What is the estimated risk of developing schizophrenia throughout the lifetime of an average person in the population?
A. It was widely believed that schizophrenia is a universal illness with a more or less equivalent global prevalence of 1%. McGrath and colleagues have recently challenged this figure. Compiling data from nearly 200 studies that reported on epidemiology of schizophrenia, they estimated the mean lifetime prevalence of schizophrenia (the proportion of individuals in the population who have ever manifested the illness and who are alive on a given day) as 4 per 1000. Note that DSM-IV states that the lifetime prevalence of schizophrenia is often reported to be 5 to15 per 1000. McGrath and colleagues also determined that the point prevalence of schizophrenia (the proportion of individuals who manifest the illness at a given point of time) is 4.6 per 1000. The lifetime morbid risk of schizophrenia (the probability of a person developing the illness during his or her lifetime) is determined to be at a rate of 7 per 1000 (nearly 1 in 150 as mentioned in the question).
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Which of the following is NOT true with respect to narcolepsy?
B. Narcolepsy is characterized by irresistible attacks of sleep together with cataplexy (brief episodes of sudden bilateral loss of muscle tone, often in association with intense emotion) and recurrent hypnapompic or hypnagogic hallucinations or sleep paralysis at the beginning or end of a sleep episode. Characteristically, the EEG shows REM pattern during hypnagogic or hypnapompic hallucinations and sleep paralysis. The narcoleptic sleep is usually a refreshing (REM) sleep. Sleep onset REM is characteristic. Strong genetic association with HLA-DR2 locus is noted, with an autosomal dominant inheritance. HLA-DR2 is found in 90 to 100% of patients with narcolepsy. It is also shown that patients with narcolepsy are deficient in the neurotransmitter hypocretin (also called orexin) associated with hypothalamic modulation of appetite and alertness. EEG is normal between narcoleptic attacks.
Somnambulism is a disorder of which stage of sleep?
B. Sleepwalking or somnambulism consists of various complex motor behaviours during the first third of sleep where slow wave NREM (stage III and IV) phase predominates. Usually, the patient will not retain any memory of getting up and walking during sleep. The motor acts are often perseverative in nature; incidence is most common around age 12.
Which of the following is a sleep disturbance characteristic of mania?
C. Both mania and depression are characterized by various neurovegetative signs – disturbances in sleep, appetite, weight, energy levels, and circadian functions. In depression early morning awakening is characteristic. To qualify as early morning awakening, a patient must wake up at least 2 hours prior to his usual waking time. In mania, there is increased energy associated with reduced need for sleep. Patients can go on for many days with barely any sleep. Paradoxically, sleep deprivation itself can induce a state similar to hypomania in some susceptible individuals.
Which of the following is NOT a medical cause of panic attacks?
D. Panic attacks can occur in various medical conditions such as hyperthyroidism, phaeochromocytoma, epilepsy, cardiac arrhythmias, and chronic obstructive pulmonary disease. It is also noted that some medical conditions occur slightly more commonly in those with panic disorder, for example mitral valve prolapse, hyperthyroidism.
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