Network neuroscience of apathy in cerebrovascular disease

The relationship between rehabilitation motivation and upper limb motor function in stroke patients

Objective

Insufficient motivation among post-stroke survivors may be an important factor affecting their motor function recovery. This study seeks to investigate the relationship between motivation and functional recovery in stroke patients undergoing rehabilitation training.

Materials and methods

103 stroke patients with upper limb impairments were studied during their hospital stays. Assessments were done before and after rehabilitation training to measure motivation, emotional state, motor function, and independence in daily activities. Data analysis was conducted to examine the distribution of these factors among the participants. Pearson and Spearman correlation analyses were used to study the relationships between motivation, emotional state, and motor function. Patients were divided into high and low motivation groups based on the Rehabilitation Motivation Scale (RMS), and chi-square and rank-sum tests were used to compare functional differences before and after treatment among patients with varying levels of motivation.

Results

66 participants were found to have low motivation in the initial assessment of the RMS (64.08%). Consistency in motivation levels was observed among patients with high motivation (r = 0.648, P<0.001). Apathy was identified as the main factor affecting motivation in patients with low motivation (p = 0.027), while depression and anxiety were not significantly correlated. Motivation was strongly linked to improvements in upper limb motor function, daily living activities, and self-exercise duration (p < 0.001) for stroke patients undergoing rehabilitation. Post-training, there was a notable increase in motivation, motor function, and independence in daily activities (p < 0.001). Increased rehabilitation motivation was linked to better upper limb motor function and daily independence in patients, particularly those with low motivation. This correlation was significant for both the FMA-UE and FIM scores.

Discussion

Old patients with poor upper limb motor function often have low motivation, which hinders their recovery. Using strategies to boost motivation in stroke patients with impaired upper limb function could greatly improve their rehabilitation and motor skills. It is crucial to prioritize these intervention strategies.

Conclusion

Enhancing rehabilitation motivation in stroke patients with low motivation and upper limb motor impairments can foster the restoration of their functional capabilities.

Apathy After Stroke: Incidence, Symptom Trajectory, and Impact on Quality of Life and Disability

BACKGROUND AND OBJECTIVES

Apathy is one of the most common symptoms following stroke and is often associated with worse functional outcome and poor quality of life (QoL). The trajectory of apathy symptoms has been previously described, and different trajectories have been identified. We determined group and individual changes in apathy symptomatology from the acute phase until 1 year after stroke. We also examined the association of apathy and depression with disability and QoL 1 year after stroke.

METHODS

We measured apathy in a cohort of ischemic stroke survivors at 4 time points from 0 to 12 months after stroke. The Apathy Evaluation Scale (AES) and Dimensional Apathy Scale (DAS) were administered at each time point. Where possible we obtained apathy measured from carers. Depression was assessed with the Geriatric Depression Scale (GDS). Disability and QoL were assessed with the modified Rankin Scale (mRS) and 36-Item Short Form Survey (SF-36). We examined the cross-sectional and individual trajectory of apathy symptoms in each dimension and looked at associations of apathy and depression soon after stroke with mRS and SF-36 at 1 year.

RESULTS

Of 200 participants enrolled, 165 completed apathy measures at 12 months. Patient-rated apathy scores increased in both tests at the group level (AES: χ2(3) = 9.86, p = 0.019; DAS: χ2(3) = 8.49, p = 0.037) and individual level (AES: β = 0.13, p = 0.002; DAS β = 0.13, p = 0.005; DAS: executive β = 0.08, p < 0.001). By contrast, carer-rated apathy did not significantly increase (AES: χ2(3) = 0.75, p = 0.862; DAS: χ2(3) = 2.45, p = 0.484). Apathy scores were associated with worse mRS and SF-36, although most associations were no longer significant when controlling for depression. GDS was associated with worse mRS and SF-36 after controlling for covariates and apathy (mRS: β = 0.08, p = 0.006; SF-36 Mental Component Summary: β = -1.53, p < 0.001; SF-36 Physical Component Summary: β = -0.57, p = 0.016).

DISCUSSION

Self-reported apathy progressively increases after stroke, especially in the executive dimension. Apathy is associated with worse QoL and greater disability, although some of these associations might be mediated by depression.

Post-Stroke Neuropsychiatric Complications: Types, Pathogenesis, and Therapeutic Intervention

Almost all stroke survivors suffer physical disabilities and neuropsychiatric disturbances, which can be briefly divided into post-stroke neurological diseases and post-stroke psychiatric disorders. The former type mainly includes post-stroke pain, post-stroke epilepsy, and post-stroke dementia while the latter one includes post-stroke depression, post-stroke anxiety, post-stroke apathy and post-stroke fatigue. Multiple risk factors are related to these post-stroke neuropsychiatric complications, such as age, gender, lifestyle, stroke type, medication, lesion location, and comorbidities. Recent studies have revealed several critical mechanisms underlying these complications, namely inflammatory response, dysregulation of the hypothalamic pituitary adrenal axis, cholinergic dysfunction, reduced level of 5-hydroxytryptamine, glutamate-mediated excitotoxicity and mitochondrial dysfunction. Moreover, clinical efforts have successfully given birth to many practical pharmaceutic strategies, such as anti-inflammatory medications, acetylcholinesterase inhibitors, and selective serotonin reuptake inhibitors, as well as diverse rehabilitative modalities to help patients physically and mentally. However, the efficacy of these interventions is still under debate. Further investigations into these post-stroke neuropsychiatric complications, from both basic and clinical perspectives, are urgent for the development of effective treatment strategies.

Reward network dysfunction is associated with cognitive impairment after stroke

Stroke survivors not only suffer from severe motor, speech and neurocognitive deficits, but in many cases also from a "lack of pleasure" and a reduced motivational level. Especially apathy and anhedonic symptoms can be linked to a dysfunction of the reward system. Rewards are considered as important co-factor for learning, so the question arises as to why and how this affects the rehabilitation of stroke patients. We investigated reward behaviour, learning ability and brain network connectivity in acute (3-7d) mild to moderate stroke patients (n = 28) and age-matched healthy controls (n = 26). Reward system activity was assessed using the Monetary Incentive Delay task (MID) during magnetoencephalography (MEG). Coherence analyses were used to demonstrate reward effects on brain functional network connectivity. The MID-task showed that stroke survivors had lower reward sensitivity and required greater monetary incentives to improve performance and showed deficits in learning improvement. MEG-analyses showed a reduced network connectivity in frontal and temporoparietal regions. All three effects (reduced reward sensitivity, reduced learning ability and altered cerebral connectivity) were found to be closely related and differed strongly from the healthy group. Our results reinforce the notion that acute stroke induces reward network dysfunction, leading to functional impairment of behavioural systems. These findings are representative of a general pattern in mild strokes and are independent of the specific lesion localisation. For stroke rehabilitation, these results represent an important point to identify the reduced learning capacity after stroke and to implement individualised recovery exercises accordingly.

Network structure-function coupling and neurocognition in cerebral small vessel disease

BACKGROUND

Cerebral small vessel disease is a leading cause of cognitive decline and vascular dementia. Small vessel disease pathology changes structural brain networks, but its impact on functional networks remains poorly understood. Structural and functional networks are closely coupled in healthy individuals, and decoupling is associated with clinical symptoms in other neurological conditions. We tested the hypothesis that structural-functional network coupling is related to neurocognitive outcomes in 262 small vessel disease patients.

METHODS

Participants underwent multimodal magnetic resonance imaging and cognitive assessment in 2011 and 2015. Structural connectivity networks were reconstructed using probabilistic diffusion tractography, while functional connectivity networks were estimated from resting-state functional magnetic resonance imaging. Structural and functional networks were then correlated to calculate a measure of structural-functional network coupling for each participant.

RESULTS

Lower whole-brain coupling was associated with reduced processing speed and greater apathy both cross-sectionally and longitudinally. In addition, coupling within the cognitive control network was associated with all cognitive outcomes, suggesting that neurocognitive outcomes in small vessel disease may be related to the functioning of this intrinsic connectivity network.

CONCLUSIONS

Our work demonstrates the influence of structural-functional connectivity network decoupling in small vessel disease symptomatology. Cognitive control network function may be investigated in future studies.

Altered Resting-State Brain Activity and Functional Connectivity in Post-Stroke Apathy: An fMRI Study

Apathy is a common neuropsychiatric disease after stroke and is linked to a lower quality of life while undergoing rehabilitation. However, it is still unknown what are the underlying neural mechanisms of apathy. This research aimed to explore differences in the cerebral activity and functional connectivity (FC) of subjects with post-stroke apathy and those without it. A total of 59 individuals with acute ischemic stroke and 29 healthy subjects with similar age, sex, and education were recruited. The Apathy Evaluation Scale (AES) was used to evaluate apathy at 3 months after stroke. Patients were split into two groups-PSA (n = 21) and nPSA (n = 38)-based on their diagnosis. The fractional amplitude of low-frequency fluctuation (fALFF) was used to measure cerebral activity, as well as region-of-interest to region-of-interest analysis to examine functional connectivity among apathy-related regions. Pearson correlation analysis between fALFF values and apathy severity was performed in this research. The values of fALFF in the left middle temporal regions, right anterior and middle cingulate regions, middle frontal region, and cuneus region differed significantly among groups. Pearson correlation analysis showed that the fALFF values in the left middle temporal region (p < 0.001, r = 0.66) and right cuneus (p < 0.001, r = 0.48) were positively correlated with AES scores in stroke patients, while fALFF values in the right anterior cingulate (p < 0.001, r = -0.61), right middle frontal gyrus (p < 0.001, r = -0.49), and middle cingulate gyrus (p = 0.04, r = -0.27) were negatively correlated with AES scores in stroke patients. These regions formed an apathy-related subnetwork, and functional connectivity analysis unveiled that altered connectivity was linked to PSA (p < 0.05). This research found that abnormalities in brain activity and FC in the left middle temporal region, right middle frontal region, right cuneate region, and right anterior and middle cingulate regions in stroke patients were associated with PSA, revealing a possible neural mechanism and providing new clues for the diagnosis and treatment of PSA.

Strengths and Weaknesses of the Vascular Apathy Hypothesis: A Narrative Review

The vascular apathy hypothesis states that cerebral small vessel disease (CSVD) can cause apathy, even when no other symptoms of CSVD are present. In order to examine this hypothesis, the objectives of this narrative review are to evaluate the evidence for a pathophysiological mechanism linking CSVD to apathy and to examine whether CSVD can be a sole cause of apathy. The nature of the CSVD-apathy relationship was evaluated using the Bradford Hill criteria as a method for research on the distinction between association and causation. Pathological, neuroimaging, and behavioral studies show that CSVD can cause lesions in the reward network, which causes an apathy syndrome. Studies in healthy older individuals, stroke patients and cognitively impaired persons consistently show an association between CSVD markers and apathy, although studies in older persons suffering from depression are inconclusive. A biological gradient is confirmed, as well as a temporal relationship, although the evidence for the latter is still weak. The specificity of this causal relationship is low given there often are other contributing factors in CSVD patients with apathy, particularly depression and cognitive deterioration. Differentiating between vascular apathy and other apathy syndromes on the basis of clinical features is not yet possible, while in-depth knowledge about differences in the prognosis and efficacy of treatment options for apathy caused by CSVD and other apathy syndromes is lacking. Since we cannot differentiate between etiologically different apathy syndromes as yet, it is premature to use the term vascular apathy which would suggest a distinct clinical apathy syndrome.

Does fluoxetine reduce apathetic and depressive symptoms after stroke? An analysis of the Efficacy oF Fluoxetine-a randomized Controlled Trial in Stroke trial data set

OBJECTIVE

Apathy is a common and disabling symptom after stroke with no proven treatments. Selective serotonin reuptake inhibitors are widely used to treat depressive symptoms post-stroke but whether they reduce apathetic symptoms is unknown. We determined the effect of fluoxetine on post-stroke apathy in a post hoc analysis of the EFFECTS (Efficacy oF Fluoxetine-a randomized Controlled Trial in Stroke) trial.

METHODS

EFFECTS enrolled patients ⩾18 years between 2 and 15 days after stroke onset. Participants were randomly assigned to receive oral fluoxetine 20 mg once daily or matching placebo for 6 months. The Montgomery-Åsberg Depression Rating Scale (MADRS) was administered at baseline and 6 months. Individual items on this scale were divided into those reflecting symptoms of apathy and depression. Symptoms were compared between fluoxetine and placebo groups.

RESULTS

Of 1500 participants enrolled, complete MADRS data were available for 1369. The modified intention-to-treat population included 681 patients in the fluoxetine group and 688 in the placebo group. Confirmatory factor analysis revealed that apathetic, depressive, and anhedonic symptoms were dissociable. Apathy scores increased in both fluoxetine and placebo groups (both p ⩽ 0.00001). In contrast, fluoxetine was associated with a reduction in depressive scores (p = 0.002).

CONCLUSION

Post-stroke apathetic and depressive symptoms respond differently to fluoxetine treatment. Our analysis suggests fluoxetine is ineffective in preventing post-stroke apathy.

Poststroke apathy: Major role of cognitive, depressive and neurological disorders over imaging determinants

Apathy occurs in approximately one third of people after stroke. Despite its frequency and functional consequences, the determinants of apathy have only been partially defined. The major difficulty lies in disentangling the reduction in activity due to apathy itself from those secondary to comorbidities, such as depression, sensorimotor deficits, and cognitive impairment. Here, we aimed to examine the prevalence of apathy, identify confounding sources of hypoactivity, and define its neuroimaging determinants using multivariate voxel lesion symptom-mapping (mVLSM) analyses. We assessed apathy in a subgroup (n = 325, mean age: 63.8 ± 10.5 years, 91.1% ischemic stroke) of the GRECogVASC cohort using the validated Behavioral Dysexecutive Syndrome Inventory, interpreted using GREFEX criteria, as well as confounding factors (depression, anxiety, severity of the neurological deficit, and gait disorders). mVLSM analysis was used to define neuroimaging determinants and was repeated after controlling for confounding factors. Apathy was present for 120 patients (36.9%, 95% CI: 31.7-42.2). Stepwise linear regression identified three factors associated with apathy: depressive symptoms (R² = .3, p = .0001), cognitive impairment (R² = .015, p = .02), and neurological deficit (R² = .110, p = .0001). Accordingly, only 9 (7.5%) patients had apathy without a confounding factor, i.e., isolated apathy. In conventional VLSM analysis, apathy was associated with a large number of subcortical lesions that were no longer considered after controlling for confounding factors. Strategic site analysis identified five regions associated with isolated apathy: the F3 orbitalis pars, left amygdala, left thalamus, left pallidum, and mesencephalon. mVLSM analysis identified four strategic sites associated with apathy: the right corticospinal tract (R² = .11; p = .0001), left frontostriatal tract (R² = .11; p = .0001), left thalamus (R² = .04; p = .0001), and left amygdala (R² = .01; p = .013). These regions remained significant after controlling for confounding factors but explained a lower amount of variance. These findings indicate that poststroke apathy is more strongly associated with depression, neurological deficit, and cognitive impairment than with stroke lesions locations, at least using VLSM analysis.

Early effect of thrombolysis on structural brain network organisation after anterior‐circulation stroke in the randomized WAKE‐UP trial

The symptoms of acute ischemic stroke can be attributed to disruption of the brain network architecture. Systemic thrombolysis is an effective treatment that preserves structural connectivity in the first days after the event. Its effect on the evolution of global network organisation is, however, not well understood. We present a secondary analysis of 269 patients from the randomized WAKE‐UP trial, comparing 127 imaging‐selected patients treated with alteplase with 142 controls who received placebo. We used indirect network mapping to quantify the impact of ischemic lesions on structural brain network organisation in terms of both global parameters of segregation and integration, and local disruption of individual connections. Network damage was estimated before randomization and again 22 to 36 h after administration of either alteplase or placebo. Evolution of structural network organisation was characterised by a loss in integration and gain in segregation, and this trajectory was attenuated by the administration of alteplase. Preserved brain network organization was associated with excellent functional outcome. Furthermore, the protective effect of alteplase was spatio‐topologically nonuniform, concentrating on a subnetwork of high centrality supported in the salvageable white matter surrounding the ischemic cores. This interplay between the location of the lesion, the pathophysiology of the ischemic penumbra, and the spatial embedding of the brain network explains the observed potential of thrombolysis to attenuate topological network damage early after stroke. Our findings might, in the future, lead to new brain network‐informed imaging biomarkers and improved prognostication in ischemic stroke.

Non-pharmacological intervention effects on apathy caused by central nervous system organic diseases: A network meta-analysis

BACKGROUND

To evaluate the best non-pharmacological interventions on apathy in patients with central nervous system (CNS) organic diseases.

METHODS

We searched PubMed, Web of Science, Embase, Cochrane Library electronic databases, China national knowledge infrastructure, Wanfang and Chinese biomedical literature database studies published from 2011 to May 29, 2021. A combination of subject words and free words were used for searching. Randomized controlled trials (RCTs) of non-pharmacological interventions for apathy in patients with central nervous organic disease were included. Two researchers independently identified the eligible RCTs and extracted information. The risk of bias within each individual trial was assessed using the Cocharane Collaboration's tool. Review Manager 5.4 and ADDIS 1.16.5 were used for data analysis.

RESULTS

A total of 5324 related studies were obtained in the initial screening, and final 8 RCTs including 334 patients were included, involving 4 non-pharmacological interventions of cognitive intervention, repetitive transcranial magnetic stimulation (rTMS), music therapy and occupational therapy. Direct comparison results showed that rTMS, cognitive intervention, and occupational therapy were superior to the conventional group (P < .05). Network Meta repeated rTMS, cognitive intervention was superior to the conventional group (P < .05), while the other groups did not differ from with the conventional group (P > .05). The order of superiority was rTMS, cognitive intervention, occupational therapy, music therapy, and conventional group.

CONCLUSION

Current evidence suggests that rTMS and cognitive interventions are more effective than the conventional intervention in improving apathy in patients with CNS organic diseases. It still needs more non-pharmacological intervention studies with high quality, larger sample sizes for further exploration.

Apathy exacerbates postural control impairments in stroke survivors: The potential effects of cognitive dual-task for improving postural control

Apathy is a stressor and debilitating common condition for both stroke survivors and their caregivers. However, its effects on the postural control of these patients have not yet been investigated. Improved postural stability through withdrawing attention from postural control by concurrent cognitive task (i.e. dual-task condition) has been reported previously, but the effect of apathy, as a confounding factor, remains unknown. This study aimed to examine the effects of apathy and dual-task condition on postural control of chronic stroke survivors from biomechanical and neurophysiological perspectives. Twenty non-apathetic stroke survivors, 20 apathetic stroke survivors, and 20 sex-, age-, weight-, and height-matched healthy subjects were assessed using different postural sway measures and electromyography activity of ankle and hip muscles while quietly standing on rigid and foam surfaces under single-task, easy dual-task, and difficult dual-task conditions. The results showed postural instability and neuromuscular stiffening of stroke survivors, particularly apathetic stroke survivors, compared with healthy controls as evidenced by significantly greater postural sway measures and increased co-contraction of ankle muscles as well as hip muscles. Notably, concurrently performing a cognitive task significantly reduced postural instability and neuromuscular stiffening in chronic stroke survivors even in those with apathy. In conclusion, apathy exacerbates postural control impairments in chronic stroke survivors promoting an inefficient conscious mode of postural control. It is recommended that distracting the attention away from postural control by performing a concurrent cognitive task can be considered an effective strategy while designing interventions for improving postural control in apathetic stroke survivors.

Comparison of Functional and Structural Neural Network Features in Older Adults With Depression With vs Without Apathy and Association With Response to Escitalopram: Secondary Analysis of a Nonrandomized Clinical Trial

IMPORTANCE

Apathy is prevalent among individuals with late-life depression and is associated with poor response to pharmacotherapy, including chronicity and disability. Elucidating brain networks associated with apathy and poor treatment outcomes can inform intervention development.

OBJECTIVES

To assess the brain network features of apathy among individuals with late-life depression and identify brain network abnormalities associated with poor antidepressant response.

DESIGN, SETTING, AND PARTICIPANTS

This secondary analysis of a single-group, open-label nonrandomized clinical trial of escitalopram conducted at an outpatient geriatric psychiatry clinic enrolled 40 adults aged 59 to 85 years with major depressive disorder from July 1, 2012, to July 31, 2019.

INTERVENTIONS

After a 2-week washout period, participants received escitalopram titrated to a target of 20 mg/d for 12 weeks.

MAIN OUTCOMES AND MEASURES

Baseline and posttreatment magnetic resonance imaging (MRI), clinical, and cognitive assessments were conducted. Functional MRI was used to map group differences in resting state functional connectivity (rsFC) of the salience network, and diffusion MRI connectometry was performed to evaluate pathway-level disruptions in structural connectivity. The Apathy Evaluation Scale was used to quantify apathy, and the Hamilton Depression Rating Scale (HAM-D) was used to quantify the primary outcome of depression severity.

RESULTS

Forty participants (26 women [65%]; mean [SD] age, 70.0 [6.6] years [range, 59-85 years]) with depression were included; 20 participants (50%) also had apathy. Relative to nonapathetic participants with depression, those with depression and apathy had lower rsFC of salience network seeds with the dorsolateral prefrontal cortex (DLPFC), premotor cortex, midcingulate cortex, and paracentral lobule and greater rsFC with the lateral temporal cortex and temporal pole (z score >2.7; Bonferroni-corrected threshold of P < .0125). Compared with participants without apathy, those with apathy had lower structural connectivity in the splenium, cingulum, and fronto-occipital fasciculus (t score >2.5; false discovery rate-corrected P = .02). Twenty-seven participants completed escitalopram treatment; 16 (59%) achieved remission (HAM-D score <10). Lower insula-DLPFC/midcingulate cortex rsFC was associated with less symptomatic improvement (HAM-D % change) (β [df] = 0.588 [26]; P = .001) and a higher likelihood of nonremission (odds ratio, 1.041 [95% CI, 1.003-1.081]; P = .04) after treatment and, in regression models, was a mediator of the association between baseline apathy and persistence of depression. Lower dorsal anterior cingulate-DLPFC/paracentral rsFC was associated with residual cognitive difficulties on measures of attention (β [df] = 0.445 [26]; P = .04) and executive function (β [df] = 0.384 [26]; P = .04).

CONCLUSIONS AND RELEVANCE

This study suggests that disturbances in connectivity between the salience network and other large-scale networks that support goal-directed behavior may give rise to apathy and may be associated with poor response of late-life depression to antidepressant pharmacotherapy. These network disturbances may serve as targets for novel interventions.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01728194.

Blood Pressure and Vascular Cognitive Impairment

High blood pressure (BP) is detrimental to brain health. High BP contributes to cognitive impairment and dementia through pathways independent of clinical stroke. Emerging evidence shows that the deleterious effect of high BP on cognition occurs across the life span, increasing the risk for early-onset and late-life dementia. The term vascular cognitive impairment includes cognitive disorders associated with cerebrovascular disease, regardless of the pathogenesis. This focused report is a narrative review that aims to summarize the epidemiology of BP and vascular cognitive impairment, including differences by sex, race, and ethnicity, as well as the management and reversibility of BP and vascular cognitive impairment. It also discusses knowledge gaps and future directions.

Determinants of Physical Activity at 90 Days After Acute Stroke or Transient Ischemic Attack in Patients With Home Discharge: A Pilot Study

The aim was to identify the barriers to achieving premorbid physical activity in patients with home discharge after acute minor stroke or transient ischemic attack. Fifty-six patients (median age, 72 years) were analyzed. We assessed total physical activity in the premorbid condition and at 90 days after onset using the International Physical Activity Questionnaire. The patients were divided into two groups according to changes in total physical activity until 90 days after onset: decreased activity (n = 16) and nondecreased activity (n = 40) groups. Outcome measures were examined at discharge. The decreased activity group took significantly longer to perform the timed up and go test (median, 7.19 vs. 6.52 s) and contained more apathetic patients (44% vs. 15%). Apathy at discharge (relative risk 6.05, 95% confidence interval [1.33, 27.6]) was a significant determinant of decreased physical activity. Apathy is a barrier to the restoration of premorbid physical activity in stroke survivors.

Magnetisation transfer imaging revealed microstructural changes related to apathy symptoms after ischaemic stroke

OBJECTIVES

Apathy after stroke is common and has a negative impact on functional recovery. Neuroimaging correlates of poststroke apathy remain unclear. We aimed to investigate microstructural changes associated with the severity of poststroke apathy symptoms.

METHODS

We assessed 67 patients with cerebral ischaemia who underwent magnetisation transfer brain imaging 12-15 months after stroke. We used magnetisation transfer ratio (MTR) to represent microstructural integrity. We performed whole-brain voxel-based analysis and subsequent region of interest analysis to investigate the association between MTR and symptoms of poststroke apathy. To assess apathy symptoms, we used clinician-reported version of the Apathy Evaluation Scale.

RESULTS

Voxel-based analysis showed the association between symptoms of apathy and decreased MTR in areas overlapping with structures located in both hemispheres: left thalamus, bilateral hippocampus, bilateral fornix/stria terminalis, right amygdala, splenium of the corpus callosum, the retrolenticular part of left internal capsule and left sagittal stratum. In the region of interest analysis, only lower MTR in right fornix/stria terminalis was associated with greater poststroke apathy symptoms in a multivariate logistic model (odds ratio: 1.25, 95% CI: 1.09-1.46, p = 0.003). These associations were independent of depressive symptoms.

CONCLUSION

Magnetisation transfer brain imaging 12-15 months after stroke revealed changes in microstructural integrity associated with apathy symptoms in brain areas related to processing emotional information and reward valuation.

Resting-State Functional Connectivity Signatures of Apathy in Community-Living Older Adults

Apathy predicts poor outcomes in older adults, and its underlying neural mechanism needs further investigation. We examined the association between symptoms of apathy and functional connectivity (FC) in older adults without stroke or dementia. Participants included 48 individuals (mean age = 70.90) living independently in the community, who underwent resting-state fMRI and completed the Apathy Evaluation Scale (AES). Seed-to-voxel analysis (cluster-level p-FDR <0.05, voxel threshold p < 0.001) tested the association between AES scores and the whole-brain FC of brain regions involved in reward- and salience-related processing. We found that AES scores were negatively associated with FC of the right insula cortex and right anterior temporal regions (124 voxels, t = −5.10) and FC of the left orbitofrontal cortex and anterior cingulate regions (160 voxels, t = −5.45), and were positively associated with FC of the left orbitofrontal cortex and left lateral prefrontal (282 voxels, t = 4.99) and anterior prefrontal (123 voxels, t = 4.52) regions. These findings suggest that apathy in older adults may reflect disruptions in neural connectivity involved in reward- and salience-related processing.

Apathy: Neurobiology, Assessment and Treatment

Apathy is a highly prevalent, disabling and treatment resistant syndrome. It is defined as a quantitative reduction of goal- directed activity in comparison to the patient’s previous level of in multiple dimensions including behavior/cognition, emotion and social interaction. It has been described in major depressive disorder, Alzheimer’s disease, frontotemporal dementia, Parkinson’s Disease, cerebrovascular disease, and vascular dementia, among others. This review will address the neuropsychology and associated neurobiological underpinnings of apathy in the above conditions, identify specific methods to assess apathy clinically, and review the literature on managing apathy across these various disorders.

Individual markers of cerebral small vessel disease and domain-specific quality of life deficits

BACKGROUND

Cerebral small vessel disease (SVD) leads to reduced quality of life (QOL), but the mechanisms underlying this relationship remain unknown. This study investigated multivariate relationships between radiological markers of SVD and domain-specific QOL deficits, as well as potential mediators, in patients with SVD.

METHODS

Clinical and neuroimaging measures were obtained from a pooled sample of 174 SVD patients from the St. George's Cognition and Neuroimaging in Stroke and PRESsure in established cERebral small VEssel disease studies. Lacunes, white matter hyperintensities, and microbleeds were defined as radiological markers of SVD and delineated using MRI. QOL was assessed using the Stroke-Specific Quality of Life Scale. Multivariate linear regression was used to determine whether SVD markers were associated with domain-specific QOL deficits. Significant associations were further investigated using mediation analysis to examine whether functional disability or cognition was potential mediators.

RESULTS

Multivariate regression analyses revealed that lacunes were associated with total QOL score (β = -8.22, p = .02), as well as reductions in mobility (β = -1.41, p = .008) and language-related subdomains (β = -0.69, p = .033). White matter hyperintensities and microbleeds showed univariate correlations with QOL, but these became nonsignificant during multivariate analyses. Mediation analyses revealed that functional disability, defined as reduced activities of daily living, and executive function, partially mediated the relationship between lacunes and total QOL, as well as mobility-related QOL, but not language-related QOL.

CONCLUSIONS

Lacunar infarcts have the most detrimental effect on QOL in SVD patients, particularly in the mobility and language-related subdomains. These effects may be partially explained by a reduction in activities of daily living. These results may inform targeted interventions to improve QOL in patients with SVD.

Apathy in small vessel cerebrovascular disease is associated with deficits in effort-based decision making

Patients with small vessel cerebrovascular disease frequently suffer from apathy, a debilitating neuropsychiatric syndrome, the underlying mechanisms of which remain to be established. Here we investigated the hypothesis that apathy is associated with disrupted decision making in effort-based decision making, and that these alterations are associated with abnormalities in the white matter network connecting brain regions that underpin such decisions. Eighty-two patients with MRI evidence of small vessel disease were assessed using a behavioural paradigm as well as diffusion weighted MRI. The decision-making task involved accepting or rejecting monetary rewards in return for performing different levels of physical effort (hand grip force). Choice data and reaction times were integrated into a drift diffusion model that framed decisions to accept or reject offers as stochastic processes approaching a decision boundary with a particular drift rate. Tract-based spatial statistics were used to assess the relationship between white matter tract integrity and apathy, while accounting for depression. Overall, patients with apathy accepted significantly fewer offers on this decision-making task. Notably, while apathetic patients were less responsive to low rewards, they were also significantly averse to investing in high effort. Significant reductions in white matter integrity were observed to be specifically related to apathy, but not to depression. These included pathways connecting brain regions previously implicated in effort-based decision making in healthy people. The drift rate to decision parameter was significantly associated with both apathy and altered white matter tracts, suggesting that both brain and behavioural changes in apathy are associated with this single parameter. On the other hand, depression was associated with an increase in the decision boundary, consistent with an increase in the amount of evidence required prior to making a decision. These findings demonstrate altered effort-based decision making for reward in apathy, and also highlight dissociable mechanisms underlying apathy and depression in small vessel disease. They provide clear potential brain and behavioural targets for future therapeutic interventions, as well as modelling parameters that can be used to measure the effects of treatment at the behavioural level.

Early apathetic, but not depressive, symptoms are associated with poor outcome after stroke

BACKGROUND AND PURPOSE

Depression and apathy are frequent neuropsychiatric disturbances after stroke and may appear together. Despite the overlap in symptoms between poststroke depression and apathy, these two syndromes might be associated with different prognoses and benefit from different treatments. We aimed to disentangle the relationship between early depressive and apathetic symptoms and outcome after stroke.

METHODS

Of 698 enrolled patients with ischemic stroke, we included 443 participants (median age = 69 years, 51% female) who underwent depressive and apathetic symptom assessment on Day 8 after stroke. We divided patients into four groups: without greater depressive and apathetic symptoms (Group 1), with only apathetic symptoms (Group 2), with only depressive symptoms (Group 3), and with both depressive and apathetic symptoms (Group 4).

RESULTS

After adjusting for age and stroke severity, Group 2 and Group 4 had an increased risk of poor 3-month outcome (odds ratio [OR] = 1.98, 95% confidence interval [CI] = 1.16-3.38, p = 0.01 and OR = 1.58, 95% CI = 1.24-2.01, p < 0.01, respectively). Group 2 and Group 4 also had an increased risk of poor 12-month outcome (OR = 3.85, 95% CI = 2.19-6.78, p < 0.01 and OR = 1.54, 95% CI = 1.22-1.96, p < 0.01, respectively) and mortality (hazard ratio [HR] = 2.76, 95% CI = 1.19-6.41, p = 0.02 and HR = 1.77, 95% CI = 1.32-2.38, p < 0.01, respectively). Compared with Group 1, Group 3 did not have an increased risk of unfavorable outcomes.

CONCLUSIONS

Early apathetic, but not depressive, symptoms are related to worse outcomes after stroke. Our study underscores the importance of recognizing apathetic symptoms independently from depressive symptoms.

Specific Dimensions of Depression Have Different Associations With Cognitive Decline in Older Adults With Type 2 Diabetes

OBJECTIVE

Depression is highly frequent in older adults with type 2 diabetes and is associated with cognitive impairment, yet little is known about how various depression dimensions differentially affect cognition. We investigated longitudinal associations of specific depression dimensions with cognitive decline.

RESEARCH DESIGN AND METHODS

Participants (N = 1,002) were from the Israel Diabetes and Cognitive Decline study, were ≥65 years of age, had type 2 diabetes, and were not experiencing dementia at baseline. Participants underwent a comprehensive neuropsychological battery at baseline and every 18 months thereafter, including domains of episodic memory, attention/working memory, semantic categorization/language, and executive function, and Z-scores of each domain were averaged and further normalized to calculate global cognition. Depression items from the 15-item Geriatric Depression Scale were measured at each visit and subcategorized into five dimensions: dysphoric mood, withdrawal-apathy-vigor (entitled apathy), anxiety, hopelessness, and memory complaint. Random coefficients models examined the association of depression dimensions with baseline and longitudinal cognitive functioning, adjusting for sociodemographics and baseline characteristics, including cardiovascular risk factors, physical activity, and use of diabetes medications.

RESULTS

In the fully adjusted model at baseline, all dimensions of depression, except for anxiety, were associated with some aspect of cognition (P values from 0.01 to <0.001). Longitudinally, greater apathy scores were associated with faster decline in executive function (P = 0.004), a result that withstood adjustment for multiple comparisons. Associations of other depression dimensions with cognitive decline were not significant (P > 0.01).

CONCLUSIONS

Apathy was associated with a faster cognitive decline in executive function. These findings highlight the heterogeneity of depression as a clinical construct rather than as a single entity and point to apathy as a specific risk factor for cognitive decline among older adults with type 2 diabetes.

Apathy after stroke: Diagnosis, mechanisms, consequences, and treatment

Apathy is a reduction in goal-directed activity in the cognitive, behavioral, emotional, or social domains of a patient’s life and occurs in one out of three patients after stroke. Despite this, apathy is clinically under-recognized and poorly understood. This overview provides a contemporary introduction to apathy in stroke for researchers and practitioners, covering topics including diagnosis, neurobiological mechanisms, associated consequences, and potential treatments for apathy. Apathy is often misdiagnosed as other post-stroke conditions such as depression. Accurate differential diagnosis of apathy, which manifests as reductions in initiative, and depression, which manifests as negative emotionality, is important as it informs prognosis. Research on the neurobiology of apathy suggests that there are few consistent associations between stroke lesion location and the development of apathy. These may be resolved by adopting a network neuroscience approach, which models apathy as a pathology arising from structural or functional damage to brain networks underlying motivated behavior. Importantly, networks can be affected by physiological changes related to stroke, including the acute infarct but also diaschisis and neurodegeneration. Aside from neurobiological changes, apathy is also associated with other negative outcome measures such as functional disability, cognitive impairment, and emotional distress, suggesting that apathy is indicative of a worse prognosis following stroke. Unfortunately, high-quality trials aimed at treating apathy are scarce. Antidepressants may have limited effects on apathy. Acetylcholine and dopamine pharmacotherapy, behavioral interventions, and transcranial magnetic stimulation may be more promising avenues for treatment.

Apathy, but not depression, predicts all-cause dementia in cerebral small vessel disease

OBJECTIVE

To determine whether apathy or depression predicts all-cause dementia in small vessel disease (SVD) patients.

METHODS

Analyses used two prospective cohort studies of SVD: St. George's Cognition and Neuroimaging in Stroke (SCANS; n=121) and Radboud University Nijmegen Diffusion Tensor and Magnetic Resonance Cohort (RUN DMC; n=352). Multivariate Cox regressions were used to predict dementia using baseline apathy and depression scores in both datasets. Change in apathy and depression was used to predict dementia in a subset of 104 participants with longitudinal data from SCANS. All models were controlled for age, education and cognitive function.

RESULTS

Baseline apathy scores predicted dementia in SCANS (HR 1.49, 95% CI 1.05 to 2.11, p=0.024) and RUN DMC (HR 1.05, 95% CI 1.01 to 1.09, p=0.007). Increasing apathy was associated with dementia in SCANS (HR 1.53, 95% CI 1.08 to 2.17, p=0.017). In contrast, baseline depression and change in depression did not predict dementia in either dataset. Including apathy in predictive models of dementia improved model fit.

CONCLUSIONS

Apathy, but not depression, may be a prodromal symptom of dementia in SVD, and may be useful in identifying at-risk individuals.

Network Efficiency Mediates the Relationship Between Vascular Burden and Cognitive Impairment: A Diffusion Tensor Imaging Study in UK Biobank

Background and Purpose- Cerebrovascular disease contributes to age-related cognitive decline, but the mechanisms underlying this phenomenon remain incompletely understood. We hypothesized that vascular risk factors would lead to cognitive impairment through the disruption of brain white matter network efficiency. Methods- Participants were 19 346 neurologically healthy individuals from UK Biobank that underwent diffusion MRI and cognitive testing (mean age=62.6). Global efficiency, a measure of network integration, was calculated from white matter networks constructed using deterministic diffusion tractography. First, we determined whether demographics (age, sex, ethnicity, socioeconomic status, and education), vascular risk factors (hypertension, hypercholesterolemia, diabetes mellitus, smoking, body mass index), and white matter hyperintensities were related to global efficiency using multivariate linear regression. Next, we used structural equation modeling to model a multiple regression. The dependent variable was a latent cognition variable using all cognitive data, while independent variables were a latent factor including all vascular risk factors (vascular burden), demographic variables, white matter hyperintensities, and global efficiency. Finally, we used mediation analysis to determine whether global efficiency explained the relationship between vascular burden and cognition. Results- Hypertension and diabetes mellitus were consistently associated with reduced global efficiency even after controlling for white matter hyperintensities. Structural equation models revealed that vascular burden was associated with cognition (P=0.023), but not after adding global efficiency to the model (P=0.09), suggesting a mediation effect. Mediation analysis revealed a significant indirect effect of global efficiency on cognition through vascular burden (P<0.001), suggesting a partial mediation effect. Conclusions- Vascular burden is associated with reduced global efficiency and cognitive impairment in the general population. Network efficiency partially mediates the relationship between vascular burden and cognition. This suggests that treating specific risk factors may prevent reductions in brain network efficiency and preserve cognitive functioning in the aging population.