Alterations of brain anatomy in mouse model of MDD created by replacement of homologous mouse DNA sequence with an illness-associated 6-base human CREB1 promoter sequence.

We have recently reported the creation and initial characterization of an etiology-based recombinant mouse model of a severe and inherited form of Major Depressive Disorder (MDD). This was achieved by replacing the corresponding mouse DNA sequence with a 6-base DNA sequence from the human CREB1 promoter that is associated with the development of MDD in men and women from families identified by probands with recurrent, early-onset MDD (RE-MDD). Individuals in these families are also at increased risk for childhood developmental disorders and late life neurodegenerative disorders. The current study used three-dimensional magnetic resonance microscopy (3D-MRM) to determine the effect of the resulting humanized mutation of the mouse Creb1 gene on the anatomy of the mouse brain. Homozygous mutant mice manifested prominent increases in the volume and surface area of the lateral ventricles, as well as reduced volume of the anterior corpus callosum, compared to age/sex-matched wild-type mice. No significant genotype effects were observed on the volume or surface area of total brain, or several brain regions sometimes observed to be abnormal in human depression, including hippocampus, amygdala, or striatum. These findings suggest that at least some forms of MDD result from abnormal brain development produced by inherited genetic variants.

Differential hippocampal gene expression and pathway analysis in an etiology-based mouse model of major depressive disorder.

We have recently reported the creation and initial characterization of an etiology-based recombinant mouse model of a severe and inherited form of Major Depressive Disorder (MDD). This was achieved by replacing the corresponding mouse DNA sequence with a 6-base DNA sequence from the human CREB1 promoter that is associated with MDD in individuals from families with recurrent, early-onset MDD (RE-MDD). In the current study, we explored the effect of the pathogenic Creb1 allele on gene expression in the mouse hippocampus, a brain region that is altered in structure and function in MDD. Mouse whole-genome profiling was performed using the Illumina MouseWG-6 v2.0 Expression BeadChip microarray. Univariate analysis identified 269 differentially-expressed genes in the hippocampus of the mutant mouse. Pathway analyses highlighted 11 KEGG pathways: the phosphatidylinositol signaling system, which has been widely implicated in MDD, Bipolar Disorder, and the action of mood stabilizers; gap junction and long-term potentiation, which mediate cognition and memory functions often impaired in MDD; cardiac muscle contraction, insulin signaling pathway, and three neurodegenerative brain disorders (Alzheimer's, Parkinson's, and Huntington's Diseases) that are associated with MDD; ribosome and proteasome pathways affecting protein synthesis/degradation; and the oxidative phosphorylation pathway that is key to energy production. These findings illustrate the merit of this congenic C57BL/6 recombinant mouse as a model of RE-MDD, and demonstrate its potential for highlighting molecular and cellular pathways that contribute to the biology of MDD. The results also inform our understanding of the mechanisms that underlie the comorbidity of MDD with other disorders.

No evidence of non-homologous insertions in mouse model of MDD created by replacement of homologous mouse DNA sequence with pathogenic 6-base human CREB1 promoter sequence.

We have recently reported the creation and initial characterization of the first etiology-based recombinant mouse model of major depressive disorder (MDD). This was achieved by replacing the corresponding mouse DNA sequence with a 6-base DNA sequence from the human CREB1 promoter that is associated with the development of MDD in families identified by probands with recurrent, early-onset MDD. The current study explored whether the desired homologous recombination event at the mouse Creb1 gene that resulted in the creation of the mouse model was also accompanied by insertions of the targeting vector at unintended non-homologous locations in the mouse genome. No evidence of insertions of targeting vector sequence was observed at regions other than the mouse Creb1 gene.

Replacement of homologous mouse DNA sequence with pathogenic 6-base human CREB1 promoter sequence creates murine model of major depressive disorder.

Major depressive disorder (MDD) is a leading cause of disability worldwide. Families with recurrent, early-onset MDD (RE-MDD), a severe, familial form of MDD, have provided an important resource for identifying and characterizing genetic variants that confer susceptibility to MDD and related disorders. Previous studies identified a rare, highly penetrant A(-115)G transition within the human CREB1 promoter that reduced promoter activity in vitro and was associated with depressive disorders in RE-MDD families. The development of an etiology-based recombinant animal model for MDD would facilitate the advancement of our limited understanding of the pathophysiology of MDD, as well as the development of improved treatments. Here we report the construction and initial characterization of a congenic mutant C57BL/6NTac mouse model that carries the human pathogenic sequence at the homologous position of the mouse Creb1 promoter. The recombinant strain exhibited decreases in reproductive capacity and pup survival that may be related to increased infant mortality observed in RE-MDD families; enlargement of the cerebral ventricles; reduced levels of CREB protein in the mouse cerebral cortex, as predicted from transfection experiments employing the pathogenic human CREB1 promoter; and alterations in two standardized behavioral tests, the forced swim and marble burying tests. These initial findings support the pathogenicity of the human A(-115)G promoter variant, and invite further characterization of this etiology-based recombinant animal model for MDD. Human promoter variants that have highly penetrant effects on disease expression provide an attractive opportunity for creating etiology-based mouse models of human diseases, with minimal disruption of the mouse genome.

Predicted gene sequence C10orf112 is transcribed, exhibits tissue-specific expression, and may correspond to AD7.

Case-control and prospective longitudinal studies have revealed an interaction of the anonymous D10S1423 234 bp allele with the APOE4 allele in determining the age-specific risk of Alzheimer's disease (AD). The D10S1423 polymorphism resides within intron 10 of open reading frame C10orf112, whose predicted product resembles a low-density lipoprotein receptor (NCBI Build 35.1). These observations suggest that the D10S1423 234 bp allele may be in linkage disequilibrium with a C10orf112 gene variant whose product interacts with the apoE4 lipoprotein. Our initial exploration of this hypothesis focused on validating the C10orf112 gene model. RT-PCR amplification from human hippocampal mRNA confirmed that 34 of the predicted 39 exons of C10orf112 were expressed in this brain region. Northern blots revealed 1.2 kb and 3.2 kb mRNA species that hybridize to a cDNA probe consisting of contiguous exons 23-26. Expression of these C10orf112 mRNA species was limited to a subset of brain regions and heart tissue.

Effects of the A(-115)G variant on CREB1 promoter activity in two brain cell lines: Interactions with gonadal steroids.

Major depressive disorder (MDD) is a leading contributor to disease burden worldwide. Previous genetic studies have revealed significant evidence of linkage of the CREB1 region to mood disorders among women from families with recurrent, early-onset MDD (RE-MDD), a severe and familial subtype of MDD. Systematic resequencing of the CREB1 gene in affected members of these families has identified rare sequence variants at positions -656 and -115 that appear to cosegregate with unipolar mood disorders in two large multigenerational families and three small nuclear families, respectively. Results from previous transfection experiments that employed constructs containing the wild-type or variant CREB1 promoters coupled to a reporter gene support the hypothesis that the A(-656) allele contributes to the development of MDD in women by selectively increasing the activity of the CREB1 promoter in brain cell lines exposed to 17 ß-estradiol. Analogous transfection experiments described in the current study revealed that the G(-115) promoter variant reduced promoter activity in CATH.a neuronal cells regardless of the hormonal environment, consistent with the observation that increased risk for unipolar mood disorders conferred by this allele was not limited by sex. The effects of CREB1 promoter variants on promoter activity, their influence on the development of mood disorders and related clinical features, and the interaction of their phenotypic expression with sex seem likely to be complex and allele-specific rather than a general property of the CREB1 locus. © 2010 Wiley-Liss, Inc.

D10S1423 identifies a susceptibility locus for Alzheimer's disease (AD7) in a prospective, longitudinal, double-blind study of asymptomatic individuals: results at 14 years.

Typical forms of Alzheimer's disease (AD) appear to be influenced by multiple susceptibility loci. This report describes the prospective, longitudinal, double-blind assessment of the age-specific risk of AD encountered by 325 asymptomatic first-degree relatives of AD probands who carried the D10S1423 (AD7) 234 bp allele, the APOE E4 allele, or both, after 14 years of systematic follow-up. A total of 30 incident cases of AD were detected during the first 3752 subject-years of surveillance. The effects of carrying either or both of the D10S1423 234 bp and APOE E4 alleles on the age-specific risk of developing AD were determined using Kaplan-Meier survival analysis. The risk of developing AD was the greatest for individuals who carried both alleles (Mantel-Cox statistic = 16.46, df = 3, P = 0.0009; Breslow statistic = 13.38, df = 3, P = 0.004). Cox proportional hazards models were developed to estimate the risk ratios for each genotype, controlling for the potential effects of age at recruitment, sex, and years of education. Only individuals who carried both risk alleles exhibited a risk ratio that differed significantly from 1 (risk ratio = 7.5, P = 0.002, 95% CI = 2.1-27.0). Neither age at recruitment, sex, nor years of education made significant contributions to the model, although women tended to be at greater risk (P = 0.06). Recent evidence that D10S1423 resides within open reading frame C10orf112, whose predicted product resembles a low-density lipoprotein receptor, suggests a molecular mechanism for this gene-gene interaction.

Genetic linkage of region containing the CREB1 gene to depressive disorders in families with recurrent, early-onset, major depression: a re-analysis and confirmation of sex-specific effect.

A previously published model-free linkage analysis of chromosome 2q33-35, highlighted by previous case-control studies and supported by within-family analyses employing the transmission disequilibrium test, revealed evidence of sex-specific linkage of the CREB1-containing region of 2q to unipolar mood disorders among women in 81 recurrent, early-onset, major depressive disorder (RE-MDD) families. Since it has been reported that the LODPAL program from S.A.G.E. v.4.0 used to conduct this previous linkage analysis suffers from an increased type I error rate that is exacerbated by covariates such as sex, we re-analyzed the evidence for this sex-specific linkage result using a simulation approach to estimate the empirical significance of our previous results. The results continue to support sex-specific linkage of the CREB1 region to mood disorders among women from families with RE-MDD. Moreover, these results have been supported by a host of additional published findings that implicate sequence variations in CREB1 in the sex-dependent development of syndromic mood disorders, as well as related clinical features and disorders.

Identification of a CREB-dependent serotonergic pathway and neuronal circuit regulating foraging behavior in Caenorhabditis elegans: a useful model for mental disorders and their treatments?

The cAMP-response element binding protein (CREB)-mediated cell signaling pathway is conserved through evolution and participates in a broad range of complex behaviors of divergent species including man. This study describes the integration of genetic, pharmacologic, and anatomic methods to elucidate a serotonergic signaling pathway by which the CREB homolog CRH-1 controls foraging rate (FR) in the model organism Caenorhabditis elegans, along with the complete neuronal circuit through which this pathway operates. In the anterior afferent arm of the circuit, CRH-1 controls FR by regulating the expression of tph-1, the sole structural gene for tryptophan hydroxylase, in serotonergic sensory (ADF) neurons whose post-synaptic effects are mediated through 5HT(2)-like SER-1 receptors. The posterior afferent limb of the circuit includes an interneuron (RIH) that does not express tph-1 and whose serotonergic phenotype is dependent on the contribution of this neurotransmitter from another source, probably the ADF neurons. The postsynaptic effects of the RIH interneuron are mediated through 5HT(1)-like SER-4 receptors. This model has potential utility for the study of clinical disorders and experimental therapeutics. Furthermore, the discovery of serotonergic neurons that depend on other sources for their neurotransmitter phenotype could provide a mechanism for rapidly altering the number and distribution of serotonergic pathways in developing and adult nervous systems, providing a dimension of functional complexity that has been previously unrecognized.

Effects of the G(-656)A variant on CREB1 promoter activity in a glial cell line: interactions with gonadal steroids and stress.

Major depressive disorder (MDD) constitutes a major public health problem worldwide and affects women twice as frequently as men. Previous genetic studies have revealed significant evidence of linkage of the CREB1 region to mood disorders among women from families with recurrent, early-onset MDD (RE-MDD), a severe and familial subtype of MDD. A rare G to A transition at position -656 in the CREB1 promoter cosegregates with mood disorders in women from these families, implicating CREB1 as a sex-related susceptibility gene for unipolar mood disorders. In the current study, the functional significance of the CREB1 promoter variant was determined using transfection experiments that employed constructs containing the wild-type or variant CREB1 promoters coupled to a reporter gene. The results support the hypothesis that the A(-656) allele contributes to the development of MDD in women by selectively altering the activity of the CREB1 promoter in glial cells exposed to 17 beta-estradiol. Furthermore, the exaggeration of this effect during a simulated stress condition may be relevant to reported gene-environment interactions that contribute to the emergence of MDD in clinical populations. The results of in silico analysis revealed four putative binding sites for transcription factors that are affected by the G to A transition at position -656, of which CP2 best fit the experimental observations.

Genetics of recurrent early-onset major depression (GenRED): final genome scan report.

OBJECTIVE: The authors carried out a genomewide linkage scan to identify chromosomal regions likely to contain genes that contribute to susceptibility to recurrent early-onset major depressive disorder, the form of the disorder with the greatest reported risk to relatives of index cases. METHOD: Microsatellite DNA markers were studied in 656 families with two or more such cases (onset before age 31 in probands and age 41 in other relatives), including 1,494 informative "all possible" affected relative pairs (there were 894 independent affected sibling pairs). Analyses included a primary multipoint allele-sharing analysis (with ALLEGRO) and a secondary logistic regression analysis taking the sex of each relative pair into account (male-male, male-female, female-female). RESULTS: Genomewide suggestive evidence for linkage was observed on chromosome 15q25-q26 (at 105.4 centimorgans [cM]). The authors previously reported genomewide significant linkage in this region in the first 297 families. In the secondary analysis, after empirical genomewide correction for multiple testing, suggestive linkage results were observed on chromosome 17p12 (28.0 cM, excess sharing in male-male and male-female pairs) and on chromosome 8p22-p21.3 (25.1 cM, excess sharing in male-male pairs). CONCLUSIONS: These regions of chromosomes 15q, 17p, and 8p might contain genes that contribute to susceptibility to major depression and related disorders. Evidence for linkage has been reported independently in the same regions of chromosome 15q for major depression and of chromosome 8p for related personality traits.

Reduced age-related cataracts among elderly persons who reach age 90 with preserved cognition: a biomarker of successful aging?

Tissue damage due to oxidative stress has been implicated in aging, memory loss, and cataract formation. We hypothesized that persons who achieved exceptional longevity with preserved cognition (successful aging [SAG]) would exhibit a lower rate of age-related cataract (ARC) than the general population. The age-specific rates of ARC for a group of 100 (50 male, 50 female) elderly persons who reached at least age 90 years with preserved cognition were compared to the corresponding rates of ARC reported in five population-based studies. The principal finding of this report was that the SAG group manifested a significant reduction in the age-specific rate and lifetime cumulative incidence of ARC compared to the general population. Steroid use, alcohol consumption, gout, and skin lesions resulting from excessive sun exposure emerged as risk factors. Our findings suggest that the progressive development of lens opacities may be reflective of degenerative events occurring more generally throughout the body.

Research agenda for DSM-V: diagnostic categories and criteria for neuropsychiatric syndromes in dementia.

Neuropsychiatric symptoms in dementia represent a major health burden for older adults. These symptoms are often more distressing, impairing, and costly than cognitive symptoms in dementia, yet they have been less coherently categorized in the various versions of the Diagnostic and Statistical Manual of Mental Disorders (DSM). The preponderance of literature on psychiatric symptoms in dementia has been in patients with Alzheimer's disease. Diagnostic criteria have been proposed for psychosis, depression, and sleep disturbance in Alzheimer's disease. "Agitation" also appears to be a clinically important behavioral complication of dementia that warrants further study. Beginning with further validation of these proposed diagnostic criteria, future research can guide a more clinically meaningful description of these syndromes in DSM-V. Advancing biotechnology offers promise for discoveries related to the etiology and treatment of these syndromes. New research in this field should encompass diverse populations and different types of dementia. The high emotional and economic costs of neuropsychiatric symptoms in dementia implore diagnostic refinement to facilitate improved treatment.

A collaborative study of the emergence and clinical features of the major depressive syndrome of Alzheimer's disease.

OBJECTIVE: This report provides a description of the prevalence and clinical features of the major depressive syndrome of Alzheimer's disease using data derived from structured diagnostic assessments of 243 patients with probable Alzheimer's disease and 151 nondemented elderly comparison subjects. METHOD: Subjects were characterized by a consortium of four Alzheimer's disease research centers and the Geriatric Psychiatry Branch of the National Institute of Mental Health. All sites administered the Clinical Assessment of Depression in Dementia, a structured, anchored diagnostic interview that was developed to reliably diagnose and characterize major depressive episodes in this population. RESULTS: Despite the use of a common, reliable methodology for the assessment and diagnosis of major depressive episodes, the prevalence of major depression in Alzheimer's disease ranged widely from 22.5% to 54.4% across the recruitment sites. The prevalence of major depressive episodes among Alzheimer's disease patients in the aggregate sample exceeded that for elderly comparison subjects and reached nearly 50% among the most severely demented patients. Alzheimer's disease patients with a current major depressive episode had earlier mean ages at onset, a higher mean Hamilton Depression Rating Scale score, and were more likely to be experiencing psychotic symptoms than those who had not developed a major depressive episode. Although the major depressive episodes of Alzheimer's disease patients and nondemented elderly comparison subjects included similar numbers of depressive symptoms, patients with Alzheimer's disease were more likely to report a diminished ability to concentrate or indecisiveness and less likely to experience sleep disturbances and feelings of worthlessness or excessive guilt during their major depressive episodes. None of the clinical features of major depression differed significantly in frequency among depressed Alzheimer's disease patients with mild, moderate, or severe dementia. Concurrent psychotic symptoms progressively increased with dementia severity. CONCLUSIONS: The high rate of major depressive episodes that occur after the onset of cognitive impairment among patients with Alzheimer's disease (the majority of whom had no premorbid history of major depression), common emergence in the early stages of dementia when symptoms of cognitive impairment are least likely to contribute to the syndromal diagnosis of major depression, and differences in the clinical presentations of the major depressive episodes of Alzheimer's disease patients and nondemented elderly comparison subjects, all support the validity of the major depressive syndrome of Alzheimer's disease. Our findings suggest that the major depressive syndrome of Alzheimer's disease may be among the most common mood disorders of older adults.

Genome survey for susceptibility loci for recurrent, early-onset major depression: results at 10cM resolution.

Recurrent (two or more episodes), early-onset (first episode at < or = 25 years) major depressive disorder (RE-MDD) is a strongly familial condition (lambda(first-degree relatives) = 8) whose malignant effects have a significant negative impact on the health and longevity of patients and their family members. The goal of this study was to identify candidate susceptibility loci that influence the development of RE-MDD. We completed a systematic survey of the human genome, conducted at an average resolution of 10 cM, for the identification of simple sequence tandem repeat polymorphisms (SSTRPs) that target susceptibility genes for RE-MDD by virtue of linkage disequilibrium. The efficiency of our association study was enhanced by genotyping pools of DNA from 100 adults with RE-MDD and 100 adult controls who had no personal or family history of mental disorders. Both groups included equal numbers of Caucasian men and women and were matched as closely as possible for age and ethnicity. Allelic associations with RE-MDD were observed for 19 of the 387 SSTRPs in the CHLC Human Screening Set/Weber Version 9. Sixteen of the 19 candidate susceptibility loci revealed significant allelic associations with RE-MDD in men (n = 7) or women (n = 9), but not in both sexes. Evidence for both risk and protective alleles was detected. Two of the candidate susceptibility loci reside within several Mb of loci previously reported-megabases to be linked to "comorbid alcoholism and depression" in families of individuals with alcoholism and to a broadly defined affected phenotype that included recurrent major depression in the families of patients with bipolar disorder. Although it has been suggested that the genes that influence risk for MDD in the two sexes may not be entirely the same, the results of our study suggest that sex specificity of susceptibility loci for RE-MDD may be the rule rather than the exception. The observed preponderance of sex-specific susceptibility loci for RE-MDD suggests that there may be important differences in the molecular pathophysiology of RE-MDD in men and women. Alternatively, our findings may reflect the existence of sex-specific differences in the molecular mechanisms that determine resilience to endogenous or environmental depressogenic stimuli.

Genetic linkage of region containing the CREB1 gene to depressive disorders in women from families with recurrent, early-onset, major depression.

This report describes the results of a model-free linkage analysis of six polymorphic markers, located in a 15 cM region of chromosome 2q33-35, and unipolar Mood Disorders in 81 families identified by probands with Recurrent, Early-Onset Major Depressive Disorder (RE-MDD), a severe and familial form of clinical depression. Our findings reveal significant evidence of linkage of unipolar Mood Disorders to a 451 Kb region of 2q33-34 flanked by D2S2321 and D2S2208 in these families. Increasing peak LOD scores were observed in both the single point and multipoint analyses for Mood Disorder phenotypes whose definitions embodied progressively less stringent severity criteria for inclusion in the affected group. The sex-dependent multipoint linkage analysis of any Major or Minor Mood Disorders produced LOD scores that reached 6.331 and 6.866 at D2S2321 and D2S2208, respectively. Linkage of Mood Disorders to this region was observed exclusively among female affected relative pairs; no suggestion of linkage was observed when male affected relative pairs were analyzed. These observations imply that a sex-specific susceptibility gene in this region contributes to the vulnerability of women in these families to the development of unipolar Mood Disorders that ranged in severity from minor to severe at the time of clinical assessment. The region between the markers that yielded the peak LOD score includes the CREB1 gene, which encodes a cAMP-responsive element-binding protein (CREB) that is a member of the bZIP family of transcription factors. Based on considerable clinical and preclinical evidence, CREB1 is an attractive candidate for a susceptibility gene for unipolar Mood Disorders. The sex-specificity of the susceptibility locus identified by our study may result from reported synergistic interactions of CREB with nuclear estrogen receptors.

Genetic segregation analysis of recurrent, early-onset major depression: evidence for single major locus transmission.

Coordinated efforts are now underway to identify susceptibility genes for unipolar major depressive disorder (MDD) and related disorders. These studies have focused on recurrent, early-onset MDD (RE-MDD), thought to be the most familial form of this disorder. The goal of this study was to conduct a complex segregation analysis of recurrent MDD and other major mood disorders aggregating in families identified by probands with RE-MDD. Eighty-one families were identified through probands over the age of 18 who met criteria for recurrent (> or =2 episodes), early-onset (< or =25 years), nonpsychotic, unipolar MDD (RE-MDD) and included 407 first-degree relatives and 835 extended relatives. Psychiatric diagnoses for probands and their family members who provided blood samples were formulated from structured personal interviews, structured family history assessments, and available medical records. The remaining family members who participated and those who were deceased were evaluated through the family history method augmented by available medical records. Best-estimate diagnoses were made during a consensus conference according to established diagnostic criteria. Segregation analyses were performed using the REGD routine in S.A.G.E. release 4.0. The segregation analysis of recurrent MDD supported a sex-independent Mendelian codominant model. Analysis of major mood disorders supported a sex-independent Mendelian dominant model. Interestingly, inclusion of spousal residual correlations provided better fitting models for recurrent MDD but not the broader phenotype of major mood disorders. Unlike unipolar MDD, the lifetime prevalence of bipolar I disorder in this sample of families did not exceed the reported population prevalence [Zubenko et al., 2001]. Our results suggest that a major locus contributes to the expression of recurrent MDD and possibly other major mood disorders within families identified by probands with RE-MDD. Due to the limitations of the segregation analysis model, our results cannot address whether the same major locus is segregating across families in our sample or whether multiple major loci are involved (genetic heterogeneity). The absence of aggregation of bipolar I disorder in these families strongly suggests that while the genetic determinants of unipolar and bipolar disorders may overlap, they are not identical. Our findings illustrate the advantage of employing families identified by probands with RE-MDD in studies designed to detect susceptibility loci for unipolar MDD and related disorders.

The Use of the Hamilton Rating Scale for Depression in Elderly Patients With Cognitive Impairment and Physical Illness.

The authors performed a prospective study to assess the impact of cognitive impairment and medical burden on the Hamilton Ratingh Scale for Depression (Ham-D) scores in older psychiatric inpatients. Over 1 year, all patients admitted to an acute-care geriatric psychiatry unit were assessed with an instrument that includes an anchored version of the 17-uten Ham-D. Ham-D scores of 72 patients who met DSM-III-R criteria for a major depressive episode were compared with the scores of 31 patients who did not. The scores of a depressed and nondepressed patients were significantly different on admission but not at discharge. By contrast, the Ham-D scores of 11 depressed patients with a primary dementia did not differ either on admission or at discharge from the scores of 61 depressed patients without dementia. Controlling for psychiatric diagnosis, cognitive impairment had no significant effect on Ham-D scores. Medical burden accounted for less than 6% of the variance in admission Ham-D yields valid ratings of the severity of depressive symptoms in elderly patients with a broad range of cognitive impairment and physical illness.