Nigral involvement and nigrostriatal dysfunction in Huntington's disease: Evidences from an MRI and SPECT study

Risk Factors and Interventions for Suicide in Huntington's Disease-A Systematic Review

Background/Objectives: Huntington's disease (HD) is an autosomal dominant genetic disorder causing progressive neurodegeneration which, aside from symptomatic therapies for controlling psychological and motor problems, currently has no effective treatment. People who receive this diagnosis often feel disoriented and lost without guidance. Furthermore, HD patients are estimated to have a two to seven times greater risk of suicide death compared to the general population. The current review investigates the complex relationship between HD and suicide, seeking to identify key risk factors influencing suicidal ideation and behaviour in affected individuals. Methods: We conducted a systematic review following the PRISMA guidelines. Studies were searched for on the PubMed, Cochrane, and Web of Science databases, and 17 articles met the inclusion criteria. Results: The findings reveal that emotional strain, neuropsychiatric symptoms, and the absence of a cure contribute to heightened suicidal tendencies in HD patients. Critical periods for suicide risk coincide with early symptomatic stages of disease or the successive phase, with the loss of independence impacting on daily functioning. Risk factors associated with HD include a depressive mood, cognitive impairments, and a history of suicide attempts. Conclusions: From a prevention perspective, a comprehensive multidisciplinary and multidimensional approach could enhance the overall well-being of people with HD. In particular, screening for suicidal thoughts in people with HD could mitigate suicide risk.

Dual phase 18F-FP CIT PET and 99mTc- ECD SPECT findings of Huntington's disease

Fluorine-18 N-3-fluoropropyl-2-beta-carboxymethoxy-3-beta-(4-iodophenyl) nortropane (18F- FP CIT) has been used for the differential diagnosis of atypical parkinsonian disorders, and Technetium 99m ethyl cysteinate dimer (99mTc- ECD) has been used for evaluation of cerebral blood flow. A 60-year-old female with a history of Huntington's disease (HD) with full mutation of cytosine-adenine-guanine (GAG) 18/43 repeats underwent early and late 18F- FP CIT positron emission tomography/computed tomography (PET/CT) and 99mTc- ECD single-photon emission computed tomography (SPECT). The 18F-FP CIT PET/CT showed decreased uptake in both basal ganglia, both frontal and parietotemporal lobes at early images, and decreased presynaptic dopamine transporter (DAT) binding in both ventral & posterior putamen at late images. 99mTc- ECD SPECT showed decreased perfusion in both basal ganglia, both frontal and temporal lobes. Early 18F- FP CIT PET/CT and 99mTc- ECD SPECT images showed similar findings in Huntington's disease.

Neuromelanin Magnetic Resonance Imaging of the Substantia Nigra in Huntington's Disease

BACKGROUND

Huntington's disease (HD) is an autosomal-dominant neurodegenerative disorder inducing motor, psychiatric changes and cognitive decline, characterized pathologically by striatal atrophy. Pathological changes in the extra-striatal structures, such as the substantia nigra (SN), and abnormalities in pre-synaptic striatal dopamine neurotransmission are also known to occur. Neuromelanin (NM)-sensitive magnetic resonance imaging (NM-MRI) is an innovative technique that was recently developed allowing the in vivo study of pathological changes in the dopaminergic neurons of the SN.

OBJECTIVE

To investigate the SN MR signal in HD patients.

METHODS

We performed a cross-sectional study using a specific T1-weighted MR sequence to visualize NM. The areas and signal intensity contrast ratios of the T1 hyperintense SN regions were obtained using a semi-automatic segmentation method.

RESULTS

A total of 8 HD patients and 12 healthy subjects were evaluated. The SN area was markedly reduced in the HD group compared with the control group (p = 0.02), even after normalization of the SN area with the midbrain area and age correction (p = 0.01). There was a significant reduction in the intensity contrast ratio of the hyperintense SN areas to crus cerebri in HD patients comparing with controls (p = 0.04) after correction for age.

CONCLUSIONS

NM-sensitive MR techniques were used for the first time to study the SN in HD patients, showing loss of NM in this region, supporting the implication of dopaminergic neuronal changes in disease pathology. Future research needs to be conducted to evaluate the potential of SN area and intensity contrast as biomarkers for HD.

The Renin-Angiotensin System in Huntington's Disease: Villain or Hero?

Huntington’s Disease (HD) is an autosomal dominant, progressive neurodegenerative disorder characterized by severe symptoms, including motor impairment, cognitive decline, and psychiatric alterations. Several systems, molecules, and mediators have been associated with the pathophysiology of HD. Among these, there is the Renin-Angiotensin System (RAS), a peptide hormone system that has been associated with the pathology of neuropsychiatric and neurodegenerative disorders. Important alterations in this system have been demonstrated in HD. However, the role of RAS components in HD is still unclear and needs further investigation. Nonetheless, modulation of the RAS components may represent a potential therapeutic strategy for the treatment of HD.

Dysregulation of Corticostriatal Connectivity in Huntington's Disease: A Role for Dopamine Modulation

Aberrant communication between striatum, the main information processing unit of the basal ganglia, and cerebral cortex plays a critical role in the emergence of Huntington’s disease (HD), a fatal monogenetic condition that typically strikes in the prime of life. Although both striatum and cortex undergo substantial cell loss over the course of HD, corticostriatal circuits become dysfunctional long before neurons die. Understanding the dysfunction is key to developing effective strategies for treating a progressively worsening triad of motor, cognitive, and psychiatric symptoms. Cortical output neurons drive striatal activity through the release of glutamate, an excitatory amino acid. Striatal outputs, in turn, release γ-amino butyric acid (GABA) and exert inhibitory control over downstream basal ganglia targets. Ample evidence from transgenic rodent models points to dysregulation of corticostriatal glutamate transmission along with corresponding changes in striatal GABA release as underlying factors in the HD behavioral phenotype. Another contributor is dysregulation of dopamine (DA), a modulator of both glutamate and GABA transmission. In fact, pharmacological manipulation of DA is the only currently available treatment for HD symptoms. Here, we review data from animal models and human patients to evaluate the role of DA in HD, including DA interactions with glutamate and GABA within the context of dysfunctional corticostriatal circuitry.

Functional neuroimaging and chorea: a systematic review

Chorea is a hyperkinetic movement disorder consisting of involuntary irregular, flowing movements of the trunk, neck or face. Although Huntington’s disease is the most common cause of chorea in adults, chorea can also result from many other neurodegenerative, metabolic, and autoimmune conditions. While the pathophysiology of these different conditions is quite variable, recent advances in functional imaging have enabled the development of new methods for analysis of brain activity and neuronal dysfunction. In this paper we review the growing body of functional imaging data that has been performed in chorea syndromes and identify particular trends, which can be used to better understand the underlying network changes within the basal ganglia. While it can be challenging to identify whether changes are primary, secondary, or compensatory, identification of these trends can ultimately be useful in diagnostic testing and treatment in many of the conditions that cause chorea.