Reduced prefrontal N-acetylaspartate in stroke patients with apathy

The neurobiology of wellness: 1H-MRS correlates of agency, flexibility and neuroaffective reserves in healthy young adults

Proton magnetic resonance spectroscopy (¹H-MRS) is a noninvasive imaging technique that measures the concentration of metabolites in defined areas of the human brain in vivo. The underlying structure of natural metabolism-emotion relationships is unknown. Further, there is a wide range of between-person differences in metabolite concentration in healthy individuals, but the significance of this variation for understanding emotion in healthy humans is unclear. Here we investigated the relationship of two emotional constructs, agency and flexibility, with the metabolites glutamate and glutamine (Glx), N-acetylaspartate (tNAA), choline (Cho), creatine (tCr), and myo-inositol (Ins) in the right dorsal anterior cingulate cortex (dACC) in medically and psychiatrically healthy volunteers (N = 20, 9 female; mean age = 22.8 years, SD = 3.40). The dACC was selected because this region is an integrative hub involved in multiple brain networks of emotion, cognition and behavior. Emotional traits were assessed using the Multidimensional Personality Questionnaire Brief Form (MPQ-BF), an empirically derived self-report instrument with an orthogonal factor structure. Phenotypes evaluated were positive and negative agency (MPQ-BF Social Potency, Aggression), emotional and behavioral flexibility (MPQ-BF Absorption, Control-reversed), and positive and negative affect (MPQ-BF Social Closeness; Stress Reaction, Alienation). The resting concentration of tNAA in the dACC was robustly positively correlated with Absorption (r = +0.56, unadjusted p = .005), moderately positively correlated with Social Potency (r = +0.42, unadjusted p = .03), and robustly negatively correlated with Aggression (r = −0.59, unadjusted p = .003). Absorption and Aggression accounted for substantial variance in tNAA (R² = 0.31, 0.35; combined R² = 0.50), and survived correction for multiple comparisons (Holm-Bonferroni adjusted p = .032, 0.021, respectively). dACC Glx and Cho had modest relationships with behavioral flexibility and social affiliation that did not survive this multiple correction, providing effect sizes for future work. Principal Component Analysis (PCA) revealed a three-factor orthogonal solution indicating specific relationships between: 1) Glx and behavioral engagement; 2) Cho and affiliative bonding; and 3) tNAA and a novel dimension that we term neuroaffective reserves. Our results inform the neurobiology of agency and flexibility and lay the groundwork for understanding mechanisms of natural emotion using ¹H-MRS.

Network neuroscience of apathy in cerebrovascular disease

Apathy is a reduction in motivated goal-directed behavior (GDB) that is prevalent in cerebrovascular disease, providing an important opportunity to study the mechanistic underpinnings of motivation in humans. Focal lesions, such as those seen in stroke, have been crucial in developing models of brain regions underlying motivated behavior, while studies of cerebral small vessel disease (SVD) have helped define the connections between brain regions supporting such behavior. However, current lesion-based models cannot fully explain the neurobiology of apathy in stroke and SVD. To address this, we propose a network-based model which conceptualizes apathy as the result of damage to GDB-related networks. A review of the current evidence suggests that cerebrovascular disease-related pathology can lead to network changes outside of initially damaged territories, which may propagate to regions that share structural or functional connections. The presentation and longitudinal trajectory of apathy in stroke and SVD may be the result of these network changes. Distinct subnetworks might support cognitive components of GDB, the disruption of which results in specific symptoms of apathy. This network-based model of apathy may open new approaches for investigating its underlying neurobiology, and presents novel opportunities for its diagnosis and treatment.

Serial Cerebral Metabolic Changes in Patients With Ischemic Stroke Treated With Autologous Bone Marrow Derived Mononuclear Cells

Purpose: Cell-based therapy offers new opportunities for the development of novel treatments to promote tissue repair, functional restoration, and cerebral metabolic balance. N-acetylasperate (NAA), Choline (Cho), and Creatine (Cr) are three major metabolites seen on proton magnetic resonance spectroscopy (MRS) that play a vital role in balancing the biochemical processes and are suggested as markers of recovery. In this preliminary study, we serially monitored changes in these metabolites in ischemic stroke patients who were treated with autologous bone marrow-derived mononuclear cells (MNCs) using non-invasive MRS.

Materials and Methods: A sub-group of nine patients (3 male, 6 female) participated in a serial MRS study, as part of a clinical trial on autologous bone marrow cell therapy in acute ischemic stroke. Seven to ten million mononuclear cells were isolated from the patient's bone marrow and administered intravenously within 72 h of onset of injury. MRS data were obtained at 1, 3, and 6 months using a whole-body 3.0T MRI. Single voxel point-resolved spectroscopy (PRESS) was obtained within the lesion and contralesional gray matter. Spectral analysis was done using TARQUIN software and absolute concentration of NAA, Cho, and Cr was determined. National Institute of Health Stroke Scale (NIHSS) was serially recoreded. Two-way analysis of variance was performed and p < 0.05 considered statistically significant.

Results: All metabolites showed statistically significant or clear trends toward lower ipsilesional concentrations compared to the contralesional side at all time points. Statistically significant reductions were found in ipsilesional NAA at 1M and 3M, Cho at 6M, and Cr at 1M and 6M (p < 0.03), compared to the contralesional side. Temporally, ipsilesional NAA increased between 3M and 6M (p < 0.01). On the other hand, ipsilesional Cho showed continued decline till 6M (p < 0.01). Ipsilesional Cr was stable over time. Contralesional metabolites were relatively stable over time, with only Cr showing a reduction 3M (p < 0.02). There was a significant (p < 0.03) correlation between ipsilesional NAA and NIHSS at 3M follow-up.

Conclusion: Serial changes in metabolites suggest that MRS can be applied to monitor therapeutic changes. Post-treatment increasing trends of NAA concentration and significant correlation with NIHSS support a potential therapeutic effect.

The anatomy of apathy: A neurocognitive framework for amotivated behaviour

Apathy is a debilitating syndrome associated with many neurological disorders, including several common neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease, and focal lesion syndromes such as stroke. Here, we review neuroimaging studies to identify anatomical correlates of apathy, across brain disorders. Our analysis reveals that apathy is strongly associated with disruption particularly of dorsal anterior cingulate cortex (dACC), ventral striatum (VS) and connected brain regions. Remarkably, these changes are consistent across clinical disorders and imaging modalities. Review of the neuroimaging findings allows us to develop a neurocognitive framework to consider potential mechanisms underlying apathy. According to this perspective, an interconnected group of brain regions - with dACC and VS at its core - plays a crucial role in normal motivated behaviour. Specifically we argue that motivated behaviour requires a willingness to work, to keep working, and to learn what is worth working for. We propose that deficits in any one or more of these processes can lead to the clinical syndrome of apathy, and outline specific approaches to test this hypothesis. A richer neurobiological understanding of the mechanisms underlying apathy should ultimately facilitate development of effective therapies for this disabling condition.

Imaging Markers of Post-Stroke Depression and Apathy: a Systematic Review and Meta-Analysis

Several brain imaging markers have been studied in the development of post-stroke depression (PSD) and post-stroke apathy (PSA), but inconsistent associations have been reported. This systematic review and meta-analysis aims to provide a comprehensive and up-to-date evaluation of imaging markers associated with PSD and PSA. Databases (Medline, Embase, PsycINFO, CINAHL, and Cochrane Database of Systematic Reviews) were searched from inception to July 21, 2016. Observational studies describing imaging markers of PSD and PSA were included. Pooled odds ratios (OR) and 95% confidence intervals (CI) were calculated to examine the association between PSD or PSA and stroke lesion laterality, type, and location, also stratified by study phase (acute, post-acute, chronic). Other imaging markers were reviewed qualitatively. The search retrieved 4502 studies, of which 149 studies were included in the review and 86 studies in the meta-analyses. PSD in the post-acute stroke phase was significantly associated with frontal (OR 1.72, 95% CI 1.34–2.19) and basal ganglia lesions (OR 2.25, 95% CI 1.33–3.84). Hemorrhagic stroke related to higher odds for PSA in the acute phase (OR 2.58, 95% CI 1.18–5.65), whereas ischemic stroke related to higher odds for PSA in the post-acute phase (OR 0.20, 95% CI 0.06–0.69). Frequency of PSD and PSA is modestly associated with stroke type and location and is dependent on stroke phase. These findings have to be taken into consideration for stroke rehabilitation programs, as this could prevent stroke patients from developing PSD and PSA, resulting in better clinical outcome.

Molecular Neuroimaging in Posttraumatic Stress Disorder

Over the past decade, an increasing number of neuroimaging studies have provided insight into the neurobiological mechanisms of posttraumatic stress disorder (PSTD). In particular, molecular neuroimaging techniques have been employed in examining metabolic and neurochemical processes in PTSD. This article reviews molecular neuroimaging studies in PTSD and focuses on findings using three imaging modalities including positron emission tomography (PET), single photon emission computed tomography (SPECT), and magnetic resonance spectroscopy (MRS). Although there were some inconsistences in the findings, patients with PTSD showed altered cerebral metabolism and perfusion, receptor bindings, and metabolite profiles in the limbic regions, medial prefrontal cortex, and temporal cortex. Studies that have investigated brain correlates of treatment response are also reviewed. Lastly, the limitations of the molecular neuroimaging studies and potential future research directions are discussed.

Neuropathological sequelae of Human Immunodeficiency Virus and apathy: A review of neuropsychological and neuroimaging studies

Apathy remains a common neuropsychiatric disturbance in the Human Immunodeficiency Virus (HIV-1) despite advances in anti-retroviral treatment (ART). The goal of the current review is to recapitulate findings relating apathy to the deleterious biobehavioral effects of HIV-1 in the post-ART era. Available literatures demonstrate that the emergence of apathy with other neurocognitive and neuropsychiatric symptoms may be attributed to neurotoxic effects of viral proliferation, e.g., aggregative effect of Tat and gp120 on apoptosis, transport and other enzymatic reactions amongst dopaminergic neurons and neuroglia. An assortment of neuroimaging modalities converge on the severity of apathy symptoms associated with the propensity of the virus to replicate within frontal-striatal brain circuits that facilitate emotional processing. Burgeoning research into functional brain connectivity also supports the effects of microvascular and neuro-inflammatory injury linked to aging with HIV-1 on the presentation of neuropsychiatric symptoms. Summarizing these findings, we review domains of HIV-associated neurocognitive and neuropsychiatric impairment linked to apathy in HIV. Taken together, these lines of research suggest that loss of affective, cognitive and behavioral inertia is commensurate with the neuropathology of HIV-1.

Ankle brachial pressure index as a marker of apathy in a community-dwelling population

BACKGROUND

Apathy is defined as a lack of interest or emotion. Several studies have shown the relationship between apathy and atherosclerotic change in poststroke patients. Although apathy is confused with depression, it might be a specific neuropsychiatric syndrome separate from depression.

OBJECTIVE

To clarify the relationship between atherosclerotic change and apathy in a community-dwelling population, which does not include the psychologic factors associated with stroke events.

METHODS

The ankle brachial pressure index (ABI) was measured using a volume-plethymographic apparatus in 860 volunteers (315 males and 545 females) who participated in the Iwaki Health Promotion Project 2008. Starkstein's apathy score and the Center for Epidemiologic Studies Depression Scale (CES-D) were used to assess the psychologic status. The association between the ABI and apathy was assessed by a multiple linear regression analysis.

RESULTS

Gender and low-density lipoprotein (LDL)-cholesterol were independently and significantly associated with the CES-D score. We did not find any association between CES-D score and the ABI. In addition, the extent of education and the ABI were independently and significantly associated with the apathy scale (AS).

CONCLUSION

In a community-dwelling population, a lower ABI score was an independent risk factor for a higher AS score, but not for a higher CES-D score. Apathy and depression may have different etiologies in vascular factors.

Are the available apathy measures reliable and valid? A review of the psychometric evidence

OBJECTIVE

Apathy is highly prevalent among neuropsychiatric populations and is associated with greater morbidity and worse functional outcomes. Despite this, it remains understudied and poorly understood, primarily due to lack of consensus definition and clear diagnostic criteria for apathy. Without a gold standard for defining and measuring apathy, the availability of empirically sound measures is imperative. This paper provides a psychometric review of the most commonly used apathy measures and provides recommendations for use and further research.

METHODS

Pertinent literature databases were searched to identify all available assessment tools for apathy in adults aged 18 and older. Evidence of the reliability and validity of the scales were examined. Alternate variations of scales (e.g., non-English versions) were also evaluated if the validating articles were written in English.

RESULTS

Fifteen apathy scales or subscales were examined. The most psychometrically robust measures for assessing apathy across any disease population appear to be the Apathy Evaluation Scale and the apathy subscale of the Neuropsychiatric Inventory based on the criteria set in this review. For assessment in specific populations, the Dementia Apathy Interview and Rating for patients with Alzheimer's dementia, the Positive and Negative Symptom Scale for schizophrenia populations, and the Frontal System Behavior Scale for patients with frontotemporal deficits are reliable and valid measures.

CONCLUSION

Clinicians and researchers have numerous apathy scales for use in broad and disease-specific neuropsychiatric populations. Our understanding of apathy would be advanced by research that helps build a consensus as to the definition and diagnosis of apathy and further refine the psychometric properties of all apathy assessment tools.

Apathy following stroke

OBJECTIVE

We will review the available evidence on the frequency, clinical correlates, mechanism, and treatment of apathy following stroke.

METHODS

We have explored relevant databases (that is, PubMed, MEDLINE, and PsycINFO) using the following key words and their combinations: apathy, motivation, abulia, stroke, cerebrovascular disease, basal ganglia, prefrontal cortex, anterior cerebral infarction, and thalamus.

RESULTS

The frequency of apathy following stroke has been consistently estimated between 20% and 25%. It appears to be associated with the presence of cognitive impairment, a chronic course characterized by progressive functional decline, and with disruption of neural networks connecting the anterior cingulate gyrus, the dorsomedial frontal cortex, and the frontal pole with the ventral aspects of the caudate nucleus, the anterior and ventral globus pallidus, and the dorsomedian and intralaminar thalamic nuclei. Published treatment studies have been mostly limited to anecdotal case reports, generally using dopamine agonists or stimulant medications. Cholinesterase inhibitors and nefiracetam may significantly reduce apathetic symptoms. However, their efficacy was examined in relatively small clinical trials that require replication.

CONCLUSION

Apathy is a frequent neuropsychiatric complication of stroke that, although often associated with depression and cognitive impairment, may occur independently of both. Its presence has been consistently associated with greater functional decline. However, there is no conclusive evidence about which is the best treatment for this condition.

A longitudinal view of apathy and its impact after stroke

BACKGROUND AND PURPOSE

Stroke survivors are often described as apathetic. Because apathy may be a barrier to participation in promising therapies, more needs to be learned about apathy symptoms after stroke. The specific objective was to estimate the extent to which apathy changes with time over the first year after stroke and the impact of apathy on recovery.

METHODS

The Apathy Assessed cohort was formed from stroke survivors participating in a longitudinal study of health-related quality of life after stroke. A family caregiver completed an apathy questionnaire by telephone at 1, 3, 6, and 12 months after stroke (n=408). Group-based trajectory modeling and ordinal regression were used to identify distinctive groups of individuals with similar trajectories of apathy over the first year after stroke and predictors of apathy trajectory.

RESULTS

Both 3- and 5-group trajectory models fit the data. We used the 5-group model because of the potential to further explore the apathy construct. The largest group (50%) had low apathy and 33% had minor apathy that remained stable throughout the first year after stroke. A small proportion (3%) of the study sample had high apathy that remained high. Two other groups of almost equal size (7%) showed worsening and improving apathy. Poor cognitive status, low functional status, and high comorbidity predicted higher apathy. High apathy had a significant negative effect on physical function, participation, health perception, and physical health over the first 12 months after stroke.

CONCLUSION

Some degree of apathy was prevalent and persistent after stroke and was predicted by older age, poor cognitive status, and low functional status after stroke. Even a minor level of apathy had an important and statistically significant impact on stroke outcomes.

The use of proton magnetic resonance spectroscopy in PTSD research--meta-analyses of findings and methodological review

Different neuroimaging techniques provided evidence for structural and functional brain alterations in posttraumatic stress disorder (PTSD). Due to technical improvements, especially concerning localization techniques and more reliable analysis methods, one technique, proton magnetic resonance spectroscopy ((1)H-MRS), has increasingly become of interest because it allows further insight into metabolic mechanisms that may contribute to these alterations. The aim of this article is, therefore, to review recent studies utilizing (1)H-MRS of the hippocampus and other brain structures in PTSD. Using meta-analytic methods, we attempted to answer the question if PTSD, as compared to different types of control samples, is accompanied by altered neurometabolite ratios and concentrations in the tissue of different brain regions. A second intent was to review methodological aspects to advise on a minimal standard for reliable results with respect to the application of (1)H-MRS in PTSD. Finally, we discussed the implications of the findings with respect to current PTSD models and future research.

Apathy and the processing of novelty in schizophrenia

Apathy is a common negative symptom in schizophrenia that has been associated with poor medication compliance and treatment outcome. Recent studies in neurological patients have observed an association between apathy and reduced attention to novel stimuli. We evaluated whether patients with schizophrenia demonstrate a similar relationship. Participants included 20 patients with schizophrenia and 20 healthy comparison subjects matched for age, sex, handedness, and parental education. A self-paced visual novelty task was presented which assessed the duration that participants looked at frequent standard stimuli, infrequent target stimuli, and novel stimuli. Attention to novelty was defined as the duration of viewing novel relative to standard stimuli. Apathy was assessed with the Marin Apathy Evaluation Scale. Results revealed significantly greater self- and informant-reported apathy, slower reaction time to target stimuli, and longer viewing times to the stimuli, but not reduced attention to the novel stimuli, in the patient group. Although greater self-report of apathy was associated with longer viewing times for all stimuli in the patient group, this was accounted for by depressed mood. The present findings indicate that schizophrenia is associated with slowed information processing, but do not support the hypothesis that apathy in schizophrenia is associated with abnormal processing of novelty.

Depression or apathy and functional recovery after stroke

OBJECTIVES

While depression and apathy are common after stroke, past studies have done little to examine the influence of these two symptoms on functional outcome respectively. This study was designed to examine the effect of depression or apathy on functional recovery after stroke in 237 Japanese stroke patients.

METHODS

We assessed the psychological status using self-rating scales [the Zung Self-Rating Depression Scale (SDS) for depression and the Apathy Scale (AS) for apathy] and an observer-rating scale [the Neuropsychiatric Inventory (NPI)]. We assessed physical disability using the Functional Independence Measurement (FIM). Post-hoc test and multiple regression analysis were used to determine the independent effects of post-stroke depression and apathy on functional outcome.

RESULTS

Depression was observed in 75 (31.6%) using SDS and 88 (40.2%) using NPI, and apathy in 95 (40.1%) using AS and 42 (19.2%) using NPI, respectively. Post-hoc test and multiple regression analysis indicated that the cognitive variable (Mini-Mental State Examination: MMSE score) and AS score, but not SDS score, correlated negatively with improvement in FIM.

CONCLUSIONS

Apathy might be more frequently associated with functional abilities and likely interact with the recovery process as compared with depression after stroke.