Memory processes in depressed geriatric patients with and without subcortical hyperintensities on MRI

Unilateral lower limb suspension: integrative physiological knowledge from the past 20 years (1991-2011)

In 1991, Hans Berg and colleagues published the first research investigation using unilateral lower limb suspension (ULLS) as a human model to study the influence of unloading on skeletal muscle. ULLS requires a participant to perform all activities with axillary crutches while wearing one thick-soled shoe. The elevated shoe eliminates ground contact with the adjacent foot, thereby unloading the lower limb. Today, ULLS is a well-known ground-based analog for microgravity. The present review will synthesize the physiological findings from investigations using ULLS to study the deleterious effects of unloading. Compromised human performance and the neuromuscular, musculoskeletal and circulatory mechanisms leading to altered function will be a major emphasis of the work. Results from prolonged bed rest will also be included in order for general comparisons to be made between analogs. Finally, the efficacy of exercise to mitigate the negative consequences of unloading is presented.

White matter hyperintensities, cortisol levels, brain atrophy and continuing cognitive deficits in late-life depression

BACKGROUND

Cerebrovascular changes and glucocorticoid mediated hippocampal atrophy are considered relevant for depression-related cognitive deficits, forming putative treatment targets.

AIMS

This study examined the relative contribution of cortisol levels, brain atrophy and white matter hyperintensities to the persistence of cognitive deficits in older adults with depression.

METHOD

Thirty-five people aged > or =60 years with DSM-IV major depression and twenty-nine healthy comparison controls underwent magnetic resonance imaging (MRI) and were followed up for 18 months. We analysed the relationship between baseline salivary cortisol levels, whole brain, frontal lobe and hippocampal volumes, severity of white matter hyperintensities and follow-up cognitive function in both groups by testing the interaction between the groups and these biological measures on tests of memory, executive functions and processing speed in linear regression models.

RESULTS

Group differences in memory and executive function follow-up scores were associated with ratings of white matter hyperintensities, especially of the deep white matter and periventricular regions. Compared with healthy controls, participants with depression scoring within the third tertile of white matter hyperintensities dropped two and three standard deviations in executive function and memory scores respectively. No biological measure related to group differences in processing speed, and there were no significant interactions between group and cortisol levels, or volumetric MRI measures.

CONCLUSIONS

White matter hyperintensities, rather than cortisol levels or brain atrophy, are associated with continuing cognitive impairments in older adults with depression. The findings suggest that cerebrovascular disease rather than glucocorticoid-mediated brain damage are responsible for the persistence of cognitive deficits associated with depression in older age.

Distinguishing between depression and dementia in older persons: neuropsychological and neuropathological correlates

Dementia and depression are frequently comorbid among older adult patients. Depression is related to cognitive decrement and can even represent the first signs of a neurodegenerative process. It can be difficult to distinguish depressed patients exhibiting the first signs of dementia from those whose cognition will improve with treatment. In this article, studies from the neuropsychological literature are reviewed that aid in accurate diagnosis and prognosis. Furthermore, the relationship between depression and dementia is explored by examining potential neurobiological mechanisms that may potentiate both syndromes in the context of the ongoing debate on depression as a prodrome and/or a risk factor for dementia. This article is concluded with suggestions for clinicians when deciding who to refer for neuropsychological assessment and with ideas for further research that might promote a better understanding of the complex association between depression and dementia during old age.

Subcortical hyperintensities impact cognitive function among a select subset of healthy elderly

Previous studies have examined the impact of subcortical hyperintensities (SH), a proxy measure of cerebrovascular disease, on the cognitive abilities of otherwise healthy older adults. However, there remains a limited understanding as to what extent this MRI marker of pathological processes explains the decline in specific cognitive functions that occur nearly ubiquitously with advanced age, especially in relation to other age-related imaging markers. In the present study we compared cognitive abilities between a sample of 53 older healthy adults (age range=50-79) and a sample of 53 younger adults (age range=21-40). As expected, the older group performed significantly worse on most cognitive measures compared to the younger group. Frontal volume and total grey matter volume were also significantly reduced among the older individuals compared to the younger individuals. SH volume was consistently associated with cognitive function in older adults, though, this relationship was evident only for a relatively small subset of older individuals with the most severe SH. These data suggest that the relationship between SH and cognition in the elderly is driven by a subset of individuals who may be in the earliest stages of vascular cognitive impairment. Further, the findings suggest that cognitive aging is largely determined by factors other than SH for most older adults.

Neuroimaging and cardiac correlates of cognitive function among patients with cardiac disease

In the present study, we examined the relationships between whole brain volume (WBV), subcortical hyperintensities (SH), indices of cardiac disease and cognitive function in nondemented cardiac patients with evidence of mild cerebrovascular disease. A total of 27 individuals with evidence of cardiac disease underwent neuropsychological examination, neuroimaging, and cardiac assessment. Cognition was assessed with the Dementia Rating Scale-2 (DRS). WBV and SH were quantified using a semi-automated thresholding program based on MRI. Correlational analyses revealed that WBV predicted performance on the overall DRS score, the attention subscale and the initiation/perseveration scale. SH were significantly associated with performance on the attention subscale, and the initiation/perseveration subscale. Regression analyses revealed that SH accounted for most of the variance in the initiation/perseveration scale, whereas WBV accounted for most of the variance in the attention scale. The only cardiac structural or functional variable related to the neurological indices was aortic diameter, which was strongly related to both neuroimaging variables, as well as performances on the DRS attention and initiation/perseveration subscales. Our results highlight the importance of overall brain parenchyma in determining cognitive status among patients at risk for cognitive decline and suggest that select indices of structural cardiac morphology may be related to the early phases of cerebrovascular disease and cognitive status.

Clinical correlates of cognitive decline in vascular dementia

OBJECTIVE

To determine whether demographic data, dementia severity, functional status, whole brain volume (WBV), or subcortical hyperintensity volume (SH) predict subsequent cognitive decline in vascular dementia (VaD).

BACKGROUND

The identification of variables that accurately predict progressive cognitive decline in dementia has important clinical implications.

METHODS

A cohort of 30 patients with VaD completed neurologic and neuropsychologic examinations and magnetic resonance imaging of the brain at baseline and again after 12 months. All participants met clinical and research criteria for VaD according to standard guidelines. Change scores were computed for measures of verbal fluency, verbal learning, and visual learning. Potential correlates of cognitive change included age, education, score on the Hachinski scale, WBV, SH, and functional ability.

RESULTS

As a group, lower WBV and lower Hachinski score correlated with decline in verbal fluency and visual learning, whereas lower Hachinski score correlated with decline in verbal learning. However, when subdivided by disease type, this pattern held only for individuals with evidence of a cortical stroke at baseline. No clinical variables correlated with cognitive decline among individuals without a cortical infarction.

CONCLUSIONS

Assessment of cognitive decline in VaD should be guided by dementia subtype, with particular attention directed at severity of cerebral atrophy rather than classic symptoms of infarction.

Neurocognitive profiles in elderly patients with frontotemporal degeneration or major depressive disorder

Major depressive disorder (MDD) and frontotemporal dementia (FTD) are both disorders in elderly populations that involve the prefrontal cortex and appear to have similar neurocognitive deficits. This review examined whether there are testable deficits in cognition that are consistent across individuals within the same neuropathological condition that could be used to facilitate early diagnoses. Medline and PsychInfo databases were searched for cognitive studies of depressed and FTD patients that used a matched control group and reported findings with means and standard deviations (N = 312). Effect sizes for FTD patients with mild and moderately advanced disease were compared to effect sizes within subgroups of depressed patients, such as inpatients, outpatients and community volunteers. Moderately advanced FTD patients were more impaired than depressed patients over all domains, particularly in language ability, although depressed inpatients appeared similar to FTD patients in some domains. Effect sizes for FTD patients who were in the mild, or early, stage of the disease (MMSE = 28) were similar to those of depressed outpatients but slightly worse than those of community volunteers in all domains except semantic memory and executive ability. In the latter two domains, even mild FTD patients had notably large deficits. All FTD patients showed more severe deficits in some domains relative to other domains. In contrast, depressed patients tended to vary by clinical presentation or disease severity, but the magnitude of impairment for each subgroup remained relatively consistent across domains and they did not have the severe focal deficits in one or two domains demonstrated by FTD patients.

Depression in the elderly: new concepts and therapeutic approaches

Depression is one of the leading causes of suffering in the elderly, but it is often under-diagnosed and under-treated, partly due to the false belief that depression is a common aspect of aging. Depression in the elderly is frequently comorbid with medical illnesses, may often be expressed by somatic complaints, and may be a risk factor for other diseases such as dementia and coronary artery disease. Depression decreases the quality of life and increases disability and the risk of mortality, also due to suicide. Although several effective antidepressant drugs are available, with a favorable therapeutic index, non-pharmacological treatments, such as psychotherapy and exercise, should receive greater attention, since combination therapy is probably more effective.

Neuroimaging correlates of dementia rating scale performance at baseline and 12-month follow-up among patients with vascular dementia

The authors previously reported that subcortical hyperintensity (SH) and whole-brain volume (WBV) each covary with different subscale scores of the Mattis Dementia Rating Scale (MDRS) among vascular dementia (VaD) patients. The present longitudinal analysis examined these relationships for change. The authors found that SH volume increased and WBV decreased significantly over 12 months. At baseline, SH volume accounted for significant variance in MDRS total score and every subscale score, except Memory. WBV was unrelated to any MDRS measure. After 12 months, SH volume was related only to the Construction subscale score, whereas WBV accounted for the majority of variance in Attention and Memory subscale performance. These findings indicate that although SH volume increases with disease progression, the relative impact of SH volume on cognitive status decreases among patients with advanced VaD.

MRI subcortical hyperintensities in old and very old depressed outpatients: the important role of age in late-life depression

OBJECTIVE

There is increasing evidence that cerebrovascular factors play a key role in the etiology of late-life depression. This study examined the severity of subcortical hyperintensities (SH) and the relationship between SH and depression characteristics in two samples of elderly depressed outpatients differing in age.

METHODS

The samples consisted of 59 subjects age 60 and over, (69+/-5.6 years), who participated in a trial of sertraline, and 111 subjects age 75 and over, (79+/-4.1 years), who participated in a trial of citalopram.

RESULTS

The citalopram group was significantly older than the sertraline group and had more severe SH (72% vs. 42% high ratings). The High SH group was significantly older than the Low SH group in the sertraline study but there was no difference in age in the SH groups in the citalopram sample. There was no relationship between SH severity and baseline depression or age of onset. However, age strongly correlated with later age of onset. There was no relationship between SH severity and cardiovascular risk factors or treatment response in the sertraline sample.

CONCLUSION

Age is a major factor for the development of SH and late-life depression. There may not be an association between SH and depression severity, cardiovascular risk factors, or treatment response in geriatric depressed outpatients. The etiologic factors and clinical course of late-life depression requires further study.

Executive dysfunction in subcortical ischaemic vascular disease

BACKGROUND

Executive dysfunction has been reported in patients with subcortical-frontal pathology, even in the absence of dementia.

OBJECTIVE

This study was undertaken to determine if impairments in executive functioning could be found in non-demented patients with subcortical lacunes.

METHODS

Cross sectional comparison between older control subjects (n=27) and non-demented patients with one or more subcortical lacunes (n=12). All participants were administered a neuropsychological test battery incorporating three measures of executive functioning, the Stroop interference test, California card sorting test, and the initiation-perseveration subtest of the Mattis dementia rating scale.

RESULTS

No group differences were found on measures of recent verbal memory, language, or spatial ability. Normal controls performed better than patients with lacunes in visual memory. On the Stroop interference test, patients with lacunes performed as well as controls on the colour naming condition but slower on the interference condition. Patients with lacunes also generated fewer correct sorts on the California card sort test and achieved lower scores on the initiation-perseveration subtest. Executive measures were correlated with extent of white matter signal hyperintensity but not number of lacunes.

CONCLUSION

Subcortical ischaemic vascular disease is associated with subtle declines in executive functioning and visual memory, even in non-demented patients. The pattern of cognitive impairment after subcortical lacunes is consistent with models of subcortical-frontal circuits.

Performance on the Mattis Dementia Rating Scale in patients with vascular dementia: relationships to neuroimaging findings

Impairment on screening measures such as the Mattis Dementia Rating Scale (MDRS) provides evidence of dementia in patients with cerebrovascular disease. However, the relationships between neuroimaging findings and performance on the MDRS in vascular dementia (VD) have not been determined. In the present study, we examined the relationships between subcortical hyperintensity (SH) volume and whole brain volume (WBV) on the subscales and total score of the MDRS. Results revealed that SH accounted for a significant amount of variance on the Initiation/Perseveration and Construction subscales, whereas WBV accounted for a significant amount of variance on the Memory subscale. The total score on the MDRS was found to be significantly related to WBV but not SH. These results suggest that subcortical damage and brain volume account for different aspects of cognitive decline in VD and that overall cognitive impairment may reflect cortical and subcortical involvement.

Depression in late life, cognitive decline and white matter pathology in two clinico-pathologically investigated cases

CASE REPORTS

We report two cases of late life depression who became progressively more resistant to treatment, developed cognitive impairment, and began to exhibit neurological abnormalities and evidence of vascular disease. A discussion of the clinical features of the cases is accompanied by reports of neuropathology and neuroimaging findings. Extensive white matter lesions were present on computed tomography in both patients, and basal ganglia infarcts were seen in one. Neuropathology revealed evidence of cerebral atrophy, demyelination and white matter lesions in addition to cerebrovascular and generalised vascular disease. Neither patient exhibited Alzheimer pathology outwith the norm for their age. We believe this to be the first report of neuropathological findings in depression with white matter changes.

LITERATURE REVIEW

The pathological basis of white matter lesions and their relationship to depression, its age of onset and clinical features is addressed in relation to the cases described. Pathological investigation of white matter lesions has not previously been carried out in depression and hypotheses regarding their nature in this illness are based on extrapolation from research in a variety of other disorders. The association of depression with vascular risk factors is considered, as is the relationship between depression and cognitive deficits. There is a need for further investigation in this area.