Alzheimer's Disease (AD) is the most prevalent neurodegenerative disease worldwide and the leading cause of dementia, accounting for 60-80% of dementia cases. The disease is characterized by two pathological hallmarks: extracellular amyloid-beta (Aβ) plaques and intracellular neurofibrillary tangles composed of hyperphosphorylated tau protein. These pathological changes lead to progressive neuronal loss, synaptic dysfunction, and brain atrophy, particularly affecting the hippocampus and cortical regions.
Parkinson's Disease (PD) is the second most common neurodegenerative disorder, affecting approximately 1-2% of individuals over 65 years of age. The disease results from progressive degeneration of dopaminergic neurons in the substantia nigra pars compacta, leading to dopamine depletion in the striatum. Pathologically, PD is characterized by the accumulation of misfolded alpha-synuclein protein forming Lewy bodies and Lewy neurites within affected neurons.
Multiple Sclerosis (MS) is a chronic autoimmune inflammatory disease of the central nervous system characterized by demyelination, axonal damage, and progressive neurological disability. The disease typically affects young adults between 20-40 years of age, with women affected 2-3 times more frequently than men. MS pathology involves immune-mediated destruction of myelin sheaths surrounding axons, leading to disrupted nerve signal transmission and eventual axonal degeneration.
Migraine is a common, disabling neurological disorder affecting approximately 14-15% of the global population, with women three times more affected than men. Migraine is characterized by recurrent episodes of moderate-to-severe headache, typically unilateral and pulsating, accompanied by nausea, vomiting, photophobia, and phonophobia. Approximately 25-30% of migraineurs experience aura—transient neurological symptoms including visual disturbances, sensory changes, or speech difficulties preceding headache onset.
Epilepsy is one of the most common chronic neurological disorders, affecting approximately 0.5-1% of the population worldwide, with over 50 million people living with the condition. Epilepsy is defined by an enduring predisposition to generate epileptic seizures resulting from abnormal excessive or synchronous neuronal activity in the brain. The condition encompasses diverse seizure types (focal, generalized) and epilepsy syndromes with varying etiologies including genetic, structural, metabolic, immune, and infectious causes.
Sleep disorders encompass a wide spectrum of conditions affecting sleep quality, timing, and duration, with significant impacts on daytime functioning, cognitive performance, metabolic health, and quality of life. Major categories include insomnia (difficulty initiating or maintaining sleep), sleep-related breathing disorders (obstructive sleep apnea, central sleep apnea), central disorders of hypersomnolence (narcolepsy, idiopathic hypersomnia), circadian rhythm sleep-wake disorders, parasomnias, and sleep-related movement disorders (restless legs syndrome, periodic limb movement disorder).
Stroke is a leading cause of death and long-term disability worldwide, occurring when blood supply to part of the brain is interrupted (ischemic stroke, 87% of cases) or when a blood vessel ruptures (hemorrhagic stroke, 13% of cases). Ischemic stroke results from thrombotic or embolic occlusion of cerebral arteries, leading to oxygen and glucose deprivation, neuronal injury, and infarction. Risk factors include hypertension, atrial fibrillation, diabetes, dyslipidemia, smoking, and prior cardiovascular disease.