Volume 28, Issue 8

Since Alzheimer’s disease was first described in 1907, many attempts have been made to reveal its main cause. Nowadays, two forms of the disease are known, and while the hereditary form of the disease is clearly caused by mutations in one of several genes, the etiology of the sporadic form remains a mystery. Both forms share similar sets of neuropathological and molecular manifestations, including extracellular deposition of amyloid-beta, intracellular accumulation of hyperphosphorylated tau protein, disturbances in both the structure and functions of mitochondria, oxidative stress, metal ion metabolism disorders, impairment of N-methyl-D-aspartate receptor-related signaling pathways, abnormalities of lipid metabolism, and aberrant cell cycle reentry in some neurons. Such a diversity of symptoms led to proposition of various hypotheses for explaining the development of Alzheimer’s disease, the amyloid hypothesis, which postulates the key role of amyloid-beta in Alzheimer’s disease development, being the most prominent. However, this hypothesis does not fully explain all of the molecular abnormalities and is therefore heavily criticized. In this review, we propose a hypothetical model of Alzheimer’s disease progression, assuming a key role of age-related mitochondrial dysfunction, as was postulated in the mitochondrial cascade hypothesis. Our model explains the connections between all the symptoms of Alzheimer’s disease, with particular attention to autophagy, metal metabolism disorders, and aberrant cell cycle re-entry in neurons. Progression of the Alzheimer’s disease appears to be a complex process involving aging and too many protective mechanisms affecting one another, thereby leading to even greater deleterious effects.

Multiple sclerosis (MS) is a chronic, progressive disease of the central nervous system that is characterised by inflammatory damage to the myelin sheath. Though often neglected, cognitive impairment is a common feature of MS that affects 43–70% of patients. It has a sophisticated neuroanatomic and pathophysiologic background and disturbs such vital cognitive domains as speed of information processing, memory, attention, executive functions and visual perceptual functions. In recent years there has been growing interest in neuroimaging findings with regard to cognitive impairment in MS. The possible options of managing cognitive dysfunction in MS are pharmacologic interventions, cognitive rehabilitation and exercise training; however, not enough evidence has been presented in this field. The aim of our article is to provide current knowledge on cognitive impairment in MS based on the most recent scientific results and conclusions with regard to affected cognitive domains, neuropsychological assessment, underlying mechanisms of this disturbance, neuroimaging findings and therapeutic options.

Alzheimer’s disease (AD) is the most common neurodegenerative disorder leading to dementia in the elderly population. AD is associated with the buildup of β-amyloid and tau, which aggregate into extracellular plaques and neurofibrillary tangles. Although the exact mechanism of pathological process of AD is unclear, the dysfunction of protein degradation mechanisms has been proposed to play an important role in AD. The cellular degradation of abnormal or misfolded proteins consists of three different mechanisms: the ubiquitin proteasomal system (UPS), autophagy-lysosomal pathway (ALP), and interaction of molecular chaperones with UPS or ALP. Any disturbance to these systems causes proteins to accumulate, resulting in pathological process of AD. In this review, we summarize the knowledge of protein degradation pathways in the pathogenesis of AD in light of the current literature. In the future, the regulation UPS or ALP machineries could be the cornerstones of the treatment of AD.

Mutant mice deficient in hyaluronan (HA) have an epileptic phenotype. HA is one of the major constituents of the brain extracellular matrix. HA has a remarkable hydration capacity, and a lack of HA causes reduced extracellular space (ECS) volume in the brain. Reducing ECS volume can initiate or exacerbate epileptiform activity in many in vitro models of epilepsy. There is both in vitro and in vivo evidence of a positive feedback loop between reduced ECS volume and synchronous neuronal activity. Reduced ECS volume promotes epileptiform activity primarily via enhanced ephaptic interactions and increased extracellular potassium concentration; however, the epileptiform activity in many models, including the brain slices from HA synthase-3 knockout mice, may still require glutamate-mediated synaptic activity. In brain slice epilepsy models, hyperosmotic solution can effectively shrink cells and thus increase ECS volume and block epileptiform activity. However, in vivo , the intravenous administration of hyperosmotic solution shrinks both brain cells and brain ECS volume. Instead, manipulations that increase the synthesis of high-molecular-weight HA or decrease its breakdown may be used in the future to increase brain ECS volume and prevent seizures in patients with epilepsy. The prevention of epileptogenesis is also a future target of HA manipulation. Head trauma, ischemic stroke, and other brain insults that initiate epileptogenesis are known to be associated with an early decrease in high-molecular-weight HA, and preventing that decrease in HA may prevent the epileptogenesis.

Brain iron deposits have been reported consistently in imaging and histologic examinations of patients with neurodegenerative disorders. While the origins of this finding have not been clarified yet, it is speculated that impaired iron homeostasis or deficient transport mechanisms result in the accumulation of this highly toxic metal ultimately leading to formation of reactive oxygen species and cell death. On the other hand, there are also those who support that iron is just an incidental finding, a by product of neuronal loss. A literature review has been performed in order to present the key findings in support of the iron hypothesis of neurodegeneration, as well as to identify conditions causing or resulting from iron overload and compare and contrast their features with the most prominent neurodegenerative disorders. There is an abundance of experimental and observational findings in support of the hypothesis in question; however, as neurodegeneration is a rare incident of commonly encountered iron-associated disorders of the nervous system, and this metal is found in non-neurodegenerative disorders as well, it is possible that iron is the result or even an incidental finding in neurodegeneration. Understanding the underlying processes of iron metabolism in the brain and particularly its release during cell damage is expected to provide a deeper understanding of the origins of neurodegeneration in the years to come.

Studies have shown that patients who practice functional movements at home in conjunction with outpatient therapy show higher improvement in motor recovery. However, patients are not qualified to monitor or assess their own condition that must be reported back to the clinician. Therefore, there is a need to transmit physiological data to clinicians from patients in their home environment. This paper presents a review of wearable technology for in-home health monitoring, assessment, and rehabilitation of patients with brain and spinal cord injuries.