Hippocampal volume in geriatric depression

Brain-derived neurotrophic factor, stress and depression: a minireview

Brain-derived neurotrophic factor (BDNF) is a member of the nerve growth factor family, and is widely expressed in the adult mammalian brain. Besides its well known neuroprotective activity after traumatic brain injury the evidences regarding its activity dependent release by the pathophysiology of major depression are rapidly replicating. Considering the data that stress plays an important role by the development of depression which is characterized with prominent hippocampal cell death, as well as the well known neuroprotective effects of BDNF, we aimed to investigate the link between the BDNF, stress and depression. Thus we prepared a minireview in order to evaluate the neuroprotective role of BDNF by psychiatric disorders which are characterized with prominent neuronal cell death.

Pathways linking late-life depression to persistent cognitive impairment and dementia

There is a strong association between late-life depression, cognitive impairment, cerebrovascular disease, and poor cognitive outcomes, including progressive dementia, especially Alzheimer's disease. While neuroimaging evidence suggests that cerebrovascular disease plays a prominent role, it seems that depression alone may also confer substantial risk for developing Alzheimer's disease. The relationships between the prominent cerebrovascular changes, other structural abnormalities, specific forms of cognitive dysfunction, and increased risk for developing Alzheimer's disease among those with late-life depression have been difficult to reconcile. The varied findings suggest that there are likely multiple pathways to poor cognitive outcomes. We present a framework outlining multiple, non-mutually exclusive etiologic links between depression, cognitive impairment, and progressive decline, including dementia. Importantly, the model is both testable and falsifiable. Going forward, using models such as this to inform research should accelerate knowledge acquisition on the depression/dementia relationship that may be useful for dementia prevention, monitoring the impact of depression treatment on clinical status and course of illness.

Neuroimaging genetics: new perspectives in research on major depression?

OBJECTIVE

Stress-related changes in the hippocampus are influenced by genetic factors. To enhance our understanding of both the interaction between the brain, behaviour and genetics and of biological mechanisms in mood disorders neuroimaging genetics provide a good opportunity.

METHOD

A MEDLINE search was conducted to identify articles on neuroimaging genetics in major depression (MD).

RESULTS

Hippocampal volumes were found to be associated with polymorphisms in the promotor region of the serotonin transporter (5-HTTLPR) in patients with MD. Met-allele carriers of the BDNF (val66met) polymorphism had smaller hippocampal volumes in both patients and healthy controls when compared with homozygous val-allele carriers. Polymorphisms of the serotonin transporter (5-HTTLPR) and 5-HT1a receptor are associated with increased amygdala activation investigated with functional MRI in patients with MD.

CONCLUSION

Genetic variants seem to modulate the effects of stress on hippocampal volumes as well as amygdala activity as well as the development of the brain.

APOE related hippocampal shape alteration in geriatric depression

Late-onset depression often precedes the onset of dementia associated with the hippocampal degeneration. Using large deformation diffeomorphic metric mapping (LDDMM), we evaluated apolipoprotein E epsilon-4 allele (apoE E4) effects on hippocampal volume and shape in 38 depressed patients without the apoE E4, 14 depressed patients with one apoE E4, and 31 healthy comparison subjects without the apoE E4. The hippocampal volumes were manually assessed. We applied a diffeomorphic template generation procedure for creating the hippocampal templates based on a subset of the population. The LDDMM mappings were used to generate the hippocampal shape of each subject and characterize the surface deformation of each hippocampus relative to the template. Such deformation was modeled as random field characterized by the Laplace-Beltrami basis functions in the template coordinates. Linear regression was used to examine group differences in the hippocampal volume and shape. We found that there were significant hippocampal shape alternations in both depressed groups while the groups of depressed patients and the group of healthy subjects did not differ in the hippocampal volume. The depressed patients with one apoE E4 show more pronounced shape inward-compression in the anterior CA1 than the depressed patients without the apoE E4 when compared with the healthy controls without the apoE E4. Thus, hippocampal shape abnormalities in late-onset depressed patients with one apoE E4 may indicate future conversion of this group to AD at higher risk than depressed patients without the apoE E4.

Reduced hippocampal volumes associated with the long variant of the tri- and diallelic serotonin transporter polymorphism in major depression

Substantial evidence supports a role for dysfunction of the serotonin transporter (5-HTT) in the pathogenesis of major depression. The polymorphism of the serotonin transporter gene (5-HTTLPR) was found to be associated with reduced hippocampal volume in major depression. However, the original diallelic polymorphism was criticized, because the L-allele can be subtyped into La and Lg alleles, the latter of which is thought to be similar to the S-allele. Therefore, the study aim was to examine the influences of the triallelic (La-Lg-S system) and diallelic 5-HTTLPR on hippocampal volumes in patients with major depression and healthy controls. Using high-resolution MRI hippocampal volumes and polymorphisms (5-HTTLPR) were measured in 60 in-patients with major depression and 60 healthy controls. Patients with the La/La genotype had significantly smaller hippocampal gray and white matter than La/La controls. No significant differences were found between patients and controls with La/(Lg + S) or (Lg + S)/(Lg + S) genotype. Moreover, within the patient group the La/La homozygous genotype had significantly smaller hippocampal white matter volumes than the La/(Lg + S) or (Lg + S)/(Lg + S) genotype. In conclusion, with the diallelic as well as the triallelic system the homozygosity for the long-allele is associated with decreased hippocampal volumes in patients with major depression, but not in healthy controls, suggesting that disease or stress specific processes linked to the serotonergic system may enhance the vulnerability to morphological alterations.

Gray matter changes in late life depression--a structural MRI analysis

Multiple brain morphometric changes have been reported in late-life depression (LLD), mostly in studies comparing volumes of circumscribed brain areas. The aim of our study is to characterize the volumetric changes of multiple gray matter regions in relation to age of onset/duration of illness. We predicted that the association of gray matter volumes with total duration of illness and age of onset would differ depending on whether the region was susceptible to the toxic effects of chronic exposure to cortisol or to the vascular/neurodegenerative changes accompanying prodromal dementia. Seventy-one elderly depressed subjects were studied along with thirty-two comparison subjects. High-resolution T1-weighted brain MRIs were processed using an automated labeling pathway technique. To protect against type-I error, we combined the right and left hemisphere volume data. We sampled 24 regions of interest (ROIs). We used the primary visual cortex volume to normalize for individual variations in brain size. LLD Subjects had smaller volumes than non-depressed subjects in 17 of the 24 examined ROIs. Shorter duration of illness and later age of onset was correlated with smaller volumes of parahippocampal area and parietal inferior area. A later age of onset was also correlated with smaller volumes of several frontal and temporal areas, cingulum, and putamen. Our findings support a dementia prodrome model more strongly than a toxic stress model in this group of subjects. However, it remains likely that both processes as well as other factors contribute to the heterogeneity of volumetric brain changes in LLD.

Mourning and melancholia revisited: correspondences between principles of Freudian metapsychology and empirical findings in neuropsychiatry

Freud began his career as a neurologist studying the anatomy and physiology of the nervous system, but it was his later work in psychology that would secure his place in history. This paper draws attention to consistencies between physiological processes identified by modern clinical research and psychological processes described by Freud, with a special emphasis on his famous paper on depression entitled 'Mourning and melancholia'. Inspired by neuroimaging findings in depression and deep brain stimulation for treatment resistant depression, some preliminary physiological correlates are proposed for a number of key psychoanalytic processes. Specifically, activation of the subgenual cingulate is discussed in relation to repression and the default mode network is discussed in relation to the ego. If these correlates are found to be reliable, this may have implications for the manner in which psychoanalysis is viewed by the wider psychological and psychiatric communities.

Hippocampal volumes and depression subtypes

Studies of depression and hippocampal volume have yielded inconsistent results. This inconsistency could stem from the heterogeneity of depressive disorders. We conducted cross-sectional and longitudinal analyses of hippocampal volumes in atypical depressive, melancholic depressive, and control subjects. We found no effect of depression subtype on hippocampal volume or memory performance.

Mapping callosal morphology in early- and late-onset elderly depression: an index of distinct changes in cortical connectivity

There is some evidence of corpus callosum abnormalities in elderly depression, but it is not known whether these deficits are region-specific or differ based on age at onset of depression. Twenty-four patients with early-onset depression (mean age = 68.00, SD+/-5.83), 22 patients with late-onset depression (mean age = 74.50, SD+/-8.09) and 34 elderly control subjects (mean age = 72.38; SD+/-6.93) were studied. Using 3D MRI data, novel mesh-based geometrical modeling methods were applied to compare the midsagittal thickness of the corpus callosum at high spatial resolution between groups. Neuropsychological correlates of midsagittal callosal area differences were additionally investigated in a subsample of subjects. Depressed patients exhibited significant callosal thinning in the genu and splenium compared to controls. Significant callosal thinning was restricted to the genu in early-onset patients, but patients with late-onset depression exhibited significant callosal thinning in both the genu and splenium relative to controls. The splenium of the corpus callosum was also significantly thinner in subjects with late- vs early-onset depression. Genu and splenium midsagittal areas significantly correlated with memory and attention functioning among late-onset depressed patients, but not early-onset depressed patients or controls. Circumscribed structural alterations in callosal morphology may distinguish late- from early-onset depression in the elderly. These findings suggest distinct abnormalities of cortical connectivity in late- and early-onset elderly depression with possible influence on the course of illness. Patients with a late onset of depression may be at higher risk of illness progression and eventually dementia conversion than early-onset depression, with potentially important implications for research and therapy.

Anterior cingulate dysfunction in geriatric depression

BACKGROUND

Although several brain abnormalities have been identified in geriatric depression, their relationship to the pathophysiological mechanisms leading to the development and perpetuation of this syndrome remain unclear.

METHODS

This paper reviews findings on the anterior cingulate cortex (ACC) function and on the relationship of ACC abnormalities to the clinical presentation and the course of geriatric depression in order to elucidate the pathophysiological role of ACC in this disorder.

RESULTS

The ACC is responsible for conflict detection and emotional evaluation of error and is connected to brain structures that regulate mood, emotional valence of thought and autonomic and visceral responses, which are functions disturbed in depression. Geriatric depression often is accompanied by abnormalities in some executive functions and has a clinical presentation consistent with ACC abnormalities. Indices of ACC dysfunction are associated with adverse outcomes of geriatric depression.

CONCLUSIONS

Converging findings suggest that at least some ACC functions are abnormal in depression and these abnormalities are pathophysiologically meaningful. Indices of ACC dysfunction may be used to identify subgroups of depressed elderly patients with distinct illness course and treatment needs and serve as the theoretical background for novel treatment development.

Hippocampus shape analysis and late-life depression

Major depression in the elderly is associated with brain structural changes and vascular lesions. Changes in the subcortical regions of the limbic system have also been noted. Studies examining hippocampus volumetric differences in depression have shown variable results, possibly due to any volume differences being secondary to local shape changes rather than differences in the overall volume. Shape analysis offers the potential to detect such changes. The present study applied spherical harmonic (SPHARM) shape analysis to the left and right hippocampi of 61 elderly subjects with major depression and 43 non-depressed elderly subjects. Statistical models controlling for age, sex, and total cerebral volume showed a significant reduction in depressed compared with control subjects in the left hippocampus (F_1,103 = 5.26; p = 0.0240) but not right hippocampus volume (F_1,103 = 0.41; p = 0.5213). Shape analysis showed significant differences in the mid-body of the left (but not the right) hippocampus between depressed and controls. When the depressed group was dichotomized into those whose depression was remitted at time of imaging and those who were unremitted, the shape comparison showed remitted subjects to be indistinguishable from controls (both sides) while the unremitted subjects differed in the midbody and the lateral side near the head. Hippocampal volume showed no difference between controls and remitted subjects but nonremitted subjects had significantly smaller left hippocampal volumes with no significant group differences in the right hippocampus. These findings may provide support to other reports of neurogenic effects of antidepressants and their relation to successful treatment for depressive symptoms.

Differential effects of depressive symptoms on prospective and retrospective memory in old age

The effects of depressive symptoms on prospective and retrospective memory were examined in a population-based sample of elderly persons (n = 404). Depression was assessed using the Comprehensive Psychopathological Rating Scale and treated as a continuous variable. The variation in depressive symptoms ranged from no symptoms to presence of a clinical depression. Depressive symptoms had a negative effect on consolidation and retrieval in retrospective memory. However, the retrospective, but not the prospective, component of prospective memory was affected by depression. The findings are discussed in light of medial-temporal lobe alterations in depression.

The As and Ds of stress: metabolic, morphological and behavioral consequences

Unlike responses to acute stressful events that are protective and adaptive in nature, chronic stress elicits neurochemical, neuroanatomical and cellular changes that may have deleterious consequences upon higher brain functioning. For example, while exposure to acute stress facilitates memory formation and consolidation, chronic stress or chronic exposure to stress levels of glucocorticoids impairs cognitive performance. Chronic stress or glucocorticoid exposure, as well as impairments in hypothalamic-pituitary-adrenal (HPA) axis function are proposed to participate in the etiology and progression of neurological disorders such as depressive illness, anxiety disorders and post-traumatic stress disorder (PTSD). HPA axis dysfunction, impaired stress responses and elevated basal levels of glucocorticoids are also hallmark features of experimental models of type 1 and type 2 diabetes, as well as diabetic subjects in poor glycemic control. Such results suggest that stress and glucocorticoids contribute to the neurological complications observed in diabetes patients. Interestingly, many of the hyperglycemia mediated changes in the brain are similar to those observed in depressive illness patients and in experimental models of chronic stress. Such results suggest that common mechanisms may be involved in the development of the neurological complications associated with Anxiety, Depressive illness and Diabetes: the As and Ds of stress. The aim of the current review will be to discuss the mechanisms through which limbic structures such as the hippocampus and amygdala respond and adapt to the deleterious consequences of chronic stress and hyperglycemia.

The neurobiology of retinoic acid in affective disorders

Current models of affective disorders implicate alterations in norepinephrine, serotonin, dopamine, and CRF/cortisol; however treatments targeted at these neurotransmitters or hormones have led to imperfect resolution of symptoms, suggesting that the neurobiology of affective disorders is incompletely understood. Until now retinoids have not been considered as possible contributors to affective disorders. Retinoids represent a family of compounds derived from vitamin A that perform a large number of functions, many via the vitamin A product, retinoic acid. This signaling molecule binds to specific retinoic acid receptors in the brain which, like the glucocorticoid and thyroid hormone receptors, are part of the nuclear receptor superfamily and regulate gene transcription. Research in the field of retinoic acid in the CNS has focused on the developing brain, in part stimulated by the observation that isotretinoin (13-cis retinoic acid), an isomer of retinoic acid used in the treatment of acne, is highly teratogenic for the CNS. More recent work has suggested that retinoic acid may influence the adult brain; animal studies indicated that the administration of isotretinoin is associated with alterations in behavior as well as inhibition of neurogenesis in the hippocampus. Clinical evidence for an association between retinoids and depression includes case reports in the literature, studies of health care databases, and other sources. A preliminary PET study in human subjects showed that isotretinoin was associated with a decrease in orbitofrontal metabolism. Several studies have shown that the molecular components required for retinoic acid signaling are expressed in the adult brain; the overlap of brain areas implicated in retinoic acid function and stress and depression suggest that retinoids could play a role in affective disorders. This report reviews the evidence in this area and describes several systems that may be targets of retinoic acid and which contribute to the pathophysiology of depression.

Hippocampal morphology and distinguishing late-onset from early-onset elderly depression

OBJECTIVE

Despite evidence for hippocampal abnormalities in elderly depression, it is unknown whether these changes are regionally specific. This study used three-dimensional mapping techniques to identify regional hippocampal abnormalities in early- and late-onset depression. Neuropsychological correlates of hippocampal morphology were also investigated.

METHOD

With high-resolution magnetic resonance imaging, hippocampal morphology was compared among elderly patients with early- (N=24) and late-onset (N=22) depression and comparison subjects (N=34). Regional structural abnormalities were identified by comparing distances, measured from homologous hippocampal surface points to the central core of each individual's hippocampal surface model, between groups.

RESULTS

Hippocampal volumes differed between depressed patients and comparison subjects but not between patients with early- and late-onset depression. However, statistical mapping results showed that regional surface contractions were significantly pronounced in late- compared to early-onset depression in the anterior of the subiculum and lateral posterior of the CA1 subfield in the left hemisphere. Significant shape differences were observed bilaterally in anterior CA1-CA3 subfields and the subiculum in patients in relation to comparison subjects. These results were similar when each disease group was separately compared to comparison subjects. Hippocampal surface contractions significantly correlated with memory measures among late- but not early-onset depressed patients or comparison subjects.

CONCLUSIONS

More pronounced regional volume deficits and their associations with memory in late-onset depression may suggest that these patients are more likely to develop cognitive impairment over time than individuals with early-onset depression. Mapping regional hippocampal abnormalities and their cognitive correlates may help guide research in defining risk profiles and treatment strategies.

Proteomic analysis of embryonic stem cell–derived neural cells exposed to the antidepressant paroxetine

Antidepressant drugs can have significant effects on the mood of a patient suffering from major depression or other disorders. The pharmacological actions of these drugs generally affect the uptake or metabolism of the neurotransmitters serotonin, noradrenalin, and, to a lesser extent, dopamine. However, many aspects of antidepressant action are not understood. We conducted a proteomic analysis in a neuronal cell culture model in an attempt to identify molecules important to the operation of pathways functionally relevant to antidepressant action. The model involved generating cultures containing mixed neural and glial cells by controlled differentiation of mouse embryonic stem cells, followed by exposure to 1 microM paroxetine for 14 days. After antidepressant exposure, we observed increased expression or modification of sepiapterin reductase (SPR), heat shock protein 9A, RAS and EF-hand domain containing, and protein disulfide isomerase associated 3 and decreased expression or modification of creatine kinase, actin, prohibitin, a T-cell receptor alpha chain, defensin-related cryptdin 5, and the intermediate filament proteins glial fibrillary acidic protein and vimentin. SPR, the most strongly up-regulated protein observed, controls production of tetrahydrobiopterin, an essential cofactor for the synthesis of many neurotransmitters including serotonin, making it a plausible and intriguing candidate protein for involvement in mood control and antidepressant drug action. SPR and the other proteins identified may represent links to molecular processes of importance to mood dysregulation and control, and their respective genes may be novel candidates for the study of antidepressant pharmacogenetics.

Depression, antidepressants, and plasma amyloid beta (Beta) peptides in those elderly who do not have cardiovascular disease

BACKGROUND

Low plasma amyloid-beta peptide 42 (Abeta42) is associated with depressive symptoms independently of cardiovascular disease (CVD) in the elderly. It is critical to investigate whether antidepressants modify this relationship.

METHODS

We evaluated 324 elders without CVD in a cross-sectional study. Depression was evaluated with the Center for Epidemiological Studies Depression (CES-D) scale. Antidepressants were documented. Plasma Abeta40 and Abeta42 were measured.

RESULTS

In the absence of CVD, those with depression had lower plasma Abeta42 (median: 13.7 vs. 18.8 pg/mL, p = .003) than those without. Depressed subjects on antidepressant treatment had a lower concentration of plasma Abeta40 (median: 97.8 vs. 133.5 pg/mL, p = .008), but not Abeta42, than those without the treatment. Multivariate logistic regression showed that antidepressant use did not influence the relationship between depression and low plasma Abeta42 (odds ratio = .55; 95% CI = .33, .90; p = .02) after adjusting for confounders, but its use interacted with plasma Abeta40 in the model.

CONCLUSIONS

Lower concentration of plasma Abeta42 is associated with depression in the absence of CVD that is not related to the antidepressant use by those subjects. Prospective studies are needed to determine whether depression associated with low plasma Abeta42 predicts the onset of Alzheimer's disease.

The cognitive neuropsychology of depression in the elderly

BACKGROUND

The cognitive impairment of older depressed patients with late- as opposed to early-onset illness may show important differences, in that patients with early onset may suffer predominantly from impaired episodic memory, and those with late onset mainly from reductions of executive function and processing speed.

METHOD

We searched Medline and EMBASE as well as individual papers' reference lists for relevant publications, recording comparisons in neuropsychological test results between early-onset depression (EOD), late-onset depression (LOD) and healthy volunteers. Effect sizes are presented for cognitive domains, such as executive function, processing speed, episodic memory, semantic memory and mental state examination.

RESULTS

Patients with LOD showed greater reductions in processing speed and executive function than patients with EOD and controls. Both patient groups showed reduced function in all domains, except mental state, compared with controls.

CONCLUSION

Pronounced executive deficits are typical of the late-onset patients described in published studies, while episodic memory impairment is not specific to early-onset illness. Possible reasons and confounders are discussed.

Causality of stem cell based neurogenesis and depression--to be or not to be, is that the question?

Mood disorders compose a considerable portion of the worldwide prevailing diseases with high suicide rates and urgent demand for novel therapeutic interventions as efficacious treatment is still lacking. Depression is thought to feature distinct morphological correlatives in the brain and has recently been linked to adult neurogenesis (NG) in the hippocampal formation. Numerous findings give rise to the hypothesis that depression and declining NG in the hippocampus may be causally connected. This implies that depressive symptoms could originate from impairments in NG and, vice versa, that improved NG could mediate antidepressant action and alleviate symptoms. Thus, great hopes rest on the question whether the observed increase in NG following antidepression treatment may have the potential to become a novel drug target and specific mechanism in the development of the next generation of antidepressants that specifically involves targeting of neuropoetic factors in addition to their "traditional" effects as modulators of synaptic transmission. Along the still hypothetical association of depression and NG, however, several controversies and unresolved questions exist with respect to the presently available data and interpretation. This article highlights and summarizes some of the most pressing issues and identifies the crucial ones that await urgent clarification and resolving. Without their reliable answering, the fascinating notion of a neurogenic basis for depression will remain to be greatly speculative.

The role of neurotrophic factors in adult hippocampal neurogenesis, antidepressant treatments and animal models of depressive-like behavior

Major depressive disorder (MDD) is characterized by structural and neurochemical changes in limbic structures, including the hippocampus, that regulate mood and cognitive functions. Hippocampal atrophy is observed in patients with depression and this effect is blocked or reversed by antidepressant treatments. Brain-derived neurotrophic factor and other neurotrophic/growth factors are decreased in postmortem hippocampal tissue from suicide victims, which suggests that altered trophic support could contribute to the pathophysiology of MDD. Preclinical studies demonstrate that exposure to stress leads to atrophy and cell loss in the hippocampus as well as decreased expression of neurotrophic/growth factors, and that antidepressant administration reverses or blocks the effects of stress. Accumulating evidence suggests that altered neurogenesis in the adult hippocampus mediates the action of antidepressants. Chronic antidepressant administration upregulates neurogenesis in the adult hippocampus and this cellular response is required for the effects of antidepressants in certain animal models of depression. Here, we review cellular (e.g. adult neurogenesis) and behavioral studies that support the neurotrophic/neurogenic hypothesis of depression and antidepressant action. Aberrant regulation of neuronal plasticity, including neurogenesis, in the hippocampus and other limbic nuclei may result in maladaptive changes in neural networks that underlie the pathophysiology of MDD.

ApoE4 allele is associated with late-life depression: a population-based study

OBJECTIVE

This study aimed to clarify the relationship between the epsilon4 allele and late-life depression, taking into account lipid profile, vascular diseases, and sociodemographics.

METHODS

Using a multilevel stratified random sampling strategy, a total of 500 subjects aged 65 to 74 years were recruited for this cross-sectional study from the official household records of an entire county in southern Taiwan. Depressive symptoms were assessed by the Taiwanese Depression Questionnaire (TDQ). Cognitive function was assessed by the Short Portable Mental Status Questionnaire. Blood samples were collected for the determination of the apolipoprotein E (ApoE) polymorphism and the lipid profile.

RESULTS

A total of 283 subjects (58.7% male, with a mean age of 69.2 +/- 2.7 years) completed all questionnaires and collection of blood samples. Using the chi(2) test, the overall difference for frequency of the presence of the epsilon4 allele was significant among the severe group (TDQ score >18), moderate group (TDQ score 9-18), and mild group (TDQ score <9). The proportion of history of heart disease was significantly higher in the severe group than in the mild or moderate group. Kruskal-Wallis statistics revealed that the mean total and low-density lipoprotein cholesterol levels were significantly higher in the severe group than in the moderate or mild group. With our two-level four-class latent class regression model, the presence of the epsilon4 allele was significantly associated with the severely depressed group as compared to the nondepressed group, adjusting for vascular diseases and lipid profile.

CONCLUSION

The ApoE epsilon4 allele may be correlated with severe depression in the elderly through ways other than the "vascular depression" hypothesis.

Allelic differences in the brain-derived neurotrophic factor Val66Met polymorphism in late-life depression

OBJECTIVE

The Val66Met polymorphism of the brain-derived neurotrophic factor gene is associated with cognitive and neuroimaging changes. The authors examined the relationship between this polymorphism and depression in an elderly sample, hypothesizing that the Met66 allele would be associated with late-life depression.

METHODS

A total of 245 elderly depressed white subjects and 94 elderly comparison white subjects completed clinical assessments and provided a blood sample for genotyping. Subjects were dichotomized as either homozygous for the Val66 allele or Met66 allele carriers. Gene frequencies were compared between groups, with separate analyses examining for differences in gene frequencies based on age of depression onset, family history, and depression history. Logistic regression models examined the relationship between genotype and depression after controlling for age, sex, and race.

RESULTS

Depressed subjects were more likely to be Met66 allele carriers than were comparison subjects (38.8% versus 24.4%; chi(2) = 6.13, 1 df, p = 0.0133). This relationship remained significant after controlling for covariates (Wald chi(2) = 5.10, 1 df, p = 0.024; odds ratio: 1.92, 95% confidence interval: 1.09-3.38). There were no significant relationships between genotype and age of onset, number of episodes, or family history of depression.

CONCLUSION

Met66 allele carriers have almost double the odds of having geriatric depression than do Val66 allele homozygotes. This polymorphism was unrelated to other clinical characteristics of depression in later life.

Translational research in late-life mood disorders: implications for future intervention and prevention research

Clinical and epidemiological studies have consistently observed the heterogeneous symptomatology and course of geriatric depression. Given the importance of genetic and environmental risk factors, aging processes, neurodegenerative and cerebrovascular disease processes, and medical comorbidity, the integration of basic and clinical neuroscience research approaches is critical for the understanding of the variability in illness course, as well as the development of prevention and intervention strategies that are more effective. These considerations were the impetus for a workshop, sponsored by the Geriatrics Research Branch in the Division of Adult Translational Research and Treatment Development of the National Institute of Mental Health that was held on September 7-8, 2005. The primary goal of the workshop was to bring together investigators in geriatric psychiatry research with researchers in specific topic areas outside of geriatric mental health to identify priority areas to advance translational research in geriatric depression. As described in this report, the workshop focused on a discussion of the development and application of integrative approaches combining genetics and neuroimaging methods to understand such complex issues as treatment response variability, the role of medical comorbidity in depression, and the potential overlap between depression and dementia. Future directions for integrative research were identified. Understanding the nature of geriatric depression requires the application of translational research and interdisciplinary research approaches. Geriatric depression could serve as a model for translational research integrating basic and clinical neuroscience approaches that would have implications for the study of other neuropsychiatric disorders.

Hippocampal volume and mood disorders after traumatic brain injury

BACKGROUND

Recent evidence from clinical studies and animal models of traumatic brain injury (TBI) suggest that neuronal and glial loss might progress after the initial insult in selectively vulnerable regions of the brain such as the hippocampus. There is also evidence that hippocampal dysfunction plays a role in the pathogenesis of mood disorders. We examined the relationship between hippocampal damage and mood disorders after TBI and the effect of hippocampal atrophy on the outcome of TBI patients.

METHODS

The study group consisted of 37 patients with closed head injury who were evaluated at baseline and at 3, 6, and 12 months after trauma. Psychiatric diagnosis was made with a structured clinical interview and DSM-IV criteria. Quantitative magnetic resonance imaging scans were obtained at 3-months follow-up.

RESULTS

Patients with moderate to severe head injury had significantly lower hippocampal volumes than patients with mild TBI. Patients who developed mood disorders had significantly lower hippocampal volumes than patients without mood disturbance. Furthermore, there was a significant interaction between mood disorders diagnosis and severity of TBI, by which patients with moderate to severe TBI who developed mood disorders had significantly smaller hippocampal volumes than patients with equivalent severe TBI who did not develop mood disturbance. Finally, reduced hippocampal volumes were associated with poor vocational outcome at 1-year follow-up.

CONCLUSIONS

Our findings are consistent with a "double-hit" mechanism by which neural and glial elements already affected by trauma are further compromised by the functional changes associated with mood disorders (e.g., the neurotoxic effects of increased levels of cortisol or excitotoxic damage resulting from overactivation of glutaminergic pathways). Finally, patients with greater hippocampal damage were less likely to return to a productive life 1 year after trauma.

Modulation of stress consequences by hippocampal monoaminergic, glutamatergic and nitrergic neurotransmitter systems

Several findings relate the hippocampal formation to the behavioural consequences of stress. It contains a high concentration of corticoid receptors and undergoes plastic modifications, including decreased neurogenesis and cellular remodelling, following stress exposure. Various major neurotransmitter systems in the hippocampus are involved in these effects. Serotonin (5-HT) seems to exert a protective role in the hippocampus and attenuates the behavioural consequences of stress by activating 5-HT1A receptors in this structure. These effects may mediate the therapeutic actions of several antidepressants. The role of noradrenaline is less clear and possibly depends on the specific hippocampal region (dorsal vs. ventral). The deleterious modifications induced in the hippocampus by stress might involve a decrease in neurotrophic factors such as brain derived neurotrophic factor (BDNF) following glutamate N-methyl-D-aspartate (NMDA) receptor activation. In addition to glutamate, nitric oxide (NO) could also be related to these effects. Systemic and intra-hippocampal administration of nitric oxide synthase (NOS) inhibitors attenuates stress-induced behavioural consequences. The challenge for the future will be to integrate results related to these different neurotransmitter systems in a unifying theory about the role of the hippocampus in mood regulation, depressive disorder and antidepressant effects.

Patterns of gene expression in the limbic system of suicides with and without major depression

The limbic system has consistently been associated with the control of emotions and with mood disorders. The goal of this study was to identify new molecular targets associated with suicide and with major depression using oligonucleotide microarrays in the limbic system (amygdala, hippocampus, anterior cingulate gryus (BA24) and posterior cingulate gyrus (BA29)). A total of 39 subjects were included in this study. They were all male subjects and comprised 26 suicides (depressed suicides=18, non depressed suicides=8) and 13 matched controls. Brain gene expression analysis was carried out on human brain samples using the Affymetrix HG U133 chip set. Differential expression in each of the limbic regions showed group-specific patterns of expression, supporting particular neurobiological mechanisms implicated in suicide and depression. Confirmation of genes selected based on their significance and the interest of their function with reverse transcriptase-polymerase chain reaction showed consistently correlated signals with the results obtained in the microarray analysis. Gene ontology analysis with differentially expressed genes revealed an overrepresentation of transcription and metabolism-related genes in the hippocampus and amygdala, whereas differentially expressed genes in BA24 and BA29 were more generally related to RNA-binding, regulation of enzymatic activity and protein metabolism. Limbic expression patterns were most extensively altered in the hippocampus, where processes related to major depression were associated with altered expression of factors involved with transcription and cellular metabolism. Additionally, our results confirm previous evidence pointing to global alteration of gabaergic neurotransmission in suicide and major depression, offering new avenues in the study and possibly treatment of such complex disorders. Overall, these data suggest that specific patterns of expression in the limbic system contribute to the etiology of depression and suicidal behaviors and highlight the role of the hippocampus in major depression.

Depression is associated with low plasma Abeta42 independently of cardiovascular disease in the homebound elderly

BACKGROUND

Depression often precedes the onset of Alzheimer's disease (AD) before the appearance of cognitive symptoms. Plasma Amyloid-beta peptide 42 (Abeta42) declines before and soon after the onset of AD, yet the relationship between plasma Abeta42 and depression is unclear.

METHODS

We used 515 homebound elders aged 60 and older in a population-based, cross-sectional study to investigate associations between plasma Abeta levels and depression with and without cardiovascular co-morbidities. Depression was evaluated by using the Center for Epidemiological Studies Depression (CES-D) scale. Plasma Abeta40 and Abeta42 were measured.

RESULTS

The elderly with depression had lower plasma Abeta42 (median: 15.3 vs. 18.9, p = 0.008) than those without depression. The CES-D score was inversely associated with plasma Abeta42 (p = 0.001) in subjects with no cardiovascular disease (CVD); however, in the presence of CVD, this association did not exist. Low plasma Abeta42 (OR = 0.41, p = 0.007) and the presence of CVD (OR = 1.84, p = 0.005) were independently associated with depression after adjusting for the confounders of age, stroke and apolipoprotein E4.

CONCLUSIONS

Depressive symptoms are associated with low plasma Abeta42 independently of CVD. Prospective studies are needed to determine whether depression associated with low plasma Abeta42 is a separate depression subtype that could predict the onset of AD.

Cerebral volume measurements and subcortical white matter lesions and short-term treatment response in late life depression

BACKGROUND

Late life depression is associated with volumetric reductions of gray matter and increased prevalence of subcortical white matter lesions. Previous studies have shown a poorer treatment outcome in those with more severe structural brain abnormalities. In this study, quantitative and semi-quantitative magnetic resonance imaging (MRI) measures were studied in relation to response to a 12-week controlled antidepressant monotherapy trial.

METHODS

MRI (1.5 T) brain scans of 42 elderly inpatients with major depression, of which 23 were non-responder to a controlled 12-week antidepressant monotherapy trial, were acquired. In addition, clinical outcome was assessed after a one year period. Measures were volumes of global cerebral and subcortical structures.

RESULTS

After controlling for confounding, no differences were found between non-responders and responders after 12 weeks and after one year in volumes of cerebral gray and white matter, orbitofrontal cortex, hippocampus and white matter lesions.

CONCLUSIONS

Structural brain measures associated with late life depression may not be related to short-term treatment response.

Treating depression in the medically ill

Depression frequently is comorbid with a variety of medical illnesses; individuals who have such comorbidities may have increased morbidity and lower functional status. Usual antidepressant treatments can be effective in depressed patients who have comorbid medical illness. These patients, however, experience lower rates of recovery and remission of depressive symptoms and higher rates of relapse during follow-up than seen in patients who have MDD with no medical comorbidity. Comorbid medical illness therefore is a marker of treatment resistance in MDD. Collaborative treatments combining antidepressants, psychotherapy, education, and case management may be effective and could overcome the risk of treatment resistance. Two clinical strategies seem warranted in light of the studies presented here: (1) an increased index of suspicion for depression in medically ill patients, and (2) more intensive antidepressant treatment in depressed patients who have medical comorbidity.

A splice site polymorphism in the G-protein β subunit influences antidepressant efficacy in depression

OBJECTIVE

Recent evidence suggests that signalling cascades located downstream of monoamine receptors are altered following antidepressant treatment. Our objective was to investigate whether genetic polymorphisms in genes involved in these signalling cascades influenced antidepressant efficacy.

METHODS

Polymorphisms in the G-protein beta subunit GNB3, the cAMP response element binding protein 1 gene (CREB1), the brain derived neurotrophic factor (BDNF) and CREB binding protein (CREBBP) were studied in well characterised unipolar (n=166) and early onset (n=102) depressive populations and correlated with treatment response.

RESULTS

The GNB3 C825T polymorphism, which results in a 41 amino acid deletion, was significantly associated with lack of remission (OR=0.18, P=0.02) and lack of response (OR=0.26, P=0.03) following 2nd switch treatment. A cytosine deletion 16 base pairs from the start of exon 8 in CREB1 was found more frequently in remitters and responders to 2nd switch antidepressant drug therapy, although these differences failed to reach significance. Polymorphisms detected BDNF (G196A) and CREBBP (T651 C) did not appear to influence antidepressant response.

CONCLUSIONS

These results suggest that inheritance of the GNB3C825T allele may significantly influence antidepressant response and emphasises the potential importance of polymorphisms in genes in signalling cascades activated by commonly prescribed antidepressants.

Tianeptine increases brain-derived neurotrophic factor expression in the rat amygdala

Chronic restraint stress affects hippocampal and amygdalar synaptic plasticity as determined by electrophysiological, morphological and behavioral measures, changes that are inhibited by some but not all antidepressants. The efficacy of some classes of antidepressants is proposed to involve increased phosphorylation of cAMP response element binding protein (CREB), leading to increased expression of neurotrophic factors, such as brain-derived neurotrophic factor (BDNF). Conversely, some studies suggest that acute and chronic stress downregulate BDNF expression and activity. Accordingly, the aim of the current study was to examine total and phosphorylated CREB (pCREB), as well as BDNF mRNA and protein levels in the hippocampus and amygdala of rats subjected to chronic restraint stress in the presence and absence of the antidepressant tianeptine. In the hippocampus, chronic restraint stress increased pCREB levels without affecting BDNF mRNA or protein expression. Tianeptine administration had no effect upon these measures in the hippocampus. In the amygdala, BDNF mRNA expression was not modulated in chronic restraint stress rats given saline in spite of increased pCREB levels. Conversely, BDNF mRNA levels were increased in the amygdala of chronic restraint stress/tianeptine rats in the absence of changes in pCREB levels when compared to non-stressed controls. Amygdalar BDNF protein increased while pCREB levels decreased in tianeptine-treated rats irrespective of stress conditions. Collectively, these results demonstrate that tianeptine concomitantly decreases pCREB while increasing BDNF expression in the rat amygdala, increases in neurotrophic factor expression that may participate in the enhancement of amygdalar synaptic plasticity mediated by tianeptine.

Inflammation and depression: is there a causal connection with dementia?

Epidemiological studies show that there is a correlation between chronic depression and the likelihood of dementia in later life. There is evidence that inflammatory changes in the brain are pathological features of both depression and dementia. This suggests that an increase in inflammation-induced apoptosis, together with a reduction in the synthesis of neurotrophic factors caused by a rise in brain glucocorticoids, may play a role in the pathology of these disorders. A reduction in the neuroprotective components of the kynurenine pathway, such as kynurenic acid, and an increase in the neurodegenerative components, 3- hydroxykynurenine and quinolinic acid, contribute to the pathological changes. Such changes are postulated to cause neuronal damage and thereby predispose chronically depressed patients to dementia.

New paradigm for treating recurrent depression: from symptom control to managing enduring vulnerabilities

Optimal management of depression remains a long-term challenge. Long-term maintenance treatment with antidepressants has been shown to be effective for preventing or delaying recurrence for many patients with a history of previous multiple episodes. However, aside from a history of multiple recurrences, it remains difficult to identify patients who are most likely to experience recurrence and when. Thus we do not really know who might particularly benefit from maintenance therapy and what type may be efficacious. In patients with depression, research has shown there are structural and functional alterations in the brain, particularly in patients with recurrent or chronic depression. These changes have been generally viewed to be consequences of the disease, which are seen to worsen with a longer duration of untreated illness and with a greater number of depressive episodes. However, these neurobiological characteristics may also represent risk factors or vulnerabilities that predispose some patients to chronic or recurrent depression. Additional research has demonstrated that antidepressant treatment may reduce or modulate these functional and structural changes, suggesting that long-term treatment may, in fact, benefit patients not only by controlling symptoms but also by managing these underlying vulnerabilities. A new treatment paradigm, which focuses on identifying patients with risk factors and managing the disease process rather than suppression of symptoms, is needed for recurrent depression.

Differences in brain volumes among males and female hormone-therapy users and nonusers

Numerous studies have shown gender differences in the brain volumes of elderly adults. Some evidence shows that higher estrogen levels may be neuroprotective, suggesting that hormone therapy (HT) may in part be responsible for these gender differences; however, few studies have examined the relation between HT and brain volumes. Brain volumes of caudate, putamen, hippocampus, gray matter, white matter, white-matter lesions, and cerebrospinal fluid were measured on magnetic resonance imaging scans. A comprehensive neuropsychological battery was administered. Women were separated into two groups based on HT use, and we used multiple regression analyses to compare these groups with one another and with men. Results of brain-volume measurements showed that HT users had significantly less gray matter and more cerebrospinal fluid than nonusers. Results of the neuropsychological testing showed that HT users performed better on the Shipley Vocabulary Test than males did.

Aging, gender, and the elderly adult brain: an examination of analytical strategies

We sought to examine the relations between age, gender and brain volumes in an elderly population; we also sought to examine ways of measuring these relations. Three sets of analyses were used: correlational analyses, in which correlations between independent variables and brain volumes were calculated without correction for intracranial volume (ICV); covariational analyses, in which ICV was used as a covariate in regression equations; and ratio analyses, in which the dependent variable was the ratio of brain volume to ICV. These analyses yielded similar results, except that (as expected) adjusting for ICV altered estimates of gender differences. Analyses of age showed decreases in left caudate, putamen, and right hippocampus and an increase in CSF, a result generally in accord with previous findings. However, we also found a significant decrease of white-matter volumes and no significant decrease in total gray-matter volumes. Correlational analyses showed that men did not always have larger volumes despite their larger head size; women generally had larger volumes after adjusting for ICV. We found no age-gender interactions.

Structural neuroimaging research methods in geriatric depression

Geriatric depression consists of complex and heterogeneous behaviors unlikely to be caused by a single brain lesion. However, there is evidence that abnormalities in specific brain structures and their interconnections confer vulnerability to the development of late-life depression. Structural magnetic resonance imaging methods can be used to identify and quantify brain abnormalities predisposing to geriatric depression and in prediction of treatment response. This article reviews several techniques, including morphometric approaches, study of white matter hyperintensities, diffusion tensor imaging, magnetization transfer imaging, t2 relaxography, and spectroscopy, that have been used to examine these brain abnormalities with a focus on the type of information obtained by each method as well as each method's limitations. The authors argue that the available methods provide complementary information and that, when combined judiciously, can increase the knowledge gained from neuroimaging findings and conceptually advance the field of geriatric depression.

Chemotherapy and Cognition: Effects, Potential Mechanisms, and Management

The development of novel chemotherapeutic agents and advances in treatment technique have improved survival for patients diagnosed with some forms of cancer, but treatments are not always site specific and may place normal tissues at risk. The central nervous system (CNS) is susceptible to treatment effects and complaints of memory loss and generalized cognitive decline are common among cancer patients. Despite the frequency of subjective patient complaints, studies evaluating the cognitive abilities of patients have inconsistently reported chemotherapy-related declines. On careful review of the literature, discrepant findings across studies (some documenting chemotherapy-related cognitive declines and others failing to detect such changes) may be attributed to differences in methodology. Most studies have been retrospective in design, omit pretreatment assessment of function, use small or heterogeneous samples, use inappropriate measures to assess cognition, and fail to incorporate control subjects. Though rare to date, prospective, randomized, longitudinal studies that incorporate pretreatment comprehensive neuropsychological assessment are necessary to define the severity and pattern of treatment-related change. Building on a foundation of solid science, future studies may identify subgroups of patients susceptible to significant chemotherapy-related cognitive decline. Once these groups are identified and the mechanisms underlying the decline are elucidated, attention may be turned to the development of treatments that may optimize cognitive function and improve patient quality of life.

Impairment of the spatial learning and memory induced by learned helplessness and chronic mild stress

Increasing evidences indicate the concurrence and interrelationship of depression and cognitive impairments. The present study was undertaken to investigate the effects of two depressive animal models, learned helplessness (LH) and chronic mild stress (CMS), on the cognitive functions of mice in the Morris water maze task. Our results demonstrated that both LH and CMS significantly decreased the cognitive performance of stressed mice in the water maze task. The escaping latency to the platform was prolonged and the probe test percentage in the platform quadrant was reduced. These two models also increased the plasma corticosterone concentration and decreased the brain derived neurotrophic factor (BDNF) and cAMP-response element-biding protein (CREB) messenger ribonucleic acid (mRNA) levels in hippocampus, which might cause the spatial cognition deficits. Repeated treatment with antidepressant drugs, imipramine (Imi) and fluoxetine (Flu), significantly reduced the plasma corticosterone concentration and enhanced the BDNF and CREB levels. Furthermore, antidepressant treated animals showed an ameliorated cognitive performance compared with the vehicle treated stressed animals. These data suggest that both LH and CMS impair the spatial cognitive function and repeated treatment with antidepressant drugs decreases the prevalence of cognitive impairments induced by these two animal models. Those might in part be attributed to the reduced plasma corticosterone and enhanced hippocampal BDNF and CREB expressions. This study provided a better understanding of molecular mechanisms underlying interactions of depression and cognitive impairments, although animal models used in this study can mimic only some aspects of depression or cognition of human.

Hippocampal volume is associated with physician-reported acute cognitive deficits after electroconvulsive therapy

Predicting memory problems in older depressed patients receiving electroconvulsive therapy (ECT) is difficult. In this study, hippocampal volume and acute memory outcomes were examined in 15 patients following an index course of ECT. Smaller hippocampal volume was associated with poorer ECT-related memory outcomes. These results add to a growing literature on memory, ECT, and the hippocampus. Although the findings are significant, the sample size in the study is small, so future studies with more complex modeling of key variables that may influence memory are warranted.

Volumetric brain imaging studies in the elderly with mood disorders

Volumetric neuroimaging studies of the elderly with affective disorders provide important insights into the underlying physiology of the illnesses. Advantages of studying the elderly include the ability to make various assessments and obtain a history differentiating subtypes of illness. However, challenges to studying the elderly include the heterogeneity of affective illnesses and confounds of medical comorbidity and medications. Volumetric assessments have provided important information in the neural mechanisms of mood regulation, especially in the overlap of cognitive disorders. This article reviews articles describing findings of volumetric analyses in elderly with unipolar depression and bipolar disorders, and compares and contrasts these findings with the larger volumetric research in affective disorders.

The dual origin hypothesis: An evolutionary brain-behavior framework for analyzing psychiatric disorders

According to the dual origin hypothesis, the cerebral cortex of higher mammals evolved from two primordial brain structures, the amygdala and hippocampal formation. This developmental process defines the orderly principles of cortical connectivity and gives rise to functionally distinct ventral and dorsal systems within the cerebrum. This paper reviews the basic features of the dual origin theory. This model is then applied to understanding symptom production in a number of psychiatric illnesses, with particular reference to recent structural and functional imaging studies. In this paper I propose that psychiatric symptoms can be conceptualized as arising from abnormal processing within dorsal (time-space-motility) or ventral (meaning-motivation) systems, or from a disturbance in the functional interaction/balance between them. Within this framework, one can identify symptom-specific correlations that cross-traditional diagnostic boundaries, as well as potential mechanisms that may explain biologically valid diagnostic entities. Integrating evolutionary, connectional and functional bases across multiple species, the dual origin hypothesis offers a powerful neural systems model to help organize our understanding of psychiatric illness, therein suggesting novel approaches to diagnosis, prevention and treatment.

Hippocampal neurogenesis: Opposing effects of stress and antidepressant treatment

The hippocampus is one of several limbic brain structures implicated in the pathophysiology and treatment of mood disorders. Preclinical and clinical studies demonstrate that stress and depression lead to reductions of the total volume of this structure and atrophy and loss of neurons in the adult hippocampus. One of the cellular mechanisms that could account for alterations of hippocampal structure as well as function is the regulation of adult neurogenesis. Stress exerts a profound effect on neurogenesis, leading to a rapid and prolonged decrease in the rate of cell proliferation in the adult hippocampus. In contrast, chronic antidepressant treatment up-regulates hippocampal neurogenesis, and could thereby block or reverse the atrophy and damage caused by stress. Recent studies also demonstrate that neurogenesis is required for the actions of antidepressants in behavioral models of depression. This review discusses the literature that has lead to a neurogenic hypothesis of depression and antidepressant action, as well as the molecular and cellular mechanisms that underlie the regulation of adult neurogenesis by stress and antidepressant treatment.

Major affective disorders and schizophrenia: a common molecular signature?

Psychiatric disorders, including affective disorders (AD) and schizophrenia (SZ) are among the most common disabling brain diseases in Western populations and result in high costs in terms of morbidity as well as mortality. Although their etiology and pathophysiology is largely unknown, family-, twin-, and adoption studies argue for a strong genetic determination of these disorders. These studies indicate that there is between 40 and 85% heritability for these disorders but point also to the importance of environmental factors. Therefore, any research strategy aiming at the identification of genes involved in the development of AD and SZ should account for the complex nature (multifactorial) of these disorders. During the last decade, molecular genetic studies have contributed a great deal to the identification of genetic factors involved in complex disorders. Here we provide a comprehensive review of the most promising genes for AD and SZ, and the methods and approaches that were used for their identification. Also, we discuss the current knowledge and hypotheses that have been formulated regarding the effect of variations on protein functioning as well as recent observations that point to common molecular mechanisms.

Volume deficits of subcortical nuclei in mood disorders A postmortem study

Structural changes in subcortical nuclei may underlie clinical symptoms of mood disorders. The goal was to determine whether macrostructural changes exist in brain areas assumed to be involved in regulation of mood and whether such changes differ between major depressive disorder and bipolar disorder. A case-control design was used to compare volumes of all major subcortical nuclei. Brains of patients with major depressive disorder (n = 9) or bipolar disorder (n = 11) or of individuals without a neuropsychiatric disorder (n = 22) were included. Exclusion criteria were a history of substance abuse or histological signs of neurodegenerative disorders. Volumes of the striato-pallidal nuclei, of the hypothalamus, thalamus, amygdala, hippocampus and basal limbic forebrain were determined in the right and left hemisphere by planimetry of 20 mum whole brain serial paraffin sections. Comparisons between patients with bipolar disorder, major depressive disorder and controls showed a significant (Lambda = 0.35, F(20,56) = 1.93, P = 0.028) overall difference in volumes of all investigated regions with strong effect sizes ( f > 0.40) contributed by the hypothalamus, external pallidum, putamen and thalamus. As compared to controls, a strong effect size (f > 0.40) was found in the bipolar group for smaller volumes of the hypothalamus, external pallidum, putamen and thalamus,whereas in patients with major depressive disorder a strong effect size was only found for a smaller volume of the external pallidum. In conclusion our data suggest that pathways presumably involved in mood regulation have structural pathology in affective disorders with more pronounced abnormalities in bipolar disorder.

Male elderly subthreshold depression patients have smaller volume of medial part of prefrontal cortex and precentral gyrus compared with age-matched normal subjects: a voxel-based morphometry

BACKGROUND

The brain morphological changes in subthreshold depression (sD) have not been clarified. We examined the structural difference in regional gray matter volume between community-dwelling elderly subjects with sD and age-matched nondepressed normal subjects by voxel-based morphometry (VBM) based on magnetic resonance imaging (MRI).

METHODS

Thirty-four community-dwelling elderly subjects with sD and 109 age-matched nondepressed normal subjects were studied by MRI. We defined subjects with sD as those who showed a Geriatric Depression Scale score of 15 or higher and a Mini Mental State Examination score of 22 or higher, and do not fulfill the criteria of major depressive disorder (MDD) in the Diagnostic and Statistical Manual for Mental Disorders IV. We collected brain magnetic resonance images of 34 subjects with sD and 109 age-matched normal subjects, and analyzed the difference in regional gray matter volume between these two groups by VBM.

RESULTS

Male subjects with sD had significantly smaller volumes of the medial part of the bilateral frontal lobes and the right precentral gyrus than normal male subjects.

LIMITATIONS

We have not clarified the discrepancy in the results of gender difference.

CONCLUSIONS

Our study revealed that even community-dwelling elderly male subjects with sD show bilateral prefrontal gray matter volume reduction, which was reported to be observed in elderly patients with MDD, although there is no significant volume reduction in the hippocampus, which was also reported to be observed in MDD. Our study may contribute to clarifying the mechanism underlying brain pathological changes in sD.

Automated segmentation of neuroanatomical structures in multispectral MR microscopy of the mouse brain

We present the automated segmentation of magnetic resonance microscopy (MRM) images of the C57BL/6J mouse brain into 21 neuroanatomical structures, including the ventricular system, corpus callosum, hippocampus, caudate putamen, inferior colliculus, internal capsule, globus pallidus, and substantia nigra. The segmentation algorithm operates on multispectral, three-dimensional (3D) MR data acquired at 90-microm isotropic resolution. Probabilistic information used in the segmentation is extracted from training datasets of T2-weighted, proton density-weighted, and diffusion-weighted acquisitions. Spatial information is employed in the form of prior probabilities of occurrence of a structure at a location (location priors) and the pairwise probabilities between structures (contextual priors). Validation using standard morphometry indices shows good consistency between automatically segmented and manually traced data. Results achieved in the mouse brain are comparable with those achieved in human brain studies using similar techniques. The segmentation algorithm shows excellent potential for routine morphological phenotyping of mouse models.