Prospective study of hippocampal volume and function in human subjects treated with corticosteroids

Neuroimaging and biomarker evidence of neurodegeneration in asthma

BACKGROUND

Epidemiologic studies have shown that Alzheimer's disease (AD) and related dementias (ADRD) are seen more frequently with asthma, especially with greater asthma severity or exacerbation frequency.

OBJECTIVE

To examine the changes in brain structure that may underlie this phenomenon, we examined diffusion-weighted magnetic resonance imaging (dMRI) and blood-based biomarkers of AD (phosphorylated tau 181, p-Tau181), neurodegeneration (neurofilament light chain, NfL), and glial activation (glial fibrillary acidic protein, GFAP).

METHODS

dMRI data were obtained in 111 individuals with asthma, ranging in disease severity from mild to severe, and 135 healthy controls. Regression analyses were used to test the relationships between asthma severity and neuroimaging measures, as well as AD pathology, neurodegeneration, and glial activation, indexed by plasma p-Tau181, NfL, and GFAP, respectively. Additional relationships were tested with cognitive function.

RESULTS

Asthma participants had widespread and large-magnitude differences in several dMRI metrics, which were indicative of neuroinflammation and neurodegeneration, and which were robustly associated with GFAP and, to a lesser extent, NfL. The AD biomarker p-Tau181 was only minimally associated with neuroimaging outcomes. Further, asthma severity was associated with deleterious changes in neuroimaging outcomes, which in turn were associated with slower processing speed, a test of cognitive performance.

CONCLUSIONS

Asthma, particularly when severe, is associated with characteristics of neuroinflammation and neurodegeneration, and may be a potential risk factor for neural injury and cognitive dysfunction. There is a need to determine how asthma may affect brain health and whether treatment directed toward characteristics of asthma associated with these risks can mitigate these effects.

Short-term mechanisms influencing volumetric brain dynamics

With the use of magnetic resonance imaging (MRI) and brain analysis tools, it has become possible to measure brain volume changes up to around 0.5%. Besides long-term brain changes caused by atrophy in aging or neurodegenerative disease, short-term mechanisms that influence brain volume may exist. When we focus on short-term changes of the brain, changes may be either physiological or pathological. As such determining the cause of volumetric dynamics of the brain is essential. Additionally for an accurate interpretation of longitudinal brain volume measures by means of neurodegeneration, knowledge about the short-term changes is needed. Therefore, in this review, we discuss the possible mechanisms influencing brain volumes on a short-term basis and set-out a framework of MRI techniques to be used for volumetric changes as well as the used analysis tools. 3D T₁-weighted images are the images of choice when it comes to MRI of brain volume. These images are excellent to determine brain volume and can be used together with an analysis tool to determine the degree of volume change. Mechanisms that decrease global brain volume are: fluid restriction, evening MRI measurements, corticosteroids, antipsychotics and short-term effects of pathological processes like Alzheimer's disease, hypertension and Diabetes mellitus type II. Mechanisms increasing the brain volume include fluid intake, morning MRI measurements, surgical revascularization and probably medications like anti-inflammatory drugs and anti-hypertensive medication. Exercise was found to have no effect on brain volume on a short-term basis, which may imply that dehydration caused by exercise differs from dehydration by fluid restriction. In the upcoming years, attention should be directed towards studies investigating physiological short-term changes within the light of long-term pathological changes. Ultimately this may lead to a better understanding of the physiological short-term effects of pathological processes and may aid in early detection of these diseases.

•

Fluid-restriction, evening MRI, corticosteroids, & antipsychotics decrease volume

•

Fluid-intake, morning MRI, surgical revascularization & medications increase volume

•

Short-term changes within the light of long-term pathological changes should be investigated

•

Short-term changes may introduce bias in longitudinal data

La escucha de música antes del TSST regula los niveles de cortisol en saliva independiente de la preferencia musical

El presente estudio evaluó si la escucha de música preferida por los participantes o la música relajante elegida por los investigadores previa al protocolo de estrés social modificado TSST (Trier Social Stress Test) afectaba el desempeño de las actividades realizadas durante el propio test, modulaba la respuesta de estrés que este induce, y en conjunto con el estresor, afectaba el desempeño en una tarea de atención en setenta y seis estudiantes universitarios asignados a uno de seis grupos: música relajante del investigador, música preferida por el participante y silencio, con o sin TSST. Los resultados mostraron que la escucha de ambos tipos de música provocó un incremento más lento en los niveles de cortisol en saliva luego del TSST, mientras que el aumento en la ansiedad estado evaluada con el IDARE (Inventario de Ansiedad Rasgo-Estado) fue semejante en todos los grupos. No se encontraron diferencias debidas a la música en el desempeño de las tareas evaluadas. Se discute sobre la modulación de la escucha de música en la respuesta fisiológica de estrés por la posible inducción de reacciones emocionales de manera independiente de la preferencia musical.

Organic changes in the central nervous system in children on chronic inhaled corticosteroid therapy

Treatment of asthma, the most common chronic respiratory disease in children, includes long-term inhaled corticosteroids (ICS). The purpose of this study was to analyze the impact of chronic inhaled steroids in children with asthma on changes in the central nervous system (CNS). Eleven children (8-17 years) on at least 4 years inhaled corticosteroid therapy were assessed with magnetic resonance imaging (MRI). All participants underwent a pediatric and neurological examination and spirometry. MRI data were obtained using a 1.5 T scanner with parallel imaging capability. Structural images consisted of axial T1, T2 using turbo spin echo, FLAIR and DWI sequences using typical parameters. Images were assessed in three planes (axial, coronal, and sagittal). Pediatric and neurological examination were normal in all children. In six, the MRI studies revealed small subcortical hyperintense foci. Three had more than five lesions, all of which were smaller than 3 mm. Features of mild supratentorial cortical atrophy were apparent in four. The cerebellum was unremarkable in all children imaged. In conclusion, patients receiving chronic inhaled corticosteroids had small subcortical hyperintense foci and features of mild supratentorial cortical atrophy. These findings suggest that ICS exposure may be associated with the development of organic changes in CNS. Further studies are needed to detail the extent of brain ICS-induced changes in children on chronic inhalative corticosteroid therapy as well as delayed impact of these changes on psychomotor functioning in adulthood.

Effect of early stress on hippocampal gray matter is influenced by a functional polymorphism in EAAT2 in bipolar disorder

Current views on the pathogenesis of psychiatric disorders focus on the interplay between genetic and environmental factors, with individual variation in vulnerability and resilience to hazards being part of the multifactorial development of illness. The aim of the study is to investigate the effect of glutamate transporter polymorphism SLC1A2-181A>C and exposure to Adverse Childhood Experiences (ACE) on hippocampal gray matter volume of patients with bipolar disorder (BD). Patients exposed to higher levels of ACE reported lower gray matter volume. The effect of SLC1A2-181A>C revealed itself only among patients exposed to lower levels of ACE, with T/T homozygotes showing the lowest, and G/G the highest, gray matter volume. The greatest difference between high and low exposures to ACE was observed in carriers of the G allele. Since the mutant G allele has been associated with a reduced transcriptional activity and expression of the transporter protein, we could hypothesize that after exposure to highest levels of ACE G/G homozygotes are more vulnerable to stress reporting the highest brain damage as a consequence of an excess of free glutamate.

Evaluation of spatial memory and locomotor activity during hypercortisolism induced by the administration of dexamethasone in adult male rats

In neurosurgery practice glucocorticoids are commonly used. Steroids may have central nervous system side effects affecting whole body, including steroid-induced mental agitation and psychosis. In experimental and clinical studies conducted by using dexamethasone (DEX), it has been reported that DEX adversely affects learning and memory skills. Unfortunately, there are yet no clinically accepted clinical approaches to prevent DEX-induced cognitive dysfunction. In this experimental study it was aimed to investigate the effect of chronic DEX administration on learning-memory and locomotor behaviors in adult male Sprague Dawley rats. In addition, it was also aimed to explore the potential favorable contribution of melatonin (MEL) and vitamin C (Vit C) having antioxidant and neuroprotective properties to the effects of DEX on learning-memory and locomotor behaviors. For this purpose, rats were injected 10mg/kg DEX intraperitoneally, both alone and in combination with MEL (40 mg/kg) and Vit C (100mg/kg), for 9 days, and the animals were tested using the radial arm maze and open field apparatus. The test results revealed that DEX caused a significant decrease in spatial memory and locomotor activities and MEL and Vit C failed to reverse losses in these activities. Furthermore, DEX led to a gradual weight loss that reached 30% of the initial weight at 9th day of the injection. DEX administration causes a generalized loss of behavioral activity of rats. Experimental studies devised to investigate effects of DEX should take into account this DEX-induced generalized behavioral loss when assessing the effects of DEX on learning and memory skills. This article is part of a Special Issue entitled SI: Brain and Memory.

Dexamethasone exposure and memory function in adult survivors of childhood acute lymphoblastic leukemia: A report from the SJLIFE cohort

BACKGROUND

Dexamethasone is used in acute lymphoblastic leukemia (ALL) treatment, though long-term impact on central nervous system (CNS) function is unclear. As glucocorticoids influence hippocampal function, we investigated memory networks in survivors of childhood ALL treated with dexamethasone or prednisone.

PROCEDURE

Neurocognitive assessment and functional magnetic resonance imaging (fMRI) were conducted in 38 adult survivors randomly recruited from cohorts treated on one of two standard treatment protocols, which differed primarily in the glucocorticoid administered during continuation therapy (dexamethasone [n = 18] vs. prednisone [n = 20]). Groups did not differ in age at diagnosis, age at evaluation, or cumulative intravenous or intrathecal methotrexate exposure.

RESULTS

Survivors treated with dexamethasone demonstrated lower performance on multiple memory-dependent measures, including story memory (P = 0.01) and word recognition (P = 0.04), compared to survivors treated with only prednisone. Dexamethasone treatment was associated with decreased fMRI activity in the left retrosplenial brain region (effect size = 1.3), though the small sample size limited statistical significance (P = 0.08). Story memory was associated with altered activation in left inferior frontal-temporal brain regions (P = 0.007).

CONCLUSIONS

Results from this pilot study suggest that adult survivors of ALL treated with dexamethasone are at increased risk for memory deficits and altered neural activity in specific brain regions and networks associated with memory function.

Exogenous glucocorticoids and adverse cerebral effects in children

Glucocorticoids are commonly used in treatment of paediatric diseases, but evidence of associated adverse cerebral effects is accumulating. The various pharmacokinetic profiles of the exogenous glucocorticoids and the changes in pharmacodynamics during childhood, result in different exposure of nervous tissue to exogenous glucocorticoids. Glucocorticoids activate two types of intracellular receptors, the mineralocorticoid receptor and the glucocorticoid receptor. The two receptors differ in cerebral distribution, affinity and effects. Exogenous glucocorticoids favor activation of the glucocorticoid receptor, which is associated with unfavorable cellular outcomes. Prenatal treatment with glucocorticoids can compromise brain growth and is associated with periventricular leukomalacia, attentions deficits and poorer cognitive performance. In the neonatal period exposure to glucocorticoids reduces neurogenesis and cerebral volume, impairs memory and increases the incidence of cerebral palsy. Cerebral effects of glucocorticoids in later childhood have been less thoroughly studied, but apparent brain atrophy, reduced size of limbic structures and neuropsychiatric symptoms have been reported. Glucocortioids affect several cellular structures and functions, which may explain the observed adverse effects. Glucocorticoids can impair neuronal glucose uptake, decrease excitability, cause atrophy of dendrites, compromise development of myelin-producing oligodendrocytes and disturb important cellular structures involved in axonal transport, long-term potentiation and neuronal plasticity. Significant maturation of the brain continues throughout childhood and we hypothesize that exposure to exogenous glucocorticoids during preschool and school age causes adverse cerebral effects. It is our opinion that studies of associations between exposure to glucocorticoids during childhood and impaired neurodevelopment are highly relevant.

Effects of glucocorticoids on mood, memory, and the hippocampus. Treatment and preventive therapy

Corticosteroids, such as prednisone and dexamethasone, are commonly prescribed medications that suppress the immune system and decrease inflammation. Common side effects of long-term treatment with corticosteroids include weight gain, osteoporosis, and diabetes mellitus. This paper reviews the literature on psychiatric and cognitive changes during corticosteroid therapy and potential treatment options. Hypomania and mania are the most common mood changes during acute corticosteroid therapy, although depression has also been reported. However, depression is reported to be more common than mania during long-term treatment with corticosteroids. A decline in declarative and working memory is also reported during corticosteroid therapy. Corticosteroids are associated with changes in the temporal lobe, detected by structural, functional, and spectroscopic imaging. The mood and cognitive symptoms are dose dependent and frequently occur during the first few weeks of therapy. Other risk factors are not well characterized. Controlled trials suggest that lithium and phenytoin can prevent mood symptoms associated with corticosteroids. Lamotrigine and memantine also have been shown to reverse, at least partially, the declarative memory effects of corticosteroids. Uncontrolled trials suggest that antipsychotics, anti-seizure medications, and perhaps some antidepressants can also be useful for normalizing mood changes associated with corticosteroids. Thus, both the symptoms and treatment response are similar to those of bipolar disorder. Moreover, corticosteroid-induced mood and cognitive alterations have been shown to be reversible with dose reduction or discontinuation of treatment.

The BDNF Val66Met polymorphism impacts parahippocampal and amygdala volume in healthy humans: incremental support for a genetic risk factor for depression

BACKGROUND

The role of the brain-derived neurotrophic factor (BDNF) in the pathogenesis of affective disorders such as depression has been controversial. Mounting evidence comes from structural imaging, that the functional BDNF Val66Met polymorphism influences the hippocampal volume with carriers of the 66Met allele (Val/Met and Met/Met group) having smaller hippocampi. Given that stress-induced atrophy of the hippocampus is associated with the pathogenesis of affective disorders, the functional BDNF Val66Met polymorphism could be an incremental risk factor.

METHOD

Eighty-seven healthy Caucasian participants underwent structural imaging and were genotyped for the BDNF Val66Met polymorphism. Data were analysed by means of voxel-based morphometry (VBM).

RESULTS

Region of interest (ROI) analyses revealed an association between the 66Met allele and smaller parahippocampal volumes and a smaller right amygdala. In addition, the whole-brain analysis showed that the thalamus, fusiformus gyrus and several parts of the frontal gyrus were smaller in 66Met allele carriers.

CONCLUSIONS

This study demonstrates that the impact of the BDNF Val66Met polymorphism is not confined to the hippocampus but also extends to the parahippocampal gyrus and the amygdala.

Attenuation of the effects of corticosteroids on declarative memory with lamotrigine

An extensive animal literature suggests that excessive corticosteroid exposure is associated with changes in memory and the hippocampus. Agents that decrease glutamate attenuate corticosteroid effects on the hippocampus. Minimal data are available on preventing or reversing corticosteroid effects on the human hippocampus. We previously reported that open-label lamotrigine was associated with significant improvement in declarative memory in corticosteroid-treated patients. We now examine the impact of 24 weeks of randomized, placebo-controlled lamotrigine therapy on declarative memory (primary aim) and hippocampal volume (secondary aim) in 28 patients (n=16 for lamotrigine, n=12 for placebo) taking prescription corticosteroids. All participants with data from at least one postbaseline assessment (n=9 for lamotrigine, n=11 for placebo) were included in the analysis. Declarative memory was assessed with the Rey Auditory Verbal Learning Test (RAVLT) at baseline and weeks 12 and 24. Hippocampal and total brain volumes were manually traced from MRI scans obtained at baseline and week 24. On the basis of an ANCOVA analysis, total words learned on the RAVLT at exit were significantly greater in the lamotrigine group (n=8, missing data or dropouts n=8) compared to the placebo group (n=11, dropout n=1). RAVLT scores in the lamotrigine group increased from mildly impaired to average range. Hippocampal volume changes were small in both lamotrigine (n=7) and placebo (n=7) groups during the 24-week assessment period and between-group differences were not significant. Results suggest that lamotrigine may improve declarative memory in patients taking prescription corticosteroids although differential dropout rate in the two groups is a concern.

Impact of levetiracetam on mood and cognition during prednisone therapy

PURPOSE

Corticosteroid excess is associated with impairment in declarative memory and hippocampal changes. In animals, phenytoin blocks the effects of stress on memory and hippocampal histology. Levetiracetam also shows neuroprotective properties in some animal models. This report examines whether levetiracetam prevents mood or cognitive changes secondary to prescription corticosteroids.

MATERIALS AND METHODS

Thirty outpatients given systemic corticosteroid therapy for asthma were randomized to either levetiracetam (1500 mg/day) or placebo given concurrently with the corticosteroids. Mood was assessed with the Hamilton rating scale for depression (HRSD), Young mania rating scale (YMRS) and activation (ACT) subscale of the internal state scale, declarative memory with the Rey auditory verbal learning test (RAVLT), and attention and executive functioning with the Stroop color and word test at baseline and after approximately 7 days of corticosteroid plus levetiracetam or placebo therapy.

RESULTS

Levetiracetam and placebo groups showed significant improvement from baseline to exit on RAVLT total words recalled with a non-significant change on other outcomes. No significant between-group differences were found. Initial prednisone dose showed a significant correlation with change in some cognitive domains.

CONCLUSIONS

Levetiracetam was well tolerated when combined with prednisone. Significant between-group differences in mood and cognition were not found.

The "steroid dementia syndrome": a possible model of human glucocorticoid neurotoxicity

Glucocorticoid medications cause neurotoxicity in animals under certain circumstances, but it is not known if this occurs in humans. We present the case of a 10-year-old boy with no prior psychiatric history and no prior exposure to glucocorticoid medication who received a single 5-week course of glucocorticoids for an acute asthma flare. Beginning during steroid treatment, and persisting for over 3 years after stopping treatment, he showed a significant decline from his pre-morbid academic performance and estimated IQ, verified by longitudinally administered testing and school records. Neuropsychological tests that are sensitive to glucocorticoid-induced cognitive impairments revealed global cognitive deficits consistent with primary hippocampal and prefrontal cortical dysfunction. The patient has a fraternal twin brother, who had previously achieved academic milestones in parallel with him; the patient began falling behind his twin in academic, developmental and social areas shortly after the steroid treatment. In the 3 years since stopping steroid medication, the patient has shown gradual but possibly incomplete resolution of his cognitive deficits. Quantitative brain magnetic resonance imaging (MRI), performed 38 months after steroid exposure revealed no gross abnormalities, but the patient's hippocampal volume was 19.5% smaller than that of his twin, despite the patient having a larger overall intracranial volume. Single photon emission computed tomography (SPECT) imaging, performed at the same time, suggested subtly decreased activity in the left posterior frontal and left parietal lobes. This case, along with others reported in the literature, suggests that certain individuals develop a "steroid dementia syndrome" after glucocorticoid treatment. Although this syndrome is uncommon, it is consistent with evolving theories of the neurotoxic or neuroendangering potential of glucocorticoids in some situations.

Effects of chronic prednisone therapy on mood and memory

BACKGROUND

In animals, stress and corticosteroids can be associated with both reversible and irreversible changes in the hippocampus. Changes in memory and hippocampal structure, perhaps in part due to cortisol elevations, are reported in some patients with mood disorders. Minimal data are available on the effects of long-term exposure to corticosteroids on the human hippocampus. We previously reported greater depressive symptom severity, poorer memory and smaller hippocampal volumes in patients with asthma or rheumatic diseases receiving long-term prednisone therapy than in controls.

METHODS

In this report, patients and controls were assessed a mean of 4 years after the first assessment to determine if depressive and manic symptoms and cognition remained stable, improved or worsened. Seven prednisone-treated patients and six controls were identified and agreed to reassessment with psychiatric symptom and neurocognitive measures. Follow-up MRIs for hippocampal volume analysis were available for two prednisone-treated participants.

RESULTS

With the exception of an increase in depressive symptoms in those receiving prednisone, participants and controls did not show significant change in mood or cognition from the initial assessment. One participant discontinued prednisone and showed improvement in psychiatric symptoms and cognition. Hippocampal volumes were available in two prednisone-treated participants and showed inconsistent findings.

LIMITATIONS

A limitation is the small sample size.

CONCLUSIONS

Our findings, although preliminary in nature, suggest that long-term prednisone therapy is associated with initial changes in mood, memory and hippocampal volume that appear to stabilize over time.