Diseases and Disorders of the Nervous System

schizophrenia Characterized by psychotic episodes involving hallucinations & delusions Genetic & environmental components Treatments: focus on drugs that block dopamine receptors, although evidence indicates that the neurotransmitters serotonin, norepinephrine & glutamate are also involved Drugs that reduce symptoms often have negative side effects

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Depressive illness 1.Bipolar disorder swings of mood from high to low 2.Major depression involves persistent low mood  both illnesses have genetic and environmental component  drug treatments against depression often increase the activity of biogenic amines

Alzheimer's disease Dementia characterized by confusion, memory loss, and personality changes Age related, progressive Involves the death of neurons in large areas of the brain Post- mortem diagnosis: neurofibrillary tangles (bundles of degenerated processes) and senile plaques (aggregates of beta amyloid) Membrane secretases cleave a protein into this insoluble peptide that accumulate outside neurons and appear to trigger death of neighboring neurons PIB: chemical that accumulates in regions of amyloid deposits; may help in early detection/ identifying treatments for AD

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Parkinson’s disease Progressive, age related motor disorder characterized by difficulty in movements, rigidity, & muscle tremors Death of neurons in the substantia nigra, which normally release dopamine in the basal nuclei, lead to the motor symptoms of the disease Protein accumulation is associated with neuron degeneration Possibly result of genetic and environmental factors Management of symptoms: drugs such as L-dopa, brain surgery, deep brain stimulation Potential cure: implanting dopamine-secreting neurons in the substantia nigra or basal ganglia

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Epilepsy Chronic condition characterized by abnormal & excessive discharge of neurons resulting in a clinical event (seizure) Affects approx. 2-3% of population Incidence greatest in children and elderly Classifications (based on clinical presentations & electroencephalographic (EEG) findings): 1. Generalized seizures: abnormal EEG originating from both brain hemispheres 2. Partial seizures: abnormal EEG originating from one brain hemisphere (most cases have no know etiology)

Epilepsy (cont.) Treatments (depending on type) 1.Surgery- removal of the focus: (ex. Temporal lobectomy) 2.Corpus Callosotomy (to prevent the spread between hemispheres) 3.Vagus nerve stimulation (device implanted into subcutaneous tissue; attaches to vagus nerve, impulses may be increased with the use of a magnet) 4.Medication

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Cerebrovascular disease 3 rd leading cause of death after heart disease & malignancy; estimated that average of 500,000 new strokes per year will occur in the U.S. Most disabling of neurologic diseases- approx. 50% of survivors have residual neurological deficit & > 25% require chronic care Includes all disorders in which an area of the brain is transiently or permanently affected by ischemia or bleeding and one or more of the cerebral blood vessels are involved in the pathological process Ischemic stroke: accounts for 85% of strokes Hemorrhagic stroke: accounts for 15% of strokes Some causes of ischemic stroke: atherosclerosis, artery disease, drug abuse, migraine, arthritis

Cerebrovascular disease (cont.) TIA (transient ischemic attack): temporary reduction in perfusion to a focal region of the brain. Patient experiences focal neurological deficits such as slurred speech, aphasia, monocular blindness, weakness or paralysis of limb. Duration: 2-15 minutes. May be the only warning of impending stroke

Cerebrovascular disease (cont.) Some risk factors (ischemic stroke): Non modifiable 1.Age: stroke rate doubles each decade after age 55 2.Heart disease: CHF, CAD, AF 3.Male gender, African American or Hispanic race, family history of stroke 4.Prior stroke or TIA; migraine Modifiable Hypertension, hyperlipidemia, alcohol abuse, cigarette smoking, oral contraceptive use, diabetes

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