AGTR1 gene variation: association with depression and frontotemporal morphology

Renin-angiotensin system: The underlying mechanisms and promising therapeutical target for depression and anxiety

Emotional disorders, including depression and anxiety, contribute considerably to morbidity across the world. Depression is a serious condition and is projected to be the top contributor to the global burden of disease by 2030. The role of the renin-angiotensin system (RAS) in hypertension and emotional disorders is well established. Evidence points to an association between elevated RAS activity and depression and anxiety, partly through the induction of neuroinflammation, stress, and oxidative stress. Therefore, blocking the RAS provides a theoretical basis for future treatment of anxiety and depression. The evidence for the positive effects of RAS blockers on depression and anxiety is reviewed, aiming to provide a promising target for novel anxiolytic and antidepressant medications and/or for improving the efficacy of currently available medications used for the treatment of anxiety and depression, which independent of blood pressure management.

POLYMORPHISM OF ACE AND AT2R1 GENES AS A GENETIC BACKGROUND FOR DIFFERENT TYPES OF ENCEPHALOPATHIES

OBJECTIVE

The aim: To study the prevalence of ACE I/D and AT2R1 A1166C gene polymorphisms in patients with CTE, SVD, AIE, and PIE and to assess the influence of the presence of a particular genotype of the studied genes on the occurrence and/or progression of encephalopathies.

PATIENTS AND METHODS

Materials and methods: A total of 96 patients with encephalopathies of various genesis (chronic traumatic encephalopathy (CTE) n=26; chronic alcohol-induced encephalopathy (AIE) n=26; microvascular ischemic disease of the brain (or cerebral small vessel disease, (SVD)) n=18; post-infectious encephalopathy (PIE) n=26) were involved in the study. The molecular genetic study was performed in the molecular genetics laboratory of the State Institution «Reference Center for Molecular Diagnostics of the Ministry of Health of Ukraine», Kyiv. Statistical processing of the results was performed using the STATISTICA 10.0 program.

RESULTS

Results: In patients with various types of encephalopathies, probable changes in the frequency distribution of genotypes of polymorphic variants I/D of the ACE gene were established (11.11% vs. 33.33% - carriers of the I/I genotype, 27.78% vs. 50.00% - carriers of the I/D genotype and 61.11% vs. 16.67% - carriers of the D/D genotype) and A1166C of the AT2R1 gene (22.22% vs. 66.67% - carriers of the A/A genotype, 50.00% vs. 25.00% - carriers A/C genotype, 27.78% versus 8.33% - carriers of the C/C genotype) compared to individuals of the control group only in patients with SVD. The presence of the D allele and the D/D genotype of the ACE gene is associated with a statistically significant increase in the risk of SVD development and progression (respectively, 4.2 times (95% CI (1.39-12.72)) and 7.9 (95% CI ( 1.31-47.05)) times). A similar trend was established for the carrier of the C allele of the A1166C polymorphic variant of the AT2R1 gene in patients with SVD: a 4.3-fold increase in the risk of development and progression (95% CI (1.30-13.86). In addition, there is a probable dependence between carrier genotype A/C of the AT2R1 gene and increased risk of PIE and AIE by 4.8 and 5.7 times, respectively.

CONCLUSION

Conclusions: Therefore, results suggest the reasonability to include the I/D of the ACE gene polymorphism investigation in the genetic panel of encephalopathies.

Genetic Polymorphism in Angiotensinogen and Its Association with Cardiometabolic Diseases

Angiotensinogen (AGT) is one of the most significant enzymes of the renin-angiotensin-aldosterone system (RAAS) which is involved in the regulation and maintenance of blood pressure. AGT is involved in the production of angiotensin I which is then converted into angiotensin II that leads to renal homeostasis. However, various genetic polymorphisms in AGT have been discovered in recent times which have shown an association with various diseases. Genetic polymorphism increases the level of circulating AGT in blood which exaggerates the effects produced by AGT. The associated diseases occur due to various effects produced by increased AGT levels. Several cardiovascular diseases including myocardial infarction, coronary heart disease, heart failure, hypertrophy, etc. are associated with AGT polymorphism. Other diseases such as depression, obesity, diabetic nephropathy, pre-eclampsia, and liver injury are also associated with some variants of AGT gene. The most common variants of AGT polymorphism are M235T and T174M. The two variants are associated with many diseases. Some other variants such as G-217A, A-6G, A-20C and G-152A, are also present but they are not as significant as that of M235T and T174M variants. These variants increase the level of circulating AGT and are associated with prevalence of different diseases. These diseases occur through various pathological pathways, but the initial reason remains the same, i.e., increased level of AGT in the blood. In this article, we have majorly focused on how genetic polymorphism of different variants of AGT gene is associated with the prevalence of different diseases.

The new mechanism of cognitive decline induced by hypertension: High homocysteine-mediated aberrant DNA methylation

The prevalence and severity of hypertension-induced cognitive impairment increase with the prolonging of hypertension. The mechanisms of cognitive impairment induced by hypertension primarily include cerebral blood flow perfusion imbalance, white and gray matter injury with blood-brain barrier disruption, neuroinflammation and amyloid-beta deposition, genetic polymorphisms and variants, and instability of blood pressure. High homocysteine (HHcy) is an independent risk factor for hypertension that also increases the risk of developing early cognitive impairment. Homocysteine (Hcy) levels increase in patients with cognitive impairment induced by hypertension. This review summarizes a new mechanism whereby HHcy-mediated aberrant DNA methylation and exacerbate hypertension. It involves changes in Hcy-dependent DNA methylation products, such as methionine adenosyltransferase, DNA methyltransferases, S-adenosylmethionine, S-adenosylhomocysteine, and methylenetetrahydrofolate reductase (MTHFR). The mechanism also involves DNA methylation changes in the genes of hypertension patients, such as brain-derived neurotrophic factor, apolipoprotein E4, and estrogen receptor alpha, which contribute to learning, memory, and attention deficits. Studies have shown that methionine (Met) induces hypertension in mice. Moreover, DNA hypermethylation leads to cognitive behavioral changes alongside oligodendroglial and/or myelin deficits in Met-induced mice. Taken together, these studies demonstrate that DNA methylation regulates cognitive dysfunction in patients with hypertension. A better understanding of the function and mechanism underlying the effect of Hcy-dependent DNA methylation on hypertension-induced cognitive impairment will be valuable for early diagnosis, interventions, and prevention of further cognitive defects induced by hypertension.

Maternal anxiety, depression and vascular function during pregnancy

OBJECTIVE

We aim to clarify whether type and timing of mental health symptoms in early pregnancy distinctly contribute to maternal-fetal vascular function, independent from the psychotropic medications given to treat these conditions.

METHODS

Data from a prospective cohort study (n = 1678) were used to test whether self-reported fears about giving birth and depressive symptoms prior to 16 weeks of gestation were associated with vascular outcomes predictive of hypertensive disorders of pregnancy (HDP) i.e., systolic and diastolic blood pressure (BP); uterine artery pulsatility index (UAPI); umbilical artery resistance index (UmbARI); and urine protein creatinine ratio. Multiple linear regressions models and mediation models were used to test for associations between predictors and outcomes, controlling for previously identified risk factors for vascular dysfunction such as maternal age and history of infertility.

RESULTS

Fears about giving birth in early pregnancy were inversely associated with UmbARI (β = -0.33, p = 0.03, df = 51) mid- to late-pregnancy (≥20 weeks). Depressive symptoms in early pregnancy were also inversely associated with maternal systolic BP (β = -0.13, p = 0.01, df = 387) and diastolic BP (β = -0.10, p = 0.04, df = 387) during the first trimester.

CONCLUSIONS

While fears about giving birth in early pregnancy were associated with lower vascular resistance in the fetal-placental unit, early depressive symptoms were associated with lower maternal vascular tone. At the very least, our results support the notion that early maternal psychological distress is unlikely to account for the development of HDP later during pregnancy and provide preliminary evidence to support distinct roles of pregnancy-related anxiety and depressive symptoms in maternal-fetal vascular function.

[Prognosis of the functional outcome of schizophrenia using a multigene panel]

OBJECTIVE

To compare the groups of schizophrenic patients with different levels of functional outcome and different frequency of risk variants in polymorphic loci of five candidate genes to create a multigene panel and to test its predictive ability for long-term outcome of the disease.

MATERIAL AND METHODS

According to the proposed typology, the patients included in the studies were divided into three groups, which differed in the level of social functioning. Group 1 was characterized by the highest level, in group 2 this indicator was significantly lower, and in group 3 the lowest. The multigenic panel included genes for serotonin receptor type 2a (5-HTR2A T102C), serotonin transporter (5-HTTLPR), C-reactive protein (CRP -717A>G), angiotensin II receptor type 1 (AGTR1 A1166C), and brain neurotrophic factor (BDNF Val66Met). A multi-gene risk score was calculated for each patient by summing the total number all his/her risk alleles. For each polymorphism, a score of 2 was assigned to homozygous high-risk genotypes, a score of 1 to heterozygous genotypes and a score of 0 to homozygous low-risk genotype. Accordingly, the multi-gene risk score for a patient could vary from 0 to 10 risk alleles.

RESULTS

A significant effect of the group on the multi-gene risk score was shown (p<0.0001). Between-group differences were significant as well (p<0.01). In group 1, there were no carriers of ≥6 risk alleles, and the number of carriers of less than 5 alleles exceeded 50%. In group 2, the number of carriers of ≥6 risk alleles was 19.4%, and in group 3 - 31.7%. Moreover, in these groups there were no carriers of 0-2 risk alleles, while in group 1 their number was 20.7%.

CONCLUSION

The multi-gene risk score predicts the level of functional outcome in patients with schizophrenia. In the case of a smaller number of risk alleles (0-4) in an individual, a favorable functional outcome can be predicted with a high probability in the long-term period of the disease.

Late-Life Depression: A Narrative Review on Risk Factors and Prevention

After participating in this activity, learners should be better able to:• Identify risk factors for late-life depression• Evaluate strategies to prevent late-life depression ABSTRACT: Late-life depression (LLD) is one of the major sources of morbidity and mortality in the world. Because LLD is related to increased public health burden, excess health care costs and utilization, reduced quality of life, and increased mortality, prevention is a priority. Older adults differ from younger adults with respect to key features, such as their chronicity and lifetime burden of depression and their constellation of comorbidities and risk factors. LLD likely arises from a complex interplay of risk factors, including medical, physiologic, psychosocial, behavioral, and environmental factors. Thus, a comprehensive understanding of LLD risk factors is necessary to inform prevention strategies. In this narrative literature review, we address both the risk architecture of LLD and several potential strategies for prevention. Our description of LLD risk factors and prevention approaches is informed by the framework developed by the National Academy of Medicine (formerly, Institute of Medicine), which includes indicated, selective, and universal approaches to prevention.

Targeting the renin angiotensin system for the treatment of anxiety and depression

Emotional disorders like anxiety and depression are responsible for considerable morbidity and mortality all over the world. Several antidepressant and anxiolytic medications are available for the treatment of anxiety and depression. However, a significant number of patients either do not respond to these medications or respond inadequately. Hence, there is a need to identify novel targets for the treatment of anxiety and depression. In this review we focus on the renin angiotensin system (RAS) as a potential target for the treatment of these disorders. We review work that has evaluated the effects of various compounds targeting the RAS on anxiety- and depression-like behaviors. Further, we suggest future work that must be carried out to fully exploit the RAS for the treatment of anxiety and depression. The RAS provides an attractive target for both the identification of novel anxiolytic and antidepressant medications and/or for enhancing the efficacy of currently available medications used for the treatment of anxiety and depression.

Association between Depression and Renal Hyperfiltration in a General Chinese Population

BACKGROUND

Depression is prevalent in patients with all stages of CKD and is associated with adverse outcome. Abnormally elevated GFR, or hyperfiltration, may play a crucial role in the initiation and progression of CKD. However, the association between depression and hyperfiltration is not known. The aim of this study is to investigate the relationship between depression and hyperfiltration.

METHODS

This was an observational cross-sectional study. A total of 3,716 volunteers (1,303 males and 2,413 females) aged 40-75 years without CKD from a community in China were included for the study. Depressive symptoms and the presence of a minor or major depressive episode were assessed with the 9-item Patient Health Questionnaire (PHQ-9) and Diagnostic and Statistical Manual of Mental Disorders (4th edition)-based structured interview, respectively.

RESULTS

The mean age of the participants in the present study was 53.8 ± 9.0 years. 115 participants had clinically relevant depression, and 122 participants had a minor or major depressive episode. In a multivariable logistic regression analysis adjusted for potential confounders, the association between clinically relevant depression and renal hyperfiltration remained significant in men but not in women. As compared with men without depression (PHQ <5) or depressive episodes, those with clinically relevant depression (PHQ ≥10) had a significantly higher risk of renal hyperfiltration. The fully adjusted OR (95% CI) was 4.81 (1.62-14.30, p = 0.005), those with a major depressive episode had a higher risk of renal hyperfiltration (OR 7.45; 95% CI 2.04-27.21, p = 0.002).

CONCLUSION

Depressive symptoms and major depressive episodes are associated with renal hyperfiltration in middle-aged and elderly Chinese men without CKD. Future studies are needed to verify and clarify the role of depression in the development of abnormally high eGFR and CKD.

The effect of angiotensin AT1A inactivation on innate and learned fear responses in mice and its relationship to blood pressure

Angiotensin AT₁ receptors are implicated in behavioral and physiological processes associated with fear and stress. However, the precise role of AT₁ receptors in modulating fear-related behavior and its relation to their physiological effects remains unclear. Here, we examined innate and learned fear responses and their relationship to cardiovascular arousal in AT_1A receptor knockout (AT_1A^-/-) mice. Using synchronized video and blood pressure telemetry, we found that, in a novel test environment, AT_1A^-/- mice showed reduced neophobia but a similar rise in blood pressure, as compared to AT_1A^+/+ mice. In response to a discrete threat, footshock, both flight behavior and cardiovascular arousal were decreased in AT_1A^-/- mice. Reduced flight behavior was also observed in AT_1A^-/- mice in the elevated T-maze test. During fear conditioning, the immediate freezing response to the first shock, but not the rate of freezing acquisition was decreased in AT_1A^-/- mice. Likewise, AT_1A^-/- mice showed reduced freezing and pressor responses to the first re-exposure, but normal rate of freezing extinction over subsequent trials. Similarly, in the elevated T-maze, the rates of avoidance acquisition and escape learning remained unchanged in AT_1A^-/- mice. Finally, after re-exposure, AT_1A^-/- mice displayed altered c-Fos expression, compared to AT_1A^+/+ mice, in the hypothalamus and periaqueductal gray but not in fear-related limbic-cortical areas, nor in medullary nuclei that convey visceral afferent information. We conclude that AT_1A receptor knockout reduces innate fear responses, without affecting learning efficiency in mice. These effects are dissociable from cardiovascular effects and likely reflect altered neurotransmission in hypothalamic-midbrain defense regions.

Association of depression with mortality in an elderly treated hypertensive population

ABSTRACTBackground:Both elevated blood pressure and/or depression increase the risk of cardiovascular disease and mortality. This study in treated elderly hypertensive patients explored the incidence of depression, its association (pre-existing and incident) with mortality and predictors of incident depression.

METHODS

Data from 6,083 hypertensive patients aged ≥65 years enrolled in the Second Australian National Blood Pressure study were used. Participants were followed for a median of 10.8 years (including 4.1 years in-trial) and classified into: "no depression," "pre-existing" and "incident" depression groups based on either being "diagnosed with depressive disorders" and/or "treated with an anti-depressant drug" at baseline or during in-trial period. Further, we redefined "depression" restricted to presence of both conditions for sensitivity analyses. For the current study, end-points were all-cause and any cardiovascular mortality.

RESULTS

313 (5%) participants had pre-existing depression and a further 916 (15%) participants developed depression during the trial period (incidence 4% per annum). Increased (hazard-ratio, 95% confidence-interval) all-cause mortality was observed among those with either pre-existing (1.23, 1.01-1.50; p = 0.03) or incident (1.26, 1.12-1.41; p &lt; 0.001) depression compared to those without. For cardiovascular mortality, a 24% increased risk (1.24, 1.05-1.47; p = 0.01) was observed among those with incident depression. The sensitivity analyses, using the restricted depression definition showed similar associations. Incident depression was associated with being female, aged ≥75 years, being an active smoker at study entry, and developing new diabetes during the study period.

CONCLUSIONS

This elderly cohort had a high incidence of depression irrespective of their randomised antihypertensive regimen. Both pre-existing and incident depression were associated with increased mortality.

Identification and bioinformatics analysis of overlapping differentially expressed genes in depression, papillary thyroid cancer and uterine fibroids

It is hypothesized that there may be common characteristics between the genetic regulatory networks of different diseases. To identify these potential similarities, analysis of overlapping differentially expressed genes (DEGs) in several diseases, which are believed to be associated in traditional Chinese medicine (TCM) was performed in the present study. The gene expression profiles associated with depression, papillary thyroid carcinoma (PTC) and uterine fibroids (UF) were preliminarily analyzed using Gene Expression Omnibus 2R tools. Gene Ontology enrichment analysis, Kyoto Encyclopedia of Genes and Genomes pathway analysis and protein-protein interaction network analysis of the overlapping DEGs in depression, PTC and UF was performed. The results indicated that multiple genes, including activating transcription factor 3 and WSC domain containing 2 and the phosphoinositide 3 kinase/protein kinase b signaling pathway and its downstream effectors may be common factors associated with depression, PTC and/or UF. The neuroendocrine functions of the hypothalamic-pituitary-ovarian axis and hypothalamic-pituitary-thyroid axis were also identified as being mutually associated with depression, PTC and/or UF. However, due to the limitations of DNA microassays, it is recommended that future studies take epigenetics into consideration. Further transcriptomic, methylomic and metabolomic analyses of depression, PTC and UF are also required to identify and elucidate the key associated biomarkers. In conclusion, the results of the current study shed light on the potential genetic interconnections between depression, PTC and UF, which may be beneficial for understanding their underlying coregulatory mechanisms and contributing to the development of homeotherapy based on bioinformatics prediction.

Unravelling the Lesser Known Facets of Angiotensin II Type 1 Receptor

PURPOSE OF REVIEW

Hypertension is an important risk factor in various pathologies. Despite enormous advancements in health sciences, the number of hypertensive individuals is increasing worldwide. The complex interplay between genetic and epigenetic factors seems to be a promising pathway to exploring the pathophysiology of hypertension.

RECENT FINDINGS

Various single gene and genome wide association studies have generated huge but non-reproducible data that highlights the role of some additional but as yet unidentified factor(s) in disease outcome. Dietary pattern and epigenetic mechanism (mainly DNA methylation) have shown a profound effect on blood pressure regulation. Angiotensin II and its receptors are known to play an important role in maintaining blood pressure; hence, a larger section of antihypertensive drugs targets the renin-angiotensin system (RAS). Angiotensin II type 1 receptor (AT1R), besides maintaining blood pressure, also has a role in cancer progression. Besides other pathways, RAS still remains the main player in blood pressure regulation. Additionally, AT1R has recently emerged as a molecule with diverse roles ranging from physiologic to cancer progression.

Neuroimaging genomic studies in major depressive disorder: A systematic review

Genetic-neuroimaging studies could identify new potential endophenotypes of major depressive disorder (MDD). Morphological and functional alterations may be attributable to genetic factors that regulate neurogenesis and neurodegeneration. Given that the association between gene polymorphisms and brain morphology or function has varied across studies, this systematic review aims at evaluating and summarizing all available genetic-neuroimaging studies. Twenty-eight gene variants were evaluated in 64 studies by structural or functional magnetic resonance imaging. Significant genetic-neuroimaging associations were found in monoaminergic genes, BDNF genes, glutamatergic genes, HPA axis genes, and the other common genes, which were consistent with common hypotheses of the pathogenesis of MDD.

Defining the Relationship Between Hypertension, Cognitive Decline, and Dementia: a Review

Hypertension is a highly prevalent condition which has been established as a risk factor for cardiovascular and cerebrovascular disease. Although the understanding of the relationship between cardiocirculatory dysfunction and brain health has improved significantly over the last several decades, it is still unclear whether hypertension constitutes a potentially treatable risk factor for cognitive decline and dementia. While it is clear that hypertension can affect brain structure and function, recent findings suggest that the associations between blood pressure and brain health are complex and, in many cases, dependent on factors such as age, hypertension chronicity, and antihypertensive medication use. Whereas large epidemiological studies have demonstrated a consistent association between high midlife BP and late-life cognitive decline and incident dementia, associations between late-life blood pressure and cognition have been less consistent. Recent evidence suggests that hypertension may promote alterations in brain structure and function through a process of cerebral vessel remodeling, which can lead to disruptions in cerebral autoregulation, reductions in cerebral perfusion, and limit the brain's ability to clear potentially harmful proteins such as β-amyloid. The purpose of the current review is to synthesize recent findings from epidemiological, neuroimaging, physiological, genetic, and translational research to provide an overview of what is currently known about the association between blood pressure and cognitive function across the lifespan. In doing so, the current review also discusses the results of recent randomized controlled trials of antihypertensive therapy to reduce cognitive decline, highlights several methodological limitations, and provides recommendations for future clinical trial design.

Strategies for dementia prevention: latest evidence and implications

Dementia is a common and debilitating syndrome with enormous impact on individuals and societies. Preventing disease onset or progression would translate to public health and societal benefits. In this review, we discuss the latest evidence on interventions that may show promise for the prevention of cognitive decline. We appraise existing evidence primarily drawn from randomized controlled trials, systematic reviews, and meta-analyses, but also highlight observational studies in humans and relevant work in model organisms. Overall, there is currently limited evidence to support a cause-effect relationship between any preventive strategy and the development or progression of dementia. However, studies to date suggest that a multifactorial intervention comprising regular exercise and healthy diet, along with the amelioration of vascular risk factors, psychosocial stress, and major depressive episodes may be most promising for the prevention of cognitive decline. We discuss the challenges, future directions, and implications of this line of research.

The ACE Gene Is Associated with Late-Life Major Depression and Age at Dementia Onset in a Population-Based Cohort

OBJECTIVE

Depression and dementia in the elderly have been suggested to share similar risk factors and pathogenetic background, and recently the authors reported that the APOEɛ4 allele is a risk factor for both disorders in the general population. The aim of the present study was to examine the influence of the well-known polymorphisms rs1799752 in the angiotensin-converting enzyme (ACE) and rs5186 in the angiotensin receptor II type 1 (AGTR1) on late-life depression and dementia in a population-based Swedish cohort of older individuals followed over 12 years.

METHODS

In 2000-2001, 900 individuals underwent neuropsychiatric and neuropsychological examinations. Follow-up evaluations were performed in 2005-2006 and 2009-2010, and register data on dementia to 2012 were included. Cross-sectional associations between genotypes/alleles and depression and dementia at baseline and between genotypes/alleles and depression on at least one occasion during the study period and dementia onset to 2012 were investigated.

RESULTS

As previously found for rs1799752 in ACE, rs5186 in AGTR1 was associated with dementia at baseline (OR: 3.25 [CI: 1.42-7.06], z = 2.90, p = 0.004). These associations became substantially weaker, or disappeared, when dementia onset to 2012 was included. For rs1799752 this could be explained by a significant association with age at onset (mean: 79.5 [SD: 6.45] years for risk-genotype carriers and 81.7 [SD: 7.12] years for carriers of other genotypes, b = -2.43, t = -2.38, df = 192, p = 0.02). When individuals with major depression on at least one occasion were analyzed, a significant association (OR: 2.14 [95% CI: 1.13-4.20], z = 2.28, p = 0.02), remaining after exclusion of dementia, with rs1799752 in ACE was found.

CONCLUSION

In this population-based sample of older individuals, genetic variations in ACE seem to be important both for late-life major depression and dementia.

Systematic review and meta-analysis of genetic studies of late-life depression

Late-life depression (LLD) is thought to be multifactorial in etiology, including a significant genetic component. While a number of candidate gene studies have been carried out, results remain inconclusive. We undertook a systematic review of all genetic association studies of depression or depressive symptoms in late life published before February 2016, and performed meta-analyses on polymorphisms investigated in three or more independent studies. A total of 46 candidate gene studies examining 56 polymorphisms in 23 genes as well as a genome-wide association study (GWAS) were included. Meta-analyses were conducted for four polymorphisms using random effects models, of which three (APOE, BDNF, SLC6A4) were associated with LLD. These genes are implicated in hippocampal plasticity and stress reactivity, suggesting that dysregulation of these pathways may contribute to LLD. Despite using a large sample, the only GWAS published to date identified only one genome-wide significant locus in the 5q21 region. In the future, larger genetic studies specifically examining LLD, including non-hypothesis-driven GWAS, are required to further identify genetic determinants of LLD.

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 gene variants of the renin-angiotensin system with accelerated hippocampal volume loss and cognitive decline in old age

OBJECTIVE

Genetic factors confer risk for neuropsychiatric phenotypes, but the polygenic etiology of these phenotypes makes identification of genetic culprits challenging. An approach to this challenge is to examine the effects of genetic variation on relevant endophenotypes, such as hippocampal volume loss. A smaller hippocampus is associated with gene variants of the renin-angiotensin system (RAS), a system implicated in vascular disease. However, no studies to date have investigated longitudinally the effects of genetic variation of RAS on the hippocampus.

METHOD

The authors examined the effects of polymorphisms of AGTR1, the gene encoding angiotensin-II type 1 receptor of RAS, on longitudinal hippocampal volumes of older adults. In all, 138 older adults (age ≥60 years) were followed for an average of about 4 years. The participants underwent repeated structural MRI and comprehensive neurocognitive testing, and they were genotyped for four AGTR1 single-nucleotide polymorphisms (SNPs) with low pairwise linkage disequilibrium values and apolipoprotein E (APOE) genotype.

RESULTS

Genetic variants at three AGTR1 SNPs (rs2638363, rs1492103, and rs2675511) were independently associated with accelerated hippocampal volume loss over the 4-year follow-up period in the right but not left hemisphere. Intriguingly, these AGTR1 risk alleles also predicted worse episodic memory performance but were not related to other cognitive measures. Two risk variants (rs2638363 and rs12721331) interacted with the APOE4 allele to accelerate right hippocampal volume loss.

CONCLUSIONS

Risk genetic variants of the RAS may accelerate memory decline in older adults, an effect that may be conferred by accelerated hippocampal volume loss. Molecules involved in this system may hold promise as early therapeutic targets for late-life neuropsychiatric disorders.

LRRC4 haplotypes are associated with pituitary adenoma in a Chinese population

Pituitary adenoma results from accumulation of multiple genetic and/or epigenetic aberrations such as GNAS, MEN1, CNC, and FIPA. LRRC4 is relatively tissue-specific expressed gene in the normal brain and downregulated expression in glioma (87.5%), meningioma (80.9%), and pituitary adenoma (85.5%). It has been suggested that the aberrant expression of LRRC4 contributes to tumorigenesis in glioma. However, little is known yet about association between LRRC4 and risk of pituitary adenoma. In this study, we genotyped three LRRC4 haplotype-tagging SNPs (htSNP) by direct sequencing in case-control studies, which included 183 Han Chinese patients diagnosed with pituitary adenoma and 183 age-, gender-matched, and geographically matched Han Chinese controls. Haplotypes were reconstructed according to the genotyping data and linkage disequilibrium status of the htSNP. We observed statistically significant differences regarding the genotype TT + CT of rs6944446 in the NCA. Haplotype AC of rs3823994-rs6944446 is suggested to have a protective effect in the development of pituitary adenoma (OR 0.339; 95% CI 0.123-0.934). However, haplotype GT of rs3808058-rs6944446 (OR 1.575; 95% CI 1.048-2.368) and AGT of rs3823994-rs6944446-rs3808058 (OR 1.673; 95% CI 1.056-2.651) might be a risk factor for pituitary adenoma development. In a brief, the results support the hypothesis that polymorphisms or haplotypes in the LRRC4 may have important research significance and could be used to predict the risk of pituitary adenoma.

BDgene: a genetic database for bipolar disorder and its overlap with schizophrenia and major depressive disorder

BACKGROUND

Bipolar disorder (BD) is a common psychiatric disorder with complex genetic architecture. It shares overlapping genetic influences with schizophrenia (SZ) and major depressive disorder (MDD). Large numbers of genetic studies of BD and cross-disorder studies between BD and SZ/MDD have accumulated numerous genetic data. There is a growing need to integrate the data to provide a comprehensive data set to facilitate the genetic study of BD and its highly relevant diseases.

METHODS

BDgene database was developed to integrate BD-related genetic factors and shared ones with SZ/MDD from profound literature reading. On the basis of data from the literature, in-depth analyses were performed for further understanding of the data, including gene prioritization, pathway-based analysis, intersection analysis of multidisease candidate genes, and pathway enrichment analysis.

RESULTS

BDgene includes multiple types of literature-reported genetic factors of BD with both positive and negative results, including 797 genes, 3119 single nucleotide polymorphisms, and 789 regions. Shared genetic factors such as single nucleotide polymorphisms, genes, and regions from published cross-disorder studies among BD and SZ/MDD were also presented. In-depth data analyses identified 43 BD core genes; 70 BD candidate pathways; and 127, 79, and 107 new potential cross-disorder genes for BD-SZ, BD-MDD, and BD-SZ-MDD, respectively.

CONCLUSIONS

As a central genetic database for BD and the first cross-disorder database for BD and SZ/MDD, BDgene provides not only a comprehensive review of current genetic research but also high-confidence candidate genes and pathways for understanding of BD mechanism and shared etiology among its relevant diseases. BDgene is freely available at http://bdgene.psych.ac.cn.

The vascular depression hypothesis: mechanisms linking vascular disease with depression

The 'Vascular Depression' hypothesis posits that cerebrovascular disease may predispose, precipitate or perpetuate some geriatric depressive syndromes. This hypothesis stimulated much research that has improved our understanding of the complex relationships between late-life depression (LLD), vascular risk factors, and cognition. Succinctly, there are well-established relationships between LLD, vascular risk factors and cerebral hyperintensities, the radiological hallmark of vascular depression. Cognitive dysfunction is common in LLD, particularly executive dysfunction, a finding predictive of poor antidepressant response. Over time, progression of hyperintensities and cognitive deficits predicts a poor course of depression and may reflect underlying worsening of vascular disease. This work laid the foundation for examining the mechanisms by which vascular disease influences brain circuits and influences the development and course of depression. We review data testing the vascular depression hypothesis with a focus on identifying potential underlying vascular mechanisms. We propose a disconnection hypothesis, wherein focal vascular damage and white matter lesion location is a crucial factor, influencing neural connectivity that contributes to clinical symptomatology. We also propose inflammatory and hypoperfusion hypotheses, concepts that link underlying vascular processes with adverse effects on brain function that influence the development of depression. Testing such hypotheses will not only inform the relationship between vascular disease and depression, but also provide guidance on the potential repurposing of pharmacological agents that may improve LLD outcomes.