Neuroinflammatory responses in Alzheimer's disease.

Neuroinflammatory responses in Alzheimer's disease (AD) are complex and not fully understood. They involve various cellular and molecular players and associate interaction between the central nervous system (CNS) and the periphery. Amyloid peptides within the senile plaques and abnormally phosphorylated tau in neurofibrillary tangles are able to initiate inflammatory responses, in brain of AD patients and in mouse models of this disease. The outcome of these responses on the pathophysiology of AD depends on several factors and can be either beneficial or detrimental. Thus, understanding the role of neuroinflammation in AD could help to develop safer and more efficient therapeutic strategies. This review discusses recent knowledge on microglia responses toward amyloid and tau pathology in AD, focusing on the role of Toll-like receptors and NOD-like receptor protein 3 (NLRP3) inflammasome activation in microglial cells.

The Contribution of the Locus Coeruleus-Noradrenaline System Degeneration during the Progression of Alzheimer's Disease.

Alzheimer's disease (AD), which is characterized by extracellular accumulation of amyloid-beta peptide and intracellular aggregation of hyperphosphorylated tau, is the most common form of dementia. Memory loss, cognitive decline and disorientation are the ultimate consequences of neuronal death, synapse loss and neuroinflammation in AD. In general, there are many brain regions affected but neuronal loss in the locus coeruleus (LC) is one of the earliest indicators of neurodegeneration in AD. Since the LC is the main source of noradrenaline (NA) in the brain, degeneration of the LC in AD leads to decreased NA levels, causing increased neuroinflammation, enhanced amyloid and tau burden, decreased phagocytosis and impairment in cognition and long-term synaptic plasticity. In this review, we summarized current findings on the locus coeruleus-noradrenaline system and consequences of its dysfunction which is now recognized as an important contributor to AD progression.

CNS Superficial Siderosis Mimicking a Motor Neuron Disease.

Superficial siderosis of the central nervous system (SS-CNS) is a rare condition characterized by a hemosiderin accumulation along the subpial surfaces and arises from an intermittent chronic bleeding in the subarachnoid space usually as a result of a chronic subarachnoid hemorrhage by trauma, vascular malformations, CNS tumors, or cerebral amyloid angiopathy (CAA). We present a 61-year-old male with a 12-year history of limb weakness, muscle wasting, cramps, clumsiness, progressive unsteady gait, and fine motor impairments. His medical history included the resection of a left parietal meningioma and a myxopapillary ependymoma near the conus terminalis (L3/4) at the age of 51 years. The clinical examination revealed a motor neuron syndrome with a clear bilateral wasting of the hand muscles, a diffuse atrophy of the shoulder and calf muscles, and a weakness of the arms, fingers, hips, and feet. Deep tendon reflexes were symmetrically briskly hyperactive. Standing and walking were only possible with a support. Magnetic resonance imaging of the entire neuroaxis showed progressive severe cerebral, brainstem, and spinal superficial siderosis in form of extensive hypointensities on T2-weighted gradient-echo images and susceptibility-weighted sequences. Despite a successful neurosurgical removal of the tumors and delaed medical treatment with an iron chelator for one year, we observed no clinical recovery or stability in our patient, making this case unique, and suggesting an irreversible neurodegenerative process. This case reinforces the need of including SS-CNS in the list of amyotrophic lateral sclerosis (ALS)-mimics and demonstrates the fundamental use of a complete neuraxial MRI investigation on evaluating possible ALS cases.

Screening for Niemann-Pick Type C Disease in a Memory Clinic Cohort.

Niemann-Pick type C disease (NPC) is a neurovisceral lysosomal storage disorder with a heterogeneous phenotype including ataxia, cognitive impairment, impairment of vertical saccades, and psychiatric symptoms, among many others. Based on clinical, genetic, and biomarker findings, recent guidelines put forward a screening for atypical and oligosymptomatic forms of NPC in clinical niches with an increased risk. Here, we report methods and results of a negative screening study in the niche of a memory clinic. We retrospectively and prospectively identified 83 patients with unclassified cognitive impairment (15 dementia, 46 mild cognitive impairment, and 22 progressive subjective cognitive decline) before 60 years of age (82 patients between 41 and 60 years). We explored the prevalence of clinical features compatible with NPC and measured plasma levels of chitotriosidase and cholestantriol. The NPC suspicion index indicated high probability for NPC in 3 and moderate probability in 16 patients. Prevalent (>5%) neurological and psychiatric features were depression, seizures, ataxia, dysarthria, and psychotic symptoms. Vertical gaze palsy without parkinsonism was observed in one patient. Cholestantriol levels were only abnormal in one patient. Chitotriosidase levels were susceptible to slight elevations that were reproducible in only two of five patients. Our study does not exclude NPC among memory clinic patients. Instead, we suggest conducting prospective screening studies in younger cohorts that include a focused neurological examination. Excluding minor cognitive impairment and discarding depression as an independent disease symptom probably further improve screening effectivity but may delay or miss therapeutic options in early or mild disease.