Biology 3201 Nervous System # 7: Nervous System Disorders Alzheimer's Disease first identified by German physician, Alois Alzheimer, in 1906 most common neurodegenerative disease two thirds of cases of dementia progressive impairment in memory, judgment, decision making, orientation to physical surroundings, and language 1
Alzheimer's Disease A degenerative disorder that affects the brain and causes dementia, which is an impairment of the brain s intellectual function such as memory and orientation, especially late in life It results from deposits of a protein called amyloid which disrupts communication between nerve cells. As well, acetylcholine levels drop People may also suffer personality changes No cure, and limited treatments Alzheimer's Disease Diagnosis is based on neurologic examination and the exclusion of other causes of dementia; a definitive diagnosis can be made only at autopsy. 2
Multiple Sclerosis A serious progressive disease of the central nervous system. The myelin sheath surrounding the nerve cells becomes inflamed or damaged. This disrupts the nerve impulses that are normally produced. Believed to be an autoimmune disorder, where the body s own immune cells attack myelin No cure presently known; treatment includes autoimmune suppressants Various symptoms depending on where disruptions occur such as blurred or double vision, slurred speech, loss of coordination, weaknesses, and possibly seizures 3
Huntington s Disease George Huntington (1872) Huntington s chorea (greek for dance ) about 1 in every 10,000 Huntington s Disease a lethal disorder in which the brain progressively deteriorates over a period of 15 years; symptoms typically appear after age 35 Causes progressive decrease in mental and emotional abilities and loss of control of major muscle movements Autosomal dominant no cure Symptoms include memory loss, dementia, involuntary twitching, chorea (jerky movements) and personality changes 4
Huntington s Disease Specifically affected are cells of the basal ganglia, structures deep within the brain that have many important functions, including coordinating movement. Parkinson s disease A chronic movement disorder caused by gradual decline of the neurons that produce dopamine Symptoms begin as slight tremors and stiffness of limbs on one side of the body. Over time, the tremors spread to both sides of the body and movements become slow. No cure, but symptoms can be treated with drugs or surgery (if necessary) 5
Symptoms of Parkinson s disease lack of coordination Tremors stiff muscles and joints difficulty moving Treatment for Parkinson s Medications to increase dopamine levels 6
Amyotrophic Lateral Sclerosis Amyotrophic Lateral Sclerosis (ALS) rapidly progressive attacks the nerve cells responsible for controlling voluntary muscles When these muscles fail to receive messages, they lose strength, atrophy and die 7
ALS ALS does not impair a person's mind, personality, intelligence, or memory, nor does it affect a person's ability to see, smell, taste, hear, or recognize touch. Meningitis A bacterial or viral infection of the meninges, the three membranes that cover and protect the brain and spinal cord Viral meningitis is more common, but bacterial meningitis is fatal (10% fatality, and survivors often suffer from complications like hearing impairment) Symptoms include headache, fever, stiff neck, light sensitivity, vomiting, and drowsiness Testing of meninges is done via a spinal tap There are vaccines available for some bacterial meningitis, but none for viral meningitis 8
Muscular Dystrophy many forms genetic diseases progressive weakness and degeneration of the skeletal muscles that control movement Duchenne MD primarily affects boys and is the result of mutations in the gene that regulates dystrophin - a protein involved in maintaining the integrity of muscle fiber. Inheritance X-linked recessive. DMD primarily affects boys, who inherit the disease through their mothers. Women can be carriers of DMD but usually exhibit no symptoms 9
Diagnosing Nervous System Disorders 1. MRI stands for magnetic resonance imaging uses a combination of large magnets, radio frequencies, and computers to produce detailed images of the brain and other structures in the body Diagnosing Nervous System Disorders 2. EEG stands for electroencephalogram Electrodes are attached to the forehead and scalp and brain waves are recorded Printout of brain waves help diagnose certain disorders like sleep disorders and locating tumors 3. CAT Scan stands for computerized axial tomography scan takes a series of the cross-sectional X-rays to create a computer generated three dimensional image of a part of the body 10
Drugs and Homeostasis 3201 STS Module 1 Mental Illness mental illness is a result of imbalances of neurotransmitters. once erroneously considered to have no biological basis At one time, sufferers of mental illness were deemed as weak-minded and lacking the skills to cope with life. 11
Clinical Depression I most frequently encountered mental illness. may afflict up to 5% of the population Clinical Depression II Symptoms distinct change in mood accompanied by an extreme feeling of hopelessness. loss of appetite, weight loss, headaches, sleeplessness, loss of energy, tiredness, and anxiety. 12
Clinical Depression III Biological Basis Serotonin, dopamine, and or noradrenaline levels are not normal either secrete too little or too much of the neurotransmitter which is broken down by enzymes (monoamine oxidases) when it is reabsorbed into nerve endings. Clinical Depression IV Three major classes of drugs: 1. monoamine oxidase inhibitors (MAOI s) 2. selective serotonin reuptake inhibitors (SSRI s) 3. tricyclic compounds. 13
Clinical Depression V MAOI s believed to inhibit monoamine oxidase (MAO). MAO is an enzyme that is believed to break down serotonin and noradrenaline. Clinical Depression VI Serotonin re-uptake inhibitors (SSRI s) are the most widely prescribed antidepressant. A well known example is Prozac. functions by blocking serotonin uptake and therefore increase the levels of serotonin at the synapse. 14
Clinical Depression VII Tricyclic inhibitors appear to slow the re-uptake of serotonin and noradrenaline. Bipolar Disorder I also known as manic depression. severe mood swings ranging from mania to depression, with normal periods in between. 15
Bipolar Disorder II Treatment medication and psychotherapy. The most common medication is lithium carbonate. It functions by maintaining the chemical balances in the brain to prevent mood swings. Symptoms: Schizophrenia I disturbance of thought patterns hallucinations, delusions and paranoia. Thesesymptoms all represent a loss of contact with reality. 16
Schizophrenia II biological basis: form of dopamine dysfunction, such as excessive dopamine activity, is believed to cause schizophrenia. Treatment: Schizophrenia III Chlorpromazine and related drugs function in blocking the dopamine receptors. Unfortunately, the side effects are similar to Parkinson s disease. 17