Cognitive impairment in the context of "Learning disability"

Parkinson's disease (PD), or simply Parkinson's, is a neurodegenerative disease primarily of the central nervous system, affecting both motor and non-motor systems. The motor symptoms are collectively called parkinsonism and include tremors, bradykinesia (slowness in initiating movement), rigidity, and postural instability (difficulty maintaining balance). Non-motor symptoms such as dysautonomia (autonomic nervous system failures), sleep abnormalities, anosmia (decreased ability to smell), and behavioral changes or neuropsychiatric problems, such as cognitive impairment, psychosis, and anxiety, may appear at any stage of the disease. Symptoms typically develop gradually and non-motor issues become more prevalent as the disease progresses.

Most Parkinson's disease cases are idiopathic, though contributing factors have been identified. Pathophysiology involves progressive degeneration of nerve cells in the substantia nigra, a midbrain region that provides dopamine to the basal ganglia, a system involved in voluntary motor control. The cause of this cell death is poorly understood, but involves the aggregation of alpha-synuclein into Lewy bodies within neurons. Other potential factors involve genetic and environmental influences, medications, lifestyle, and prior health conditions.

Neurocysticercosis (NCC) is a parasitic infection of the nervous system caused by the larvae of the tapeworm Taenia solium, also known as the "pork tapeworm". The disease is primarily transmitted through direct contact with human feces, often through the consumption of food or water containing Taenia solium eggs. These eggs hatch in the small intestine and penetrate the intestinal wall. The larvae can travel to the brain, muscles, eyes, and skin. Neurocysticercosis, caused by Taenia solium larvae, differs from taeniasis, which results from adult tapeworm infection.

Neurocysticercosis manifests with various signs and symptoms, influenced by the location, number of lesions, and immune response. While some people may have no symptoms, others may experience seizures, increased pressure in the skull, cognitive impairment, or specific neurological problems. In severe cases, the condition can be life-threatening.

Muscimol, also known as agarin, pantherine, or pyroibotenic acid, is a GABA_A receptor agonist with sedative and hallucinogenic effects and the principal psychoactive constituent of Amanita mushrooms such as Amanita muscaria (fly agaric) and Amanita pantherina (panther cap). It is a 3-hydroxyisoxazole alkaloid and is closely related structurally to the neurotransmitter γ-aminobutyric acid (GABA). The compound is widely used as a ligand and agonist of the GABA_A receptor in scientific research. Muscimol is typically taken orally, but may also be smoked. Peak effects occur after 1 to 3 hours orally and its duration is 4 to 8 hours but up to 24 hours.

The effects of muscimol in humans include central depression, sedation, sleep, cognitive and motor impairment, hallucinations, perceptual distortion, and muscle twitching, among others. Muscimol acts as a potent GABA_A receptor full agonist. It is also a potent GABA_A-ρ receptor partial agonist and a weak GABA reuptake inhibitor. The drug is inactive at the GABA_B receptor but is a substrate of GABA transaminase (GABA-T). Muscimol mostly exerts its effects via GABA_A receptor activation. It is very different from drugs like benzodiazepines and barbiturates as it is an orthosteric agonist of the GABA_A receptor rather than an allosteric modulator. Unlike GABA, muscimol crosses the blood–brain barrier and hence is centrally active. Muscimol, which is also known chemically as 5-aminomethylisoxazol-3-ol, is a conformationally restrained analogue of GABA. The related compound and Amanita spp. constituent ibotenic acid is a prodrug of muscimol.

Cryptococcosis is a potentially fatal fungal infection of mainly the lungs, presenting as a pneumonia, and in the brain, where it appears as a meningitis. Coughing, difficulty breathing, chest pain and fever are seen when the lungs are infected. When the brain is infected, symptoms include headache, fever, neck pain, nausea and vomiting, light sensitivity and confusion or changes in behavior. It can also affect other parts of the body including skin, where it may appear as several fluid-filled nodules with dead tissue.

It is caused by the fungi Cryptococcus neoformans or less commonly Cryptococcus gattii, and is acquired by breathing in the spores from the air. These fungi are found globally in soil, decaying wood, pigeon droppings, and in the hollows of some species of trees. Whereas C. neoformans generally infects people with HIV/AIDS and those on immunosuppressant drugs and does not usually affect fit and healthy people, C. gattii (found in some parts of Canada and the US) does. Once breathed in, the dried yeast cells colonize the lungs, where they are either cleared by immune cells, lie dormant, or cause infection and spread.

Group B streptococcal infection, also known as Group B streptococcal disease or just Group B strep infection, is the infectious disease caused by the bacterium Streptococcus agalactiae. Streptococcus agalactiae is the most common human pathogen belonging to group B of the Lancefield classification of streptococci—hence the name of group B streptococcal (GBS). Infection with GBS can cause serious illness and sometimes death, especially in newborns, the elderly, and people with compromised immune systems.The most severe form of group B streptococcal disease is neonatal meningitis in infants, which is frequently lethal and can cause permanent neuro-cognitive impairment.

S. agalactiae was recognized as a pathogen in cattle by Edmond Nocard and Mollereau in the late 1880s. It can cause bovine mastitis (inflammation of the udder) in dairy cows. The species name "agalactiae" meaning "no milk", alludes to this. Its significance as a human pathogen was first described in 1938, and in the early 1960s, GBS came to be recognized as a major cause of infections in newborns. In most people, Streptococcus agalactiae is a harmless commensal bacterium that is part of the normal human microbiota colonizing the gastrointestinal and genitourinary tracts. Up to 30% of healthy human adults are asymptomatic carriers of GBS.