Hippocampal volume change in depression: late- and early-onset illness compared

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.

Regional gray matter changes are associated with cognitive deficits in remitted geriatric depression: an optimized voxel-based morphometry study

BACKGROUND

We aimed to investigate structural abnormalities in first-episode remitted geriatric depression (RGD) with optimized voxel-based morphometry (VBM) in closely matched patients and healthy control subjects and examine the relationship of performances on neuropsychological tests with regional gray matter volumes.

METHODS

Nineteen subjects with first-episode RGD and 16 well-matched healthy control subjects were recruited for this study, and neuropsychological tests and magnetic resonance imaging were conducted on the subjects. The differences in regional gray matter volume were determined between these two groups by optimized VBM.

RESULTS

The volumes of right superior frontal cortex, left postcentral cortex, and right middle temporal gyrus were significantly smaller in patients with RGD relative to healthy control subjects. However, patients with RGD had larger left cingulate gyrus volume compared with healthy control subjects. There was a significant negative correlation between left cingulate gyrus volume and Rey Auditory Verbal Learning Test delayed recall raw score in patients with RGD.

CONCLUSION

These results reveal that RGD is associated with gray matter changes of certain brain regions hypothesized to influence cognition and might thus be involved in the psychopathology and pathophysiology of cognitive impairment in RGD.

Neurogenesis in the aging brain

Neurogenesis, or the birth of new neural cells, was thought to occur only in the developing nervous system and a fixed neuronal population in the adult brain was believed to be necessary to maintain the functional stability of adult brain circuitry. However, recent studies have demonstrated that neurogenesis does indeed continue into and throughout adult life in discrete regions of the central nervous systems (CNS) of all mammals, including humans. Although neurogenesis may contribute to the ability of the adult brain to function normally and be induced in response to cerebral diseases for self-repair, this nevertheless declines with advancing age. Understanding the basic biology of neural stem cells and the molecular and cellular regulation mechanisms of neurogenesis in young and aged brain will allow us to modulate cell replacement processes in the adult brain for the maintenance of healthy brain tissues and for repair of disease states in the elderly.

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.

White matter integrity of the whole brain is disrupted in first-episode remitted geriatric depression

Previous studies have demonstrated lower-diffusion anisotropy within white matter in late-onset depression measured by diffusion tensor imaging, which provides information about brain white matter integrity. We have examined whether white matter is abnormal in first-episode remitted geriatric depression by using diffusion tensor imaging. Sixteen remitted geriatric depression patients and 14 well matched healthy controls underwent diffusion tensor-imaging scans of magnetic resonance imaging, which were analyzed by a rigorous voxel-based approach. We found that fractional anisotropy in white matter was lower in patients than in controls at the right superior frontal gyrus, left inferior frontal gyrus, left middle temporal gyrus, right inferior parietal lobule, right middle occipital gyrus, left lingual gyrus, right putamen and right caudate. These results suggested that the white matter integrity of the whole brain was disrupted in first-episode remitted geriatric depression, and that these abnormalities were perhaps involved in the psychopathology and pathophysiology of cognitive impairment in remitted geriatric depression.

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.

Clinicopathological findings of suicide in the elderly: three cases

The neuropathological correlates of suicide in older persons have received little research attention. Our recent study of elderly suicide victims from an Australian forensic medicine department (n = 143), unlike a previous case-control study, did not find an increased prevalence of Alzheimer's disease (AD) in older persons who committed suicide despite a history of dementia in 6.3%. Both studies were limited to the examination of AD-related pathology by the availability of tissue. We present clinicopathological data on three cases from our study for whom autopsy findings were available. These cases included: a community-dwelling male in his early eighties with dementia who was found to have multiple cortical and striatal lacunes and glial scars, small vessel cerebrovascular disease (SVD) and AD-related pathology; a community-dwelling male in his mid-seventies with depression and loss of concentration, with brainstem predominant Lewy body disease (LBD) and AD-related pathology; and a female nursing home resident in her nineties with a history of stroke and prior suicide attempts who was found to have infarcts and SVD in frontal regions. Neuropathological findings in elderly suicide victims may include multiple neurodegenerative pathologies. The burden and distribution of neurodegenerative diseases apart from AD, including SVD and LBD, should be assessed as possible pathophysiological factors contributing to late life suicide.

Depressive symptoms in adolescents: associations with white matter volume and marijuana use

BACKGROUND

Depressed mood has been associated with decreased white matter and reduced hippocampal volumes. However, the relationship between brain structure and mood may be unique among adolescents who use marijuana heavily. The goal of this study was to examine the relationship between white matter and hippocampal volumes and depressive symptoms among adolescent marijuana users and controls.

METHODS

Data were collected from marijuana users (n = 16) and demographically similar controls (n = 16) aged 16-18. Extensive exclusionary criteria included psychiatric and neurologic disorders, including major depression. Substance use, mood, and anatomical measures were collected after 28 days of monitored abstinence.

RESULTS

Marijuana (MJ) users demonstrated more depressive symptoms than controls (p < .05). MJ use (beta = .42, p < .005) and smaller white matter volume (beta = -.34, p < .03) each predicted higher levels of depressive symptoms on the Hamilton Depression Rating Scale. MJ use interacted with white matter volume (beta = -.55, p < .03) in predicting depression scores on the Beck Depression Inventory: among MJ users, but not controls, white matter volume was negatively associated with depressive symptoms.

CONCLUSIONS

Marijuana use and white matter volume were additive and interactive in predicting depressive symptoms among adolescents. Subtle neurodevelopmental white matter abnormalities may disrupt the connections between areas involved in mood regulation.

Hippocampal volume and subcortical white matter lesions in late life depression: comparison of early and late onset depression

BACKGROUND

Reduced hippocampal volume and increased prevalence of subcortical white matter lesions are associated with both recurrent early onset depression (EOD) and late onset depression (LOD). It is not clear whether these two factors differentially affect the age of onset of first depression. Therefore, we wished to investigate the relationship between age of first depression onset and hippocampal volume, with adjustment for subcortical white matter lesions.

METHODS

MRI brain scans were used to compare hippocampal volumes and white matter lesions between age matched female patients (>60 years) with recurrent EOD and LOD and healthy controls.

RESULTS

When comparing the three groups and adjusting for age, the Mini-Mental State Examination score, total brain volume and total hippocampal volume were significantly smaller in patients with EOD compared with controls (5.6 vs 6.1 ml; p = 0.04). The prevalence of larger subcortical white matter lesions was higher in patients with LOD compared with patients with EOD (47% vs 8%; p = 0.002). Patients with LOD did not differ in hippocampal volume from patients with EOD or from controls.

CONCLUSIONS

In late life depression, age of first depression onset may distinguish between different independent neuropathological mechanisms. A small hippocampus volume may be a neuroanatomical marker of EOD depression and larger subcortical white matter lesions could be an intermediate between cerebrovascular disease and LOD.

The relationship between cytokines and pain/depression: A review and current status

Cytokines are small protein molecules secreted in response to immune stimuli. Recent research has outlined important roles for proinflammatory cytokines in the cascade of normal physiologic responses to environmental stresses, encompassing so-called sickness behavior that is thought to be an adaptive response to infection and other illnesses. Cytokines are involved in signaling that activates central nervous system glial cells. This activation is part of a poorly understood interaction between immune challenge or injury and host that can lead to the development or facilitation of persistent mood symptoms or pathologic pain. This article reviews evidence that may enhance our understanding of how pathologic symptoms, such as mood disorders and neuropathic pain, may emerge from proinflammatory cytokine activation. Possible conceptualizations of these illnesses and potential treatment implications are explored.

Transformation of arbitrary distributions to the normal distribution with application to EEG test-retest reliability

Many variables in the social, physical, and biosciences, including neuroscience, are non-normally distributed. To improve the statistical properties of such data, or to allow parametric testing, logarithmic or logit transformations are often used. Box-Cox transformations or ad hoc methods are sometimes used for parameters for which no transformation is known to approximate normality. However, these methods do not always give good agreement with the Gaussian. A transformation is discussed that maps probability distributions as closely as possible to the normal distribution, with exact agreement for continuous distributions. To illustrate, the transformation is applied to a theoretical distribution, and to quantitative electroencephalographic (qEEG) measures from repeat recordings of 32 subjects which are highly non-normal. Agreement with the Gaussian was better than using logarithmic, logit, or Box-Cox transformations. Since normal data have previously been shown to have better test-retest reliability than non-normal data under fairly general circumstances, the implications of our transformation for the test-retest reliability of parameters were investigated. Reliability was shown to improve with the transformation, where the improvement was comparable to that using Box-Cox. An advantage of the general transformation is that it does not require laborious optimization over a range of parameters or a case-specific choice of form.

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.

Prognosis of late life depression: a three-year cohort study of outcome and potential predictors

BACKGROUND

Late-onset depression (LOD) has a poor prognosis which may be worsened by the presence of cerebrovascular disease. Few studies have explored prospectively the influence of vascular risk factors on longer term prognosis.

METHODS

The original study involved 50 patients with LOD and 35 healthy age matched controls. Follow-up was at three years. Baseline measures included clinical, neuroradiological and neuropsychological variables. Outcome was assessed by mortality, progression to dementia and clinical course of depressive disorder.

RESULTS

Sixty-two (73%) of the original cohort agreed to be re-interviewed. Seven participants had died (all from the depressed group) and six developed dementia, all but one from the depressed group. Vascular dementia predominated (although not significantly so) among those with dementia at follow-up. For 28 depressed patients with complete follow-up data (56% of the original sample), poor outcome was predicted by lower High Density Lipoprotein (HDL), raised Erythrocyte Sedimentation Rate (ESR) and a higher score on the Hachinski Index scale and one test of immediate memory. Initial response to treatment was not associated with later outcome.

CONCLUSION

Late-onset depressive disorder is associated with a high rate of mortality and possibly dementia. Biochemical and inflammatory markers may be important in prognosis and their role should be confirmed in future studies.

Frontal white matter anisotropy and symptom severity of late-life depression: a magnetic resonance diffusion tensor imaging study

OBJECTIVES

To investigate the disruption of neural circuits in the frontal lobes and limbic structures in late-life depressed patients compared with healthy controls, and to examine the correlation between the degree of microstructural abnormalities of white matter and clinical symptom severity in late-life depression.

METHODS

Thirteen patients with late-life depression and matched control subjects underwent diffusion tensor imaging. Fractional anisotropy (FA), an index of the integrity of white matter tracts, was determined in the white matter of frontal, temporal, and occipital brain regions and the corpus callosum.

RESULTS

A significant reduction was found in white matter FA values of widespread regions of the frontal and temporal lobes of depressed patients. Also, there was some evidence suggesting that white matter FA values of the inferior frontal brain region are inversely related to severity of depression.

CONCLUSIONS

These results suggest the possible loss of integrity within frontal and temporal white matter fibre tracts and implicate the orbitofrontal circuit in symptom severity in late-life depression.

An update on regional brain volume differences associated with mood disorders

PURPOSE OF REVIEW

Structural brain changes are apparent in some magnetic resonance imaging studies of patients with mood disorders, but results are inconsistent. The focus of this review is to examine whether there are demographic or clinical characteristics of people with mood disorders that are associated with regional brain volume changes. A systematic search of the literature in English, from January 2004 to July 2005, was performed on MEDLINE. References cited in all reports were searched iteratively to identify missing studies.

RECENT FINDINGS

Recent studies have focused on factors that might help to reconcile the divergent reports of regional brain volume changes in major depressive disorder and bipolar disorder. Small hippocampal volumes are apparent in patients with recurrent major depressive disorder, but not generally reported early in the course of adult onset depression. Small hippocampal volumes may be apparent in patients with childhood onset illness. Small hippocampal volumes are infrequently reported in bipolar disorder, but studies to date have not accounted for illness history or treatment status. Changes in amygdala volumes are inconsistently reported in patients with major depressive disorder or bipolar disorder. There are relatively fewer reports of other brain regions, including the areas of the frontal cortex and striatum. An extensive preclinical literature suggests that various psychotropic medications may have neurotrophic and neuroprotective effects, making documentation of treatment history essential.

SUMMARY

Patients' age, sex, age at onset of disease, course of illness and treatment status may affect the detection of regional brain volume changes in people with mood disorders.

Stress and depression-induced immune dysfunction: implications for the development and progression of cancer

The persistent activation of the hypothalamic-pituitary-adrenal axis and the sympathetic-adrenal-medullary axes in chronic stress response and in depression impairs the immune response and contributes to the development and progression of some types of cancer. This overview presents results from experimental animal models, human studies, and clinical evidence that various cellular and molecular immunological parameters are compromised in chronic stress and depression. At the cellular level, stressed and depressed patients had overall leukocytosis, high concentrations of circulating neutrophils, reduced mitogen-stimulated lymphocyte proliferation and neutrophil phagocytosis. At the molecular level, high levels of serum basal cortisol, acute phase proteins, specific antibodies against herpes simplex virus type 1 and Epstein Barr virus, plasma concentration of interleukins IL-1, IL-6, and TNF-alpha, and a shift in the balance of Th1 and Th2 immune response were observed. Both stress and depression were associated with the decreased cytotoxic T-cell and natural killer cell activities affecting the processes of the immune surveillance of tumours, and the events that modulate the development and the accumulation of somatic mutations and genomic instability. DNA damage, growth and angiogenic factors, proteases, matrix metalloproteinases, and reactive oxygen species were also related to the chronic stress response and depression. Behavioural strategies, psychological, and psychopharmacotherapeutic interventions that enhance effective coping and reduce affective distress showed beneficial effects in cancer patients. A better understanding of the bidirectional communication between the neuroendocrine and immune systems could contribute to novel clinical and treatment strategies in oncology.

Nutrition and geriatric psychiatry: a neglected field

PURPOSE OF REVIEW

Nutritional issues have received little attention in geriatric psychiatry research. This review focuses on literature published in 2003 and 2004 on nutritional factors in mental illness in the elderly and proposes directions for future research.

RECENT FINDINGS

There has been more research on the role of micronutrients in psychiatric disorders of older adults but studies examining nutritional state in this population are lacking. The former research suggests associations between low folic acid/vitamin B12 status and depression in older adults whereas evidence for other micronutrients is still tentative. In the latter work, there is only one study that examines malnutrition in psychogeriatric patients despite the availability of well-validated screening tools for assessing nutritional state in the elderly and the known impact of undernutrition in ageing and the development of frailty. The role of obesity in ageing is also relevant especially as more people with schizophrenia live longer, although the current evidence in the non-mentally ill elderly suggests that being overweight may have protective effects in the elderly.

SUMMARY

Malnutrition is likely to have considerable impact on the mental and physical state of the elderly.

Neurological findings in late-onset depressive disorder: comparison of individuals with and without depression

BACKGROUND

Organic factors are thought to be important in late-life depressive disorder but there have been few studies specifically of neurological signs.

AIMS

To compare neurological signs in a group of patients with late-onset depression and in healthy controls.

METHOD

A case-control study comparing 50 patients with depression and 35 controls on three measures of central nervous system (CNS) signs: a structured CNS examination, the Neurological Evaluation Scale (NES) and the Webster rating scale for parkinsonism.

RESULTS

After adjusting for major depression at the time of evaluation and prescription of tranquillisers, ratings on two of the NES sub-scales (complex motor sequencing and 'other' signs) and on the Webster scale were significantly higher (more impaired) in patients compared with controls (P<0.05). With logistic regression, the NES was the main measure predictive of group outcome. There were no differences in scores of vascular risk or white matter but patients had patients had more atrophy.

CONCLUSIONS

The findings add to the evidence that late-life depression is associated with organic brain dysfunction, perhaps mediated by neurodegeneration or subtle vascular impairment. The use of the NES in subjects with depression should be replicated.

Amygdala and hippocampus volumes in pediatric major depression

BACKGROUND

The purpose of this study was to measure amygdala and hippocampus volumes in pediatric major depressive disorder (MDD) and to address the question of neuroanatomical continuity with adult-onset depression.

METHODS

We studied 20 children and adolescents with MDD (17 female subjects) and 24 healthy comparison subjects (16 female subjects) using 1.5 Tesla magnetic resonance imaging. Group differences in left and right amygdala and hippocampus volumes were examined using repeated measures analyses of covariance, adjusting for age, gender, and whole brain volume.

RESULTS

Depressed children had significant reductions of left and right amygdala volumes compared with healthy subjects. Hippocampus volumes did not differ between the groups. No significant correlations were found between amygdala volumes and depressive symptom severity, age at onset, or illness duration.

CONCLUSIONS

Smaller amygdalas are present early in the course of pediatric depression and may predispose to the development of this disorder or perhaps more generally of childhood mood disorders. Future research should examine the longitudinal course and functional correlates of amygdala volume abnormalities in childhood-onset depression, including their possible moderation by gender.

Hippocampal changes and white matter lesions in early-onset depression

BACKGROUND

Hippocampal volume reduction and increased prevalence of subcortical white matter lesions have been reported in late-life depression. We aimed to examine whether total number of subcortical white matter lesions were associated with reduced hippocampal volume in aged female subjects with early-onset depression (< 45 years) and healthy comparison subjects.

METHODS

The study included 28 middle-aged and elderly subjects with major depression and 41 age-matched control subjects. Hippocampal, parahippocampal gyrus, and orbitofrontal cortex volumes were determined using manual tracing methods. White matter lesions were rated from T2-weighted MRI scans using a semiquantitative classification scale.

RESULTS

After controlling for total brain volume and age, patients had reduced hippocampal volume due to right hippocampal volume decrease (2.84 mL vs. 3.12 mL, F = 16.6, p < .001). Parahippocampal and orbitofrontal volumes did not differ significantly between groups. Multiple linear regression analysis indicated that reduced hippocampal volume did not significantly correlate with total number of subcortical white matter lesions (t = .673, p = .518).

CONCLUSIONS

Right hippocampal volume was reduced in aged female early-onset subjects with depression. Total number of subcortical white matter lesions was not associated with the decrease in right hippocampal volume. Our data suggest hippocampal involvement, independent of subcortical white matter lesions, in the neuropathology of early-onset depression.