemporal dementia (FTD), 40 by Lewy body dementia (LBD), 91 by vascular dementia (VAD), 30 by PD, and 169 controls. Our results evidenced lower BDNF serum levels in AD, FTD, LBD, and VAD patients (P < 0.001) and a higher BDNF concentration in patients affected by PD (P = 0.045). Analyses of effects of pharmacological treatments suggested significantly higher BDNF serum levels in patients taking mood stabilizers/antiepileptics (P = 0.009) and L-DOPA (P < 0.001) and significant reductions in patients taking benzodiazepines (P = 0.020). In conclusion, our results support the role of BDNF alterations in neurodegenerative mechanisms common to different forms of neurological disorders and underline the importance of including drug treatment in the analyses to avoid confounding effects.

Biomarkers in Parkinson's disease (recent update)

Parkinson's disease (PD) is the second most common neurodegenerative disorder mostly affecting the aging population over sixty. Cardinal symptoms including, tremors, muscle rigidity, drooping posture, drooling, walking difficulty, and autonomic symptoms appear when a significant number of nigrostriatal dopaminergic neurons are already destroyed. Hence we need early, sensitive, specific, and economical peripheral and/or central biomarker(s) for the differential diagnosis, prognosis, and treatment of PD. These can be classified as clinical, biochemical, genetic, proteomic, and neuroimaging biomarkers. Novel discoveries of genetic as well as nongenetic biomarkers may be utilized for the personalized treatment of PD during preclinical (premotor) and clinical (motor) stages. Premotor biomarkers including hyper-echogenicity of substantia nigra, olfactory and autonomic dysfunction, depression, hyposmia, deafness, REM sleep disorder, and impulsive behavior may be noticed during preclinical stage. Neuroimaging biomarkers (PET, SPECT, MRI), and neuropsychological deficits can facilitate differential diagnosis. Single-cell profiling of dopaminergic neurons has identified pyridoxal kinase and lysosomal ATPase as biomarker genes for PD prognosis. Promising biomarkers include: fluid biomarkers, neuromelanin antibodies, pathological forms of α-Syn, DJ-1, amyloid β and tau in the CSF, patterns of gene expression, metabolomics, urate, as well as protein profiling in the blood and CSF samples. Reduced brain regional N-acetyl-aspartate is a biomarker for the in vivo assessment of neuronal loss using magnetic resonance spectroscopy and T2 relaxation time with MRI. To confirm PD diagnosis, the PET biomarkers include [(18)F]-DOPA for estimating dopaminergic neurotransmission, [(18)F]dG for mitochondrial bioenergetics, [(18)F]BMS for mitochondrial complex-1, [(11)C](R)-PK11195 for microglial activation, SPECT imaging with (123)Iflupane and βCIT for dopamine transporter, and urinary salsolinol and 8-hydroxy, 2-deoxyguanosine for neuronal loss. This brief review describes the merits and limitations of recently discovered biomarkers and proposes coenzyme Q10, mitochondrial ubiquinone-NADH oxidoreductase, melatonin, α-synculein index, Charnoly body, and metallothioneins as novel biomarkers to confirm PD diagnosis for early and effective treatment of PD.

Reduced serum nerve growth factor in patients with late-life depression

INTRODUCTION

Nerve growth factor (NGF) is one of the most abundant neurotrophic factors in the central nervous system and has been involved in several neuropsychiatric disorders.

METHODS

We recruited 77 age- and gender-matched elderly subjects (38 with late-life depression, 17 with previous major depressive episode, and 22 healthy subjects in the comparison group). Serum concentration of NGF was determined by enzyme-linked immunosorbent assay.

RESULTS

NGF levels were significantly reduced in the depressed patients (p = 0.002) as compared with healthy elderly controls. Elderly control subjects with previous depressive episode also showed a significant reduction in NGF levels as compared with controls (p <0.01); NGF levels were similar between patients with current depressive episode and previous depressive episode (p = 0.2).

CONCLUSION

The present findings provide additional evidence to the relevance of reduced neurotrophic support in the pathophysiology of late-life depression. Also, reduced serum NGF level may be a state marker of depression in elderly subjects.

Molecular and neural bases underlying roles of BDNF in the control of body weight

Brain-derived neurotrophic factor (BDNF) is a potent regulator of neuronal development and synaptic plasticity that is fundamental to neural circuit formation and cognition. It is also involved in the control of appetite and body weight, with mutations in the genes for BDNF and its receptor, TrkB, resulting in remarkable hyperphagia and severe obesity in humans and mice. Recent studies have made significant progress in elucidating the source, action sites, and regulatory pathways of BDNF with regard to its role in the control of energy homeostasis, and have shed light on the relationships between BDNF and other molecules involved in the control of body weight. Here we provide a comprehensive review of evidence from pharmacological, genetic, and mechanistic studies, linking BDNF to the control of body weight. This review also aims to organize the main findings on this subject into a more refined framework and to discuss the future research directions necessary to advance the field.

Brain-derived neurotrophic factor plasma levels are associated with mortality in critically ill patients even in the absence of brain injury

Introduction

Because of its relevance to the functioning of the central nervous system, brain-derived neurotrophic factor (BDNF) has been implicated in the pathogenesis of different neuropsychiatric diseases. Whether the BDNF level can be a marker of brain dysfunction and thus predict mortality in critically ill patients is not known. Thus we aimed to determine whether the plasma levels of BDNF are associated with morbidity and mortality in critically ill patients.

Methods

Healthy volunteers (n = 40) and consecutive patients older than 18 years (n = 76) admitted for more than 24 hours in an Intensive Care Unit (ICU) in a University hospital between July and October 2010 were included in the present study. First blood samples were collected within 12 hours of enrollment (D0), and a second sample, 48 hours after (D2) for determination of plasma BDNF levels. The relation between BDNF levels and mortality was the primary outcome. The secondary outcomes were the relation between BDNF levels and delirium and coma-free days (DCFD) and ICU and hospital length of stay (LOS).

Results

Admission plasma levels of BDNF were higher in ICU patients when compared with healthy volunteers (1,536 (962) versus 6,565 (2,838) pg/ml). The mean BDNF D2 was significantly lower in nonsurvivor patients (5,865 (2,662) versus 6,741 (2,356) pg/ml). After adjusting for covariates, BDNF levels, the need for mechanical ventilation, and sepsis were associated with mortality. Even in patients without clinically detectable brain dysfunction, lower BDNF D2 levels were associated with mortality. BDNF D2 had a mild correlation to DCFD (r = 0.44), but not to ICU and hospital LOS. In addition, plasma BDNF did not correlate to different plasma cytokines and platelets levels.

Conclusions

The plasma levels of BDNF were independently associated with mortality, even in the absence of clinically detectable brain dysfunction.

Chronic clomipramine treatment restores hippocampal expression of glial cell line-derived neurotrophic factor in a rat model of depression

BACKGROUND

Because there is evidence that certain neurotrophic factors are involved in depression and the mechanism of antidepressant treatment, it is hypothesized that neurotrophic factors may also play a functional role in the etiology of depression and treatment. Glial cell line-derived neurotrophic factor (GDNF) is a member of the transforming growth factor (TGF-β)-super-family. We performed a study to assess the impact of chronic unpredictable stress (CUS) and clomipramine treatment on GDNF expression in the rat hippocampus.

METHOD

Using a rat model of CUS-induced depression, we administered clomipramine, one of the typical antidepressants, every day for 3 weeks starting 2 weeks after the beginning of the experiment. GDNF level in the hippocampus was detected by immunohistochemsitry, Western blot analysis, and reverse transcription-polymerase chain reaction (RT-PCR). Behavioral changes were measured by forced swimming test (FST) and open field test (OFT).

RESULTS

Animals exposed to CUS showed depression-like behavior and exhibited a significant decrease in GDNF expression in the hippocampus. Chronic clomipramine treatment reversed the behavioral deficits and the decrease in GDNF levels induced by CUS.

LIMITATION

The relatively small number of the depression-model rats may cause some bias of behavioral tests.

CONCLUSION

In our study, chronic clomipramine treatment restored GDNF expression in the hippocampus of CUS-induced depression rats, suggesting that GDNF is involved in the behavioral responses to antidepressants. The beneficial effects of clomipramine suggest that GDNF may be a viable target for new antidepressant drug development.

Neurotrophic factors in obsessive-compulsive disorder

In this cross-sectional study, we assessed the levels of neurotrophins (NF) of patients with obsessive-compulsive disorder (OCD) in different stages of treatment and their relationship with OCD clinical features. Forty patients with OCD and 40 healthy controls had Brain-Derived Neurotrophic Factor (BDNF), Nerve Growth Factor (NGF), and Glial Cell-Derived Neurotrophic Factor (GNDF) plasma levels measured by enzyme-linked immunosorbent assay (ELISA). Patients with OCD were further examined with the Obsessive-Compulsive Inventory-Revised, the Beck Depression Inventory, the Beck Anxiety Inventory, and the Sheehan Disability Scale (SDS). Patients with OCD exhibited significantly lower levels of BDNF and significantly increased levels of NGF as compared to healthy controls. In OCD, statistically significant negative correlations between BDNF levels and number of working days lost per week were found. Additional analyses revealed a statistically significant positive correlation between both NGF and GDNF and severity of washing symptoms. Plasma levels of NF were not affected by age, age at OCD onset, gender, major depressive disorder, the relative dose of serotonin-reuptake inhibitors being prescribed, or the use of antipsychotics. Our findings suggest that patients with OCD may exhibit a particular NF profile, with functional impairment correlating with BDNF levels and severity of washing symptoms correlating with NGF and GDNF levels.

Relationship between Sonic hedgehog protein, brain-derived neurotrophic factor and oxidative stress in autism spectrum disorders

The etiology of autism spectrum disorders (ASD) is not well known but oxidative stress has been suggested to play a pathological role. We report here that the serum levels of Sonic hedgehog (SHH) protein and brain-derived neurotrophic factor (BDNF) might be linked to oxidative stress in ASD. By using the whole blood or polymorphonuclear leukocytes, we demonstrated that autistic children produced a significantly higher level of oxygen free radicals (OFR). In addition, we found significantly higher levels of serum SHH protein in children with mild as well as severe form of autism. We also found that the serum level of BDNF was significantly reduced in autistic children with mild form of the disorder but not with severe form of the disorder. Our findings are the first to report a correlation between SHH, BDNF and OFR in autistic children, suggesting a pathological role of oxidative stress and SHH in autism spectrum disorders.

Expression of monoamine transporters, nitric oxide synthase 3, and neurotrophin genes in antidepressant-stimulated astrocytes

BACKGROUND

There is increasing evidence that glial cells play a role in the pathomechanisms of mood disorders and the mode of action of antidepressant drugs.

METHODS

To examine whether there is a direct effect on the expression of different genes encoding proteins that have been implicated in the pathophysiology of affective disorders, primary astrocyte cell cultures from rats were treated with two different antidepressant drugs, imipramine and escitalopram, and the RNA expression of brain-derived neurotrophic factor (Bdnf), serotonin transporter (5Htt), dopamine transporter (Dat), and endothelial nitric oxide synthase (Nos3) was examined.

RESULTS

Stimulation of astroglial cell culture with imipramine, a tricyclic antidepressant, led to a significant increase of the Bdnf RNA level whereas treatment with escitalopram did not. In contrast, 5Htt was not differentially expressed after antidepressant treatment. Finally, neither Dat nor Nos3 RNA expression was detected in cultured astrocytes.

CONCLUSION

These data provide further evidence for a role of astroglial cells in the molecular mechanisms of action of antidepressants.

Circulating Glial-derived neurotrophic factor is reduced in late-life depression

BACKGROUND

The Glial cell-line derived neurotrophic factor (GDNF) is part of the TGF-β superfamily and is abundantly expressed in the central nervous system. Changes in GDNF homeostasis have been reported in affective disorders.

AIM

To assess serum GDNF concentration in elderly subjects with late-life depression, before antidepressant treatment, as compared to healthy elderly controls.

METHODS

Thirty-four elderly subjects with major depression and 37 age and gender-matched healthy elderly controls were included in this study. Diagnosis of major depression was ascertained by the SCID interview for DSM-IV and the severity of depressive symptoms was assessed by the Hamilton Depression Rating Scale (HDRS-21). Serum GDNF concentration were determined by sandwich ELISA.

RESULTS

Patients with major depression showed a significant reduction in GDNF levels as compared to healthy elderly controls (p < 0.001). Also, GDNF level was negatively correlated with HDRS-21 scores (r = -0.343, p = 0.003).

DISCUSSION

Our data provide evidence that GDNF may be a state marker of depressive episode in older adults. Changes in the homeostatic control of GDNF production may be a target to development of new antidepressant strategies.

Serum levels of brain-derived neurotrophic factor correlate with the number of T2 MRI lesions in multiple sclerosis

The objective of the present study was to determine if there is a relationship between serum levels of brain-derived neurotrophic factor (BDNF) and the number of T2/fluid-attenuated inversion recovery (T2/FLAIR) lesions in multiple sclerosis (MS). The use of magnetic resonance imaging (MRI) has revolutionized the study of MS. However, MRI has limitations and the use of other biomarkers such as BDNF may be useful for the clinical assessment and the study of the disease. Serum was obtained from 28 MS patients, 18-50 years old (median 38), 21 women, 0.5-10 years (median 5) of disease duration, EDSS 1-4 (median 1.5) and 28 healthy controls, 19-49 years old (median 33), 19 women. BDNF levels were measured by ELISA. T1, T2/FLAIR and gadolinium-enhanced lesions were measured by a trained radiologist. BDNF was reduced in MS patients (median [range] pg/mL; 1160 [352.6-2640]) compared to healthy controls (1640 [632.4-4268]; P = 0.03, Mann-Whitney test) and was negatively correlated (Spearman correlation test, r = -0.41; P = 0.02) with T2/FLAIR (11-81 lesions, median 42). We found that serum BDNF levels were inversely correlated with the number of T2/FLAIR lesions in patients with MS. BDNF may be a promising biomarker of MS.

Cognitive impairment in Huntington disease: diagnosis and treatment

Cognition has been well characterized in the various stages of Huntington disease (HD) as well as in the prodrome before the motor diagnosis is given. Although the clinical diagnosis of HD relies on the manifestation of motor abnormalities, the associated impairments have been growing in prominence for several reasons. First, research to understand the most debilitating aspects of HD has suggested that cognitive and behavioral changes place the greatest burden on families, are most highly associated with functional decline, and can be predictive of institutionalization. Second, cognitive impairments are evident at least 15 years prior to the time at which motor diagnosis is given. Finally, cognitive decline is associated with biological markers such as brain atrophy, circulating levels of brain-derived neurotrophic factors, and insulin-like growth factor 1. Efforts are now underway to develop valid and reliable measures of cognition in the prodrome as well as in all stages of HD so that clinical trials can be conducted using cognitive outcomes.

Brain-derived neurotrophic factor and Alzheimer's disease: physiopathology and beyond

Brain-derived neurotrophic factor (BDNF) is the most widely distributed neurotrophin in the central nervous system where it plays several pivotal roles in synaptic plasticity and neuronal survival. As a consequence, BDNF became a key target in the physiopathology of several neurological and psychiatric diseases. Recent studies have reported altered levels of BDNF in the circulation, i.e. serum or plasma, of patients with Alzheimer's disease (AD), and low BDNF levels in the CSF as predictor of future cognitive decline in healthy older subjects. Altered BDNF circulating levels have also been reported in other neurodegenerative and psychiatric disorders, hampering its use as a specific biomarker for AD. Therefore, BDNF seems to be an unspecific biomarker of neuropsychiatric disorders marked by neurodegenerative changes.

Rapid antidepressant changes with sleep deprivation in major depressive disorder are associated with changes in vascular endothelial growth factor (VEGF): a pilot study

While conventional antidepressants benefit many patients with major depressive disorder (MDD), as much as eight to 12 weeks can elapse before significant improvements in depressive symptoms are seen. Treatments that act more rapidly in MDD are urgently needed. Sleep deprivation (SD) has been shown to produce a rapid antidepressant response within one day in 50-60% of patients with MDD; thus, identifying its antidepressant mechanism may contribute to the development of antidepressants that act more rapidly. The present study evaluated the effects of 39 h of SD on mood, as well as on plasma levels of brain derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) in patients with MDD. After a drug-free period of at least two weeks, 11 patients (6 males, 5 females; ages 25-62) who met DSM-IV criteria for MDD underwent total SD. Plasma samples for BDNF and VEGF assays were collected on Days 1 (baseline) and 2. The six-item Hamilton Rating Scale for Depression (HAMD-6) was the primary outcome measure. HAMD-6 scores decreased significantly after SD (Day 2). SD was negatively correlated with change in HAMD-6 score and change in VEGF levels, indicating that as depression scores decreased following SD, VEGF plasma levels increased. In contrast, SD did not alter plasma BDNF concentrations, nor was an association found between BDNF levels and clinical improvement on the HAMD-6. These results suggest that SD is associated with mood-related changes in plasma VEGF levels, but not plasma BDNF levels. Further studies using larger sample sizes are needed to confirm these preliminary findings.

Platelet GSK3B activity in patients with late-life depression: marker of depressive episode severity and cognitive impairment?

OBJECTIVE

Increased GSK3B activity has been reported as a state marker of major affective episodes in patients with depression and bipolar disorder. No study so far has addressed GSK3B activity in late-life depression. The aims of the present study were to determine GSK3B activity in platelets of elderly patients with major depression, and the association between GSK3B activity and the severity of depressive symptoms and cognitive impairment.

METHODS

Forty drug-free elderly patients with major depressive episode were compared to healthy older adults (n = 13). Severity of the depressive episode and current cognitive state were determined by the Hamilton Depression Scale (HAM-D) and the Cambridge Cognitive Test (CAMCOG), respectively. Total- and ser-9-phosphorylated GSK3B (tGSK3B and pGSK3B) were determined in platelets by enzyme immunometric assays (EIA). GSK3B activity was indirectly inferred by the GSK3B ratio (i.e. pGSK3B/tGSK3B).

RESULTS

Elderly depressed patients had significantly lower pGSK3B levels (P = 0.03) and GSK3B ratio (P = 0.03), indicating higher GSK3B activity. Higher GSK3B activity were observed in patients with severe depressive episode (HAM-D scores >22, P = 0.03) and with cognitive impairment (CAMCOG scores <86, P = 0.01).

CONCLUSION

The present findings provide additional evidence of the involvement of GSK3B in the pathophysiology of late-life major depression. Higher GSK3B activity may be more relevant in those patients with more severe depressive symptoms and cognitive impairment.