Intellectual enrichment and genetic modifiers of cognition and brain volume in Huntington's disease

Cognitive engagement may slow clinical progression and brain atrophy in Huntington's disease

Lifelong cognitive engagement conveys benefits in Huntington's disease (HD) and may positively affect non-cognitive domains in other populations. However, the effect of lifelong cognitive engagement on the progression of motor and psychiatric domains in HD remains unknown, as is its neurobiological basis. Forty-five HD individuals completed the Cognitive Reserve Questionnaire (CRQ) and longitudinal clinical evaluation (maximum total of six visits, mean inter-assessment duration of 13.53 ± 4.1 months). Of these, thirty-three underwent longitudinal neuroimaging (18 ± 6 months follow-up). Generalized linear mixed-effects models were executed to predict the effect of individual differences in lifelong cognitive engagement on HD clinical progression and voxel-based morphometry to explore the impact of lifelong cognitive engagement on whole-brain gray matter volume atrophy. Controlling for age, disease stage, and sex, higher CRQ scores were associated with reduced overall severity and longitudinal progression across cognitive, motor, and psychiatric domains. Those with higher CRQ scores demonstrated reduced gray matter volume loss in the middle frontal gyrus, supplementary motor area, and middle cingulate. This putative impact on HD clinical progression may be conferred by preservation of brain volume in neural hubs that integrate executive function with action initiation and behavioral regulation, providing support for early cognitive engagement, even prior to diagnosis.

Circadian Interventions in Preclinical Models of Huntington's Disease: A Narrative Review

Huntington's Disease (HD) is a neurodegenerative disorder caused by an autosomal-dominant mutation in the huntingtin gene, which manifests with a triad of motor, cognitive and psychiatric declines. Individuals with HD often present with disturbed sleep/wake cycles, but it is still debated whether altered circadian rhythms are intrinsic to its aetiopathology or a consequence. Conversely, it is well established that sleep/wake disturbances, perhaps acting in concert with other pathophysiological mechanisms, worsen the impact of the disease on cognitive and motor functions and are a burden to the patients and their caretakers. Currently, there is no cure to stop the progression of HD, however, preclinical research is providing cementing evidence that restoring the fluctuation of the circadian rhythms can assist in delaying the onset and slowing progression of HD. Here we highlight the application of circadian-based interventions in preclinical models and provide insights into their potential translation in clinical practice. Interventions aimed at improving sleep/wake cycles' synchronization have shown to improve motor and cognitive deficits in HD models. Therefore, a strong support for their suitability to ameliorate HD symptoms in humans emerges from the literature, albeit with gaps in our knowledge on the underlying mechanisms and possible risks associated with their implementation.

Mild cognitive impairment in Huntington's disease: challenges and outlooks

Although Huntington's disease (HD) has classically been viewed as an autosomal-dominant inherited neurodegenerative motor disorder, cognitive and/or behavioral changes are predominant and often an early manifestation of disease. About 40% of individuals in the presymptomatic period of HD meet the criteria for mild cognitive impairment, later progressing to dementia. The heterogenous spectrum of cognitive decline is characterized by deficits across multiple domains, particularly executive dysfunctions, but the underlying pathogenic mechanisms are still poorly understood. Investigating the pathophysiology of cognitive changes may give insight into important and early neurodegenerative events. Multimodal imaging revealed circuit-wide gray and white matter degenerative processes in several key brain regions, affecting prefronto-striatal/cortico-basal ganglia circuits and many other functional brain networks. Studies in transgenic animal models indicated early synaptic dysfunction, deficient neurotrophic transport and other molecular changes contributing to neuronal death. Synaptopathy within the cerebral cortex, striatum and hippocampus may be particularly important in mediating cognitive and neuropsychiatric manifestations of HD, although many other neuronal systems are involved. The interaction of mutant huntingtin protein (mHTT) with tau and its implication for cognitive impairment in HD is a matter of discussion. Further neuroimaging and neuropathological studies are warranted to better elucidate early pathophysiological mechanisms and to develop validated biomarkers to detect patients' cognitive status during the early stages of the condition significantly to implement effective preventing or management strategies.

Celebrating the life and research of BNA Past-President Colin Blakemore

Professor Sir Colin Blakemore was a remarkable neuroscientist, persuasive communicator, and brave advocate for animal research who, sadly, passed away in June 2022 from amyotrophic lateral sclerosis. His work helped establish the concept of neuronal plasticity, which was fundamental to our understanding of the postnatal brain and continues to impact our outlook on neurodegenerative disorders. The BNA2023 Festival of Neuroscience dedicated its last plenary session in his honour, bringing together five prominent neuroscientists whose careers were shaped by Professor Blakemore. Here, we summarise the speakers' reflections on how Colin's support, generosity, and foresight influenced their academic paths, inspired their research, and changed their outlook on life.

Use it or lose it: gene-environment interactions at the nexus of expanding genes and shrinking brains in Huntington's disease and other experience-dependent disorders of ageing

This scientific commentary refers to 'Intellectual enrichment and genetic modifiers of cognition and brain volume in Huntington's disease' by Papoutsi et al. (https://doi.org/10.1093/braincomms/fcac279).