Structural and microstructural thalamocortical network disruption in sporadic behavioural variant frontotemporal dementia.

BACKGROUND: Using multi-block methods we combined multimodal neuroimaging metrics of thalamic morphology, thalamic white matter tract diffusion metrics, and cortical thickness to examine changes in behavioural variant frontotemporal dementia. (bvFTD). METHOD: Twenty-three patients with sporadic bvFTD and 24 healthy controls underwent structural and diffusion MRI scans. Clinical severity was assessed using the Clinical Dementia Rating scale and behavioural severity using the Frontal Behaviour Inventory by patient caregivers. Thalamic volumes were manually segmented. Anterior and posterior thalamic radiation fractional anisotropy and mean diffusivity were extracted using Tract-Based Spatial Statistics. Finally, cortical thickness was assessed using Freesurfer. We used shape analyses, diffusion measures, and cortical thickness as features in sparse multi-block partial least squares (PLS) discriminatory analyses to classify participants within bvFTD or healthy control groups. Sparsity was tuned with five-fold cross-validation repeated 10 times. Final model fit was assessed using permutation testing. Additionally, sparse multi-block PLS was used to examine associations between imaging features and measures of dementia severity. RESULTS: Bilateral anterior-dorsal thalamic atrophy, reduction in mean diffusivity of thalamic projections, and frontotemporal cortical thinning, were the main features predicting bvFTD group membership. The model had a sensitivity of 96%, specificity of 68%, and was statistically significant using permutation testing (p = 0.012). For measures of dementia severity, we found similar involvement of regional thalamic and cortical areas as in discrimination analyses, although more extensive thalamo-cortical white matter metric changes. CONCLUSIONS: Using multimodal neuroimaging, we demonstrate combined structural network dysfunction of anterior cortical regions, cortical-thalamic projections, and anterior thalamic regions in sporadic bvFTD.

Reduced SMA-M1 connectivity in older than younger adults measured using dual-site TMS.

With advancing age comes a decline in voluntary movement control. Growing evidence suggests that an age-related decline in effective connectivity between the supplementary motor area and primary motor cortex (SMA-M1) might play a role in an age-related decline of bilateral motor control. Dual-site transcranial magnetic stimulation (TMS) can be used to measure SMA-M1 effective connectivity. In the current study, we aimed to (1) replicate previous dual-site TMS research showing reduced SMA-M1 connectivity in older than younger adults and (2) examine whether SMA-M1 connectivity is associated with bilateral motor control in independent samples of younger (n = 30) and older adults (n = 30). SMA-M1 connectivity was measured using dual-site TMS with interstimulus intervals of 6, 7 and 8 ms, and bilateral motor control was measured using the Purdue Pegboard, Four Square Step Test and the Timed Up and Go task. Findings from this study showed that SMA-M1 connectivity was reduced in older than in younger adults, suggesting that the direct excitatory connections between SMA and M1 had reduced efficacy in older than younger adults. Furthermore, greater SMA-M1 connectivity was associated with better bimanual motor control in older adults. Thus, SMA-M1 connectivity in older adults might underpin, in part, the age-related decline in bilateral motor control. These findings contribute to our understanding of age-related declines in motor control and provide a physiological basis for the development of interventions to improve bimanual and bilateral motor control.

Structural and functional neuroimaging changes associated with cognitive impairment and dementia in Parkinson's disease.

This study seeks a better understanding of possible pathophysiological mechanisms associated with cognitive impairment and dementia in Parkinson's disease using structural and functional MRI. We investigated resting-state functional connectivity of important subdivisions of the caudate nucleus, putamen and thalamus, and also how the morphology of these structures are impacted in the disorder. We found cognitively unimpaired Parkinson's disease subjects (n = 33), compared to controls (n = 26), display increased functional connectivity of the dorsal caudate, anterior putamen and mediodorsal thalamic subdivisions with areas across the frontal lobe, as well as reduced functional connectivity of the dorsal caudate with posterior cortical and cerebellar regions. Compared to cognitively unimpaired subjects, those with mild cognitive impairment (n = 22) demonstrated reduced functional connectivity of the mediodorsal thalamus with the paracingulate cortex, while also demonstrating increased functional connectivity of the mediodorsal thalamus with the posterior cingulate cortex, compared to subjects with dementia (n = 17). Extensive volumetric and surface-based deflation was found in subjects with dementia compared to cognitively unimpaired Parkinson's disease participants and controls. Our research suggests that structures within basal ganglia-thalamocortical circuits are implicated in cognitive impairment and dementia in Parkinson's disease, with cognitive impairment and dementia associated with a breakdown in functional connectivity of the mediodorsal thalamus with para- and posterior cingulate regions of the brain respectively.

Development of a behaviour change workplace-based intervention to improve nurses' eating and physical activity.

BACKGROUND: There is a critical need for an intervention to improve nurses' eating and physical activity behaviours. As nurses spend a substantial proportion of their waking hours at work, concerted efforts to deliver such interventions in the workplace is growing. This study formed part of a multiphase programme of research that aimed to systematically develop an evidence-based and theory-informed workplace intervention to promote changes in eating and physical activity among nurses. METHODS: The intervention was developed iteratively, in line with Medical Research Council complex intervention guidelines. It involved four activities: (1) identifying the evidence base, (2) understanding the determinants of nurses' eating and physical activity behaviour change through theory-based qualitative interviews and survey, (3) identifying intervention options using the Behaviour Change Wheel, and (4) specifying intervention content and implementation options using a taxonomy of behaviour change techniques. RESULTS: Data from 13 randomised controlled trials indicated that workplace-based behaviour change interventions targeted to this population are effective in changing behaviour. The evidence base was, however, limited in quantity and quality. Nurses' beliefs about important factors determining their eating and physical activity behaviour were identified across 16 qualitative interviews and 245 survey responses, and key determinants included environmental context and resources, behavioural regulation, emotion, beliefs about consequences, knowledge and optimism. Based on these findings, 22 behaviour change techniques suitable for targeting the identified determinants were identified and combined into a potential workplace intervention. CONCLUSIONS: An evidence-based and theory-informed intervention tailored to the target population and setting has been explicitly conceptualised using a systematic approach. The proposed intervention addresses previous evidence gaps for the user population of nurses. Further to this, such an intervention, if implemented, has the potential to impact nurses' eating and physical activity behaviours and in turn, the health of nurses and the quality of healthcare delivery.

A survey of general practitioner's opinion on the proposal to introduce 'treat and referral' into the Irish emergency medical service.

BACKGROUND: The introduction of treat and referral by ambulance practitioners is under active consideration in Ireland. The Irish ambulance services have traditionally transported all patients following an emergency (112/999) call to an emergency department. The introduction of treat and referral will present a significant care pathway change. AIMS: To engage GPs in relation to the proposed introduction of treat and referral. METHODS: A postal survey of 50 general practices in the southeast of Ireland was completed in 2019 to identify their opinion on the introduction of treat and referral. Descriptive statistics were calculated, and Pearson's chi-square tests were used to identify statistically significant differences among GP cohorts. RESULTS: A 78% response rate was achieved. Respondents indicated that informal treat and referral was practised by 40% of GPs. A significant majority of GPs indicated that their patients with diabetes or epilepsy would benefit from treat and referral and were happy for paramedics to make appointments posthypoglycaemia or seizure. There was no clear consensus in relation to confining treat and referral to adults only. Barriers to the implementation of treat and referral were a significant issue for GPs. CONCLUSIONS: GPs are in the main supportive of the introduction of treat and referral; however, they have identified several barriers that may inhibit successful introduction. Importantly, a GP appointment within 48 h does not appear to be a barrier. The adequacy of the working relationships between GPs and the ambulance service and its practitioners appears to have reduced since 2006, which is concerning.

Morphometric in vivo evidence of thalamic atrophy correlated with cognitive and motor dysfunction in Huntington's disease: The IMAGE-HD study.

In Huntington's disease (HD), neurodegeneration causes progressive atrophy to the striatum, cortical areas, and white matter tracts - components of corticostriatal circuitry. Such processes may affect the thalamus, a key circuit node. We investigated whether differences in dorsal thalamic morphology were detectable in HD, and whether thalamic atrophy was associated with neurocognitive, neuropsychiatric and motor dysfunction. Magnetic resonance imaging scans and clinical outcome measures were obtained from 34 presymptomatic HD (pre-HD), 29 early symptomatic HD (symp-HD), and 26 healthy control individuals who participated in the IMAGE-HD study. Manual region of interest (ROI) segmentation was conducted to measure dorsal thalamic volume, and thalamic ROI underwent shape analysis using the spherical harmonic point distribution method. The symp-HD group had significant thalamic volumetric reduction and global shape deflation, indicative of atrophy, compared to pre-HD and control groups. Thalamic atrophy significantly predicted neurocognitive and motor dysfunction within the symp-HD group only. Thalamic morphology differentiates symp-HD from pre-HD and healthy individuals. Thalamic changes may be one of the structural bases (endomorphotypes), of the endophenotypic neurocognitive and motor manifestations of disease. Future research should continue to investigate the thalamus as a potential in vivo biomarker of disease progression in HD.

Improved prediction equations for estimating height in adults from ethnically diverse backgrounds.

BACKGROUND & AIMS: When body height cannot be measured, it can be predicted from ulna length (UL). However, commonly used published prediction equations may not provide useful estimates in adults from all ethnicities. This study aimed to evaluate the relationship between UL and height in adults from diverse ethnic groups and to consider whether this can be used to provide useful prediction equations for height in practice. METHODS: Standing height and UL were measured in 542 adults at seven UK locations. Ethnicity was self-defined using UK Census 2011 categories. Data were modelled to give two groups of height prediction equations based on UL, sex and ethnicity and these were tested against an independent dataset (n = 180). RESULTS: UL and height were significantly associated overall and in all groups except one with few participants (P = 0.059). The new equations yielded predicted height (Hp) that was closer to measured height in the Asian and Black subgroups of the independent population than the Malnutrition Universal Screening Tool (MUST) equations. For Asian men, (Hp (cm) = 3.26 UL (cm) + 83.58), mean difference from measured (95% confidence intervals) was -0.6 (-2.4, +1.2); Asian women, (Hp = 3.26 UL + 77.62), mean difference +0.5 (-1.4, 2.4) cm. For Black men, Hp = 3.14 UL + 85.80, -0.4 (-2.4, 1.7); Black women, Hp = 3.14 UL + 79.55, -0.8 (-2.8, 1.2). These differences were not statistically significant while predictions from MUST equations were significantly different from measured height. CONCLUSIONS: The new prediction equations provide an alternative for estimating height in adults from Asian and Black groups and give mean predicted values that are closer to measured height than MUST equations.

Multidisciplinary rehabilitation reduces hypothalamic grey matter volume loss in individuals with preclinical Huntington's disease: A nine-month pilot study.

BACKGROUND: Hypothalamic pathology is a well-documented feature of Huntington's disease (HD) and is believed to contribute to circadian rhythm and habitual sleep disturbances. Currently, no therapies exist to combat hypothalamic changes, nor circadian rhythm and habitual sleep disturbances in HD. OBJECTIVE: To evaluate the effects of multidisciplinary rehabilitation on hypothalamic volume, brain-derived neurotrophic factor (BDNF), circadian rhythm and habitual sleep in individuals with preclinical HD. METHODS: Eighteen individuals with HD (ten premanifest and eight prodromal) undertook a nine-month multidisciplinary rehabilitation intervention (intervention group), which included exercise, cognitive and dual task training and social events, and were compared to a community sample of eleven individuals with premanifest HD receiving no intervention (control group). Hypothalamic volume, serum BDNF, salivary cortisol and melatonin concentrations, subjective sleep quality, daytime somnolence, habitual sleep-wake patterns, stress and anxiety and depression symptomatology were evaluated. RESULTS: Hypothalamus grey matter volume loss was significantly attenuated in the intervention group compared to the control group after controlling for age, gender, Unified Huntington's Disease Rating Scale-Total Motor Score and number of cytosine-adenine-guanine repeats. Serum BDNF levels were maintained in the intervention group, but decreased in the control group following the study period. Both groups exhibited decreases in cortisol and melatonin concentrations. No changes were observed in sleep or mood outcomes. CONCLUSIONS: This exploratory study provides evidence that multidisciplinary rehabilitation can reduce hypothalamic volume loss and maintain peripheral BDNF levels in individuals with preclinical HD but may not impact on circadian rhythm. Larger, randomised controlled trials are required to confirm these findings.

Stakeholder opinion on the proposal to introduce 'treat and referral' into the Irish emergency medical service.

BACKGROUND: The Irish ambulance services have traditionally transported all patients following an emergency (112/999) call, regardless of acuity, to an emergency department (ED). A proposal to introduce Treat and Referral, an established care pathway in some jurisdictions, is under active consideration in Ireland. This will present a significant change. Stakeholder engagement is recognised as an essential component of management of such change. This study has conducted a multicentre, cross-sectional survey exploring opinions on the introduction of Treat and Referral among key Irish stakeholders; consultants in emergency medicine, paramedics and advanced paramedics. METHODS: Public-sector consultants in emergency medicine (EM), registered paramedics and advanced paramedics, in Ireland at the time of the study, were invited to complete an on-line survey. RESULTS: A significant finding was that 90% of both cohorts (EM consultants and registered paramedic practitioners) support written after-care instructions being given to referred patients, that > 83% agree that Treat and Referral will reduce unnecessary ambulance journeys and that 70% are in favour of their own family member being offered Treat and Referral. Consensus was reached between respondents that Treat and Referral would improve care and increase clinical judgement of practitioners. Differences were identified in relation to the increased availability of ambulances locally, that only adults should be included, and that research was required to extend Treat and Referral beyond the index conditions. There was no consensus on whether general practitioners (GPs) should be directly informed. CONCLUSIONS: This study identified that the Irish healthcare practitioners surveyed are supportive of the introduction of Treat and Referral into Ireland. It also affords healthcare policymakers the opportunity to address the concerns raised, in particular the clinical level which will be targeted for inclusion in this extended scope of practice.

Increased functional connectivity of thalamic subdivisions in patients with Parkinson's disease.

Parkinson's disease (PD) affects 2-3% of the population over the age of 65 with loss of dopaminergic neurons in the substantia nigra impacting the functioning of basal ganglia-thalamocortical circuits. The precise role played by the thalamus is unknown, despite its critical role in the functioning of the cerebral cortex, and the abnormal neuronal activity of the structure in PD. Our objective was to more clearly elucidate how functional connectivity and morphology of the thalamus are impacted in PD (n = 32) compared to Controls (n = 20). To investigate functional connectivity of the thalamus we subdivided the structure into two important regions-of-interest, the first with putative connections to the motor cortices and the second with putative connections to prefrontal cortices. We then investigated potential differences in the size and shape of the thalamus in PD, and how morphology and functional connectivity relate to clinical variables. Our data demonstrate that PD is associated with increases in functional connectivity between motor subdivisions of the thalamus and the supplementary motor area, and between prefrontal thalamic subdivisions and nuclei of the basal ganglia, anterior and dorsolateral prefrontal cortices, as well as the anterior and paracingulate gyri. These results suggest that PD is associated with increased functional connectivity of subdivisions of the thalamus which may be indicative alterations to basal ganglia-thalamocortical circuitry.

Reviewing the preclinical curriculum in a Problem Based Learning driven medical program: challenges and strategies.

This article was migrated. The article was marked as recommended. In order for medical curricula to remain progressive and contemporary, continuous review is critical to ensure that the learners are directed to achieve the intended goals and become workforce ready. We developed a framework for continuous curriculum review at the School of Medicine Fremantle (The University of Notre Dame Australia), taking the key aspects of a curriculum review process into consideration. In planning and implementing the review process we identified several challenges, including management of metadata, work load on staff members, and evaluation. These challenges were addressed successfully by applying necessary strategies using limited resources. The framework we have developed provides a guide to key stakeholders who are involved in medical curriculum review and development.

Supporting nurses to adopt healthy eating behaviours.

Nurses have a central role in health education and promotion, particularly with regard to supporting individuals to optimise their nutritional intake and engage in healthy eating behaviours. However, high rates of obesity, unhealthy eating behaviours and low levels of physical activity have been found among nurses. Nursing is a challenging profession, and a high workload, a lack of resources and shift work may affect nurses' ability to adopt healthy lifestyles. Supporting nurses to improve aspects of their eating behaviours, such as the nutritional value, timing and frequency of meals, can have a positive effect on their health which, in turn, may enhance their ability to care for patients. Although there is much literature available on the benefits of healthy eating, there is a lack of practical guidance for nurses on how to enhance their nutritional intake. This article uses a case study to examine the occupational and personal factors that may affect nurses' ability to engage in healthy eating behaviours, and identifies how healthcare organisations and individual nurses can use a behavioural change approach to optimise nutritional intake.

Regional structural hypo- and hyperconnectivity of frontal-striatal and frontal-thalamic pathways in behavioral variant frontotemporal dementia.

Behavioral variant frontotemporal dementia (bvFTD) has been predominantly considered as a frontotemporal cortical disease, with limited direct investigation of frontal-subcortical connections. We aim to characterize the grey and white matter components of frontal-thalamic and frontal-striatal circuits in bvFTD. Twenty-four patients with bvFTD and 24 healthy controls underwent morphological and diffusion imaging. Subcortical structures were manually segmented according to published protocols. Probabilistic pathways were reconstructed separately from the dorsolateral, orbitofrontal and medial prefrontal cortex to the striatum and thalamus. Patients with bvFTD had smaller cortical and subcortical volumes, lower fractional anisotropy, and higher mean diffusivity metrics, which is consistent with disruptions in frontal-striatal-thalamic pathways. Unexpectedly, regional volumes of the striatum and thalamus connected to the medial prefrontal cortex were significantly larger in bvFTD (by 135% in the striatum, p = .032, and 217% in the thalamus, p = .004), despite smaller dorsolateral prefrontal cortex connected regional volumes (by 67% in the striatum, p = .002, and 65% in the thalamus, p = .020), and inconsistent changes in orbitofrontal cortex connected regions. These unanticipated findings may represent compensatory or maladaptive remodeling in bvFTD networks. Comparisons are made to other neuropsychiatric disorders suggesting a common mechanism of changes in frontal-subcortical networks; however, longitudinal studies are necessary to test this hypothesis.

Morphometric analysis of thalamic volume in progressive supranuclear palsy: In vivo evidence of regionally specific bilateral thalamic atrophy.

We investigated whether differences were detectable in the volume and shape of the dorsal thalamus on magnetic resonance imaging in patients with progressive supranuclear palsy (PSP). Manual segmentation of the left and right thalami on magnetic resonance imaging scans occurred in 22 patients with clinically diagnosed PSP and 23 healthy controls; thalamic volumes (left, right, total) were calculated. Between group differences were explored by multivariate analysis of co-variance, using age and intracranial volume as covariates. Analysis of the shape of the thalamus was performed using the spherical harmonic point distribution method software package. Patients with PSP were found to have significant bilateral thalamic atrophy on magnetic resonance imaging; there was significant shape deflation over the anterior-lateral and anterior-ventral surfaces bilaterally, and over the right caudal thalamus. Recognizing decreased thalamic morphology in PSP patients in vivo may be an important component of an ensemble of diagnostic biomarkers in the future, particularly given the difficulty of distinguishing PSP from other Parkinsonian conditions early in the disease course.

Understanding perceived determinants of nurses' eating and physical activity behaviour: a theory-informed qualitative interview study.

BACKGROUND: Unhealthy eating and physical activity behaviours are common among nurses but little is known about determinants of eating and physical activity behaviour in this population. The present study used a theoretical framework which summarises the many possible determinants of different health behaviours (the Theoretical Domains Framework; TDF) to systematically explore the most salient determinants of unhealthy eating and physical activity behaviour in hospital-based nurses. METHODS: Semi-structured qualitative interviews based on the TDF were conducted with nurses (n = 16) to explore factors that behavioural theories suggest may influence nurses' eating and physical activity behaviour. Important determinants of the target behaviours were identified using both inductive coding (of categories emerging from the data) and deductive coding (of categories derived from the TDF) of the qualitative data. RESULTS: Thirteen of the fourteen domains in the TDF were found to influence nurses' eating and physical activity behaviour. Within these domains, important barriers to engaging in healthy eating and physical activity behaviour were shift work, fatigue, stress, beliefs about negative consequences, the behaviours of family and friends and lack of planning. Important factors reported to enable engagement with healthy eating and physical activity behaviours were beliefs about benefits, the use of self-monitoring strategies, support from work colleagues, confidence, shift work, awareness of useful guidelines and strategies, good mood, future holidays and receiving compliments. CONCLUSIONS: This study used a theory-informed approach by applying the TDF to identify the key perceived determinants of nurses' eating and physical activity behaviour. The findings suggest that future efforts to change nurses' eating and physical activity behaviours should consider targeting a broad range of environmental, interpersonal and intrapersonal level factors, consistent with a socio-ecological perspective.

Extended "Timed Up and Go" assessment as a clinical indicator of cognitive state in Parkinson's disease.

OBJECTIVE: To evaluate a modified extended Timed Up and Go (extended-TUG) assessment against a panel of validated clinical assessments, as an indicator of Parkinson's disease (PD) severity and cognitive impairment. METHODS: Eighty-seven participants with idiopathic PD were sequentially recruited from a Movement Disorders Clinic. An extended-TUG assessment was employed which required participants to stand from a seated position, walk in a straight line for 7m, turn 180° and then return to the start, in a seated position. The extended-TUG assessment duration was correlated to a panel of clinical assessments, including the Unified Parkinson's Disease Rating Scale (MDS-UPDRS), Quality of Life (PDQ-39), Scales for Outcomes in Parkinson's Disease (SCOPA-Cog), revised Addenbrooke's Cognitive Index (ACE-R) and Barratt's Impulsivity Scale 11 (BIS-11). RESULTS: Extended-TUG time was significantly correlated to MDS-UPDRS III score and to SCOPA-Cog, ACE-R (p<0.001) and PDQ-39 scores (p<0.01). Generalized linear models determined the extended-TUG to be a sole variable in predicting ACE-R or SCOPA-Cog scores. Patients in the fastest extended-TUG tertile were predicted to perform 8.3 and 13.4 points better in the SCOPA-Cog and ACE-R assessments, respectively, than the slowest group. Patients who exceeded the dementia cut-off scores with these instruments exhibited significantly longer extended-TUG times. CONCLUSIONS: Extended-TUG performance appears to be a useful indicator of cognition as well as motor function and quality of life in PD, and warrants further evaluation as a first line assessment tool to monitor disease severity and response to treatment. Poor extended-TUG performance may identify patients without overt cognitive impairment form whom cognitive assessment is needed.

Neuroimaging in psychiatry: an update on neuroimaging in the clinical setting.

OBJECTIVE: We offered guidance on the role of structural and functional neuroimaging modalities for the general psychiatrist and for trainees in the clinical setting. METHODS: We outlined the utility of neuroimaging modalities in the clinical setting, specifically with a view to understanding the pathophysiology of manifestations of disease. RESULTS: Both structural and functional neuroimaging modalities have a clear role in diagnostic evaluation in the spectrum of neurodegenerative disorders. CONCLUSIONS: Whilst the role of neuroimaging in patients with mood, anxiety and psychotic disorders is less clear, structural and functional imaging modalities have utility in the clinical setting in the form of diagnostic refinement and in understanding the pathophysiology of disorders, towards explaining manifestations and planning treatment.

No additive effect of cannabis on cognition in schizophrenia.

BACKGROUND: We aimed to examine the association between lifetime cannabis use and estimates of both premorbid and current cognitive function in psychotic disorders in an Australian cohort. METHODS: In an Australian multicenter cohort, 1237 participants with an established ICD-10 diagnosis of psychotic disorder were categorised according to history of lifetime cannabis use (non-users, n=354; cannabis users, n=221; cannabis dependency, n=662). Groups were analyzed according to available indices of cognitive ability: the National Adult Reading Test - Revised (NART-R) for ability prior to illness onset; and the Digit Symbol Coding Test (DSCT) for current ability. Two-way analysis of variance was conducted without any covariate, followed by a two-way analysis of covariance (using age, age at onset of psychiatric illness, premorbid IQ and the Socio-Economic Index for Areas (SEIFA) rankings). RESULTS: Whilst there appeared to be a significant association between cannabis use and mean DSCT (higher DSCT scores in cannabis using groups) F(2,1080)=9.478, p<0.001, η2=0.017), once covariates were used in the analysis there were no significant differences between groups in mean DSCT scores (F(2,1011)=0.929, p=0.395, η2=0.002). Similarly there were no differences between groups in mean NART scores once, age, age at illness onset and SEIFA rankings were used as covariates (F(2,1032)=1.617, p=0.199, η2=0.003). CONCLUSIONS: Confounding variables underpin the association between cannabis use and cognitive function in psychotic disorders. Taken together, it would appear that cannabis use or dependence has no additive effect on cognitive dysfunction in these disorders.

The thalamus as a putative biomarker in neurodegenerative disorders.

OBJECTIVE: This review provides a brief account of the clinically relevant functional neuroanatomy of the thalamus, before considering the utility of various modalities utilized to image the thalamus and technical challenges therein, and going on to provide an overview of studies utilizing structural imaging techniques to map thalamic morphology in the spectrum of neurodegenerative disorders. METHODS: A systematic search was conducted for peer-reviewed studies involving structural neuroimaging modalities investigating the morphology (shape and/or size) of the thalamus in the spectrum of neurodegenerative disorders. RESULTS: While the precise role of the thalamus in the healthy brain remains unclear, there is a large body of knowledge accumulating which defines more precisely its functional connectivity within the connectome, and a burgeoning literature implicating its involvement in neurodegenerative disorders. It is proposed that correlation of clinical features with thalamic morphology (as a component of a quantifiable subcortical connectome) will provide a better understanding of neuropsychiatric dysfunction in various neurodegenerative disorders, potentially yielding clinically useful endophenotypes and disease biomarkers. CONCLUSION: Thalamic biomarkers in the neurodegenerative disorders have great potential to provide clinically meaningful knowledge regarding not only disease onset and progression but may yield targets of and perhaps a way of gauging response to future disease-modifying modalities.