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Human Behavior: Biologic and Related Sciences

A 24-year-old man is diagnosed with schizophrenia. He enters a research study looking at dopamine activity in the central nervous system. Which of the following substances will undoubtedly be examined in the young man's cerebrospinal fluid, blood, or urine?

a. Monoamine oxidase

b. Tyrosine

c. Homovanillic acid

d. Tyrosine hydroxylase

e. DOPA (3,4-dihydroxyphenylalanine)

The answer is c. (Kaplan and Sadock, p 40.) Homovanillic acid is the primary metabolite of dopamine. Dopamine activity in the CNS is often assessed in research studies by looking for this metabolite in the cerebrospinal fluid, blood, or urine.

A young man is often the object of his friends' jokes because he drops to the floor whenever he is having a good laugh. From which of the following is this man most likely suffering?

a. Cataplexy

b. Narcolepsy

c. Hysteria

d. Drop seizures

e. Histrionic personality

The answer is a. (Kaplan and Sadock, p 1034.) Cataplexy refers to a sudden loss of muscle tone (ranging in severity from weakness in the knees to a total loss of tone) triggered by strong emotions, which takes place during full wakefulness. Cataplexy is thought to occur because of an abnormal intrusion of REM sleep phenomena in periods of wakefulness. It is usually treated with medications that reduce REM sleep, such as antidepressants. Cataplexy may be a symptom of narcolepsy, characterized by the irresistible urge to fall asleep regardless of the situation.

A 78-year-old man is brought to the physician by his wife because he is becoming increasingly confused. He has been found wandering along the streets unable to find his way home, and has left items in unusual places, like putting his sunglasses in the freezer. On mental status examination the physician would like to test for diffuse cortical degeneration. Which of the following would most likely demonstrate this problem if it is present?

a. Ask the patient about presence of hallucinations.

b. Ask the patient to pick up a piece of paper in his left hand, fold it in half, and place it back on the table.

c. Ask the patient to spell the word ‘WORLD' backward.

d. Ask the patient to copy a figure with multiple intersecting ...

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