Subthalamic nucleus shows opposite functional connectivity pattern in Huntington's and Parkinson's disease.

Huntington's and Parkinson's disease are two movement disorders representing mainly opposite states of the basal ganglia inhibitory function. Despite being an integral part of the cortico-subcortico-cortical circuitry, the subthalamic nucleus function has been studied at the level of detail required to isolate its signal only through invasive studies in Huntington's and Parkinson's disease. Here, we tested whether the subthalamic nucleus exhibited opposite functional signatures in early Huntington's and Parkinson's disease. We included both movement disorders in the same whole-brain imaging study, and leveraged ultra-high-field 7T MRI to achieve the very fine resolution needed to investigate the smallest of the basal ganglia nuclei. Eleven of the 12 Huntington's disease carriers were recruited at a premanifest stage, while 16 of the 18 Parkinson's disease patients only exhibited unilateral motor symptoms (15 were at Stage I of Hoehn and Yahr off medication). Our group comparison interaction analyses, including 24 healthy controls, revealed a differential effect of Huntington's and Parkinson's disease on the functional connectivity at rest of the subthalamic nucleus within the sensorimotor network, i.e. an opposite effect compared with their respective age-matched healthy control groups. This differential impact in the subthalamic nucleus included an area precisely corresponding to the deep brain stimulation 'sweet spot'-the area with maximum overall efficacy-in Parkinson's disease. Importantly, the severity of deviation away from controls' resting-state values in the subthalamic nucleus was associated with the severity of motor and cognitive symptoms in both diseases, despite functional connectivity going in opposite directions in each disorder. We also observed an altered, opposite impact of Huntington's and Parkinson's disease on functional connectivity within the sensorimotor cortex, once again with relevant associations with clinical symptoms. The high resolution offered by the 7T scanner has thus made it possible to explore the complex interplay between the disease effects and their contribution on the subthalamic nucleus, and sensorimotor cortex. Taken altogether, these findings reveal for the first time non-invasively in humans a differential, clinically meaningful impact of the pathophysiological process of these two movement disorders on the overall sensorimotor functional connection of the subthalamic nucleus and sensorimotor cortex.

Decision-making capacity in older medical in-patients: frequency of assessment and rates of incapacity by decision-type and underlying brain/mind impairment.

BACKGROUND: Hospital clinicians find mental capacity assessment challenging and may lack the necessary skills. Given high rates of cognitive impairment, data on mental capacity assessment in real-world hospital cohorts are required to inform the need for staff training and workforce planning. OBJECTIVES: In unselected medical inpatients, we determined the rate and outcome of mental capacity assessment by decision type and underlying brain/mind disorder, and recorded the discipline of the assessor. METHODS: We included consecutive patients (October-November 2018; November-December 2019) admitted to the complex medicine unit providing acute multidisciplinary care for multi-morbid patients (age ≥ 16 years, average age > 80 years). Audit data were collected at ward multidisciplinary meetings and extracted from electronic patient records. RESULTS: Among 892 patients (mean/SD age = 82.8/8.6, 465 male), 140 (16%) required mental capacity assessment (40/140 (29%) had ≥2 assessments) with 203 assessments in total of which 162 (80%) were done by doctors. Capacity was deemed lacking in 124 (61%) assessments, most commonly in delirium with/without other co-morbid conditions (94/114, 82%) or dementia (9/12, 75%) with lower rates in other disorders (15/27, 56%), and no formal diagnosis of brain/mind disorder (6/50, 12%). Cognitive test scores were overall lower in those lacking capacity (mean/SD abbreviated-mental-test-score = 5.2/2.6, range = 0-10 versus 6.8/2.8, P = 0.001, range = 1-10). Decisions involving discharge planning were most often assessed (48%) followed by treatment (29%), discharge against medical advice (12%) and others (11%). CONCLUSION: Mental capacity assessments were performed frequently and often repeated, justifying the need for robust training in the practical application of the principles of capacity assessment for staff managing complex older patients.

The Oxford digital multiple errands test (OxMET): Validation of a simplified computer tablet based multiple errands test.

Impairments in executive functioning are common following Acquired Brain Injury, though there are few screening tools which present a time efficient and ecologically valid approach to assessing the consequences of executive impairments. We present the Oxford Digital Multiple Errands Test (OxMET), a novel and simplified computer-tablet version of a Multiple Errands Test. We recruited 124 neurologically healthy controls and 105 stroke survivors to complete the OxMET task. Normative data and internal consistency were established from the healthy control data. Convergent and divergent validation was assessed in a mixed subset of 158 participants who completed the OxMET and OCS-Plus. Test-retest reliability was examined across a mixed subset of 39 participants. Finally, we investigated the known-group discriminability of the OxMET. The OxMET demonstrated very high internal consistency, and stable group level test-retest performance as well as good convergent and divergent validity. The OxMET demonstrated high sensitivity and good specificity in overall differentiation of stroke survivors from controls. The Oxford Digital Multiple Errands Test is a brief, easy to administer tool, designed to quickly screen for potential consequences of executive impairments in a virtual environment shopping task on a computer tablet. Initial normative data and validation within a chronic stroke cohort is presented.