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Chapter 9

chapter 9

16 Pages
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Department
Psychology
Course Code
PSYC62H3
Professor
Suzanne Erb

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Chapter 9
PSYCHOSTIMULANTS
Psychostimulants, in low to moderate doses, these drugs produce heightened mood
(at its extreme, it is described as euphoria), increase vigilance and alertness, and
reduce fatigue and the tendency to sleep.
These properties also results in enhanced performances on a variety of tasks,
althought the dose response functions are inverted U- or J-shaped.
That is, there are a range of doses in which enhancement occurs, but as the dose
increases beyond this range, performances return to nondrug levels or worsens. (
heart rate and BP)
Other frequently used terms for these drugs are behavioural stimulants and CNS
stimulants; however, these terms do not do justice to the actual common properties of
these drugs.
Some behaviour may increase while others may decrease, depending on the dose and
the frequency of the behaviour typically observed without the drugs and depending
on the person.
The same applies to the neuron activity within the CNS.
None of these terms mentioned adequately describes the effects of these drugs if the
drugs are used in large amounts acutely or moderate amounts chronically.
Within this category are several structurally different types of drugs, most common =
caffeine.
Then you have nicotine, and then you have amphetamines together with other
structurally related drugs, comprise another popular class.
These include methyphenidate (proprietary name, Ritalin) and pemoline (Cylert),
which are structurally and pharmacologically similar to the amphetamines.
Cocaine is perhaps the most notorious of the groups
Caffeine
Caffeine is the most widely used behaviourally active drug in the world
It is one of several substances referred to as methylxanthines.
www.notesolution.com
Typical adult in US consumes about 200-300mg of caffeine a day.
Based on typical pattern of use throughout the day and a plasma half-life of ~ 5
hours, peak caffeine plasma levels typically occur in the early evening.
It is difficult to determine the overall time course and impact of caffeine on an
individual as they differ.
In intravenous drug self-administration experiments with animals, caffeine has been
shown to have reinforcing effects in some cases but not in others.
Most evidence suggests that caffeine is rated as having the most desirable and
pleasant reactions in heavy coffee drinkers, particularly after they have not had any
coffee for several hours and some people show normally show dysphoric effect for
coffee in general.
This finding suggests that many of the reinforcing effects of caffeine stem from its
ability to terminate caffeine withdrawal.
However, research indicates that the average caffeine intake of coffee consumers
does not predict the occurrence of withdrawal
When coffee consumers are tested with caffeinated and decaffeinated coffee, they
were more likely to self-administer caffeinated coffee.
The effects of caffeine vary considerably among individuals in terms of wakefulness,
psychomotor coordination, mood alterations, and autonomic nervous system
response.
Two cups of coffee, which contains ~ 150 mg of caffeine, has the mood-elevating and
fatigue-relieving properties of threshold doses of amphetamine (~ 2 to 5mg)
However, larger doses generally do not have more of a mood-elevating effect, and 7 to
10 cups of coffee may cause insomnia, restlessness, mild sensory disturbances, or
muscle tenseness ( collectively called caffeinism), or may precipitate anxiety or
panic attacks in susceptible individuals
Caffeine typically raises BP slightly in both men and women, but apparently via
different mechanisms.
Heart rate changes are variable and with some caffeine doses, may actually
decrease.
Increases in galvanic skin conductance level and reactivity are generally noted.
www.notesolution.com
Caffeine may not increase all indexes of arousal or change them in the same way in
all persons
Persons who consume low to moderate doses of caffeine (30 to 450mg) typically
display dose-dependent improvements in indices of arousal, daytime alertness,
vigilance, and some aspects of psychomotor performances and cognitive functions,
such as reactions time, sustained attention, and information processing, and they
experience predominantly positive subjective effects on mood, characterized by
increased well-being, energy and concentration.
These beneficial effects are particularly evidenced when the individuals are tested
under conditions of caffeine deprivation or total abstinence in regular caffeine users
or following partial or total sleep deprivation.
As little as 32mg of caffeine has been shown to significantly improve auditory
vigilance and visual reaction time.
Caffeine can produce an increased capacity for both muscular work and sustained
intellectual effort, but it can also disrupt arithmetic skills and task performance
when delicate muscular coordination and accurate timing are required.
The effects of caffeine on endurance (and probably other aspects of performance) are
biphasic; that is, lower doses (3-6 mg/kg) enhances performance and higher doses
produce no benefits or decrease performance.
Several studies on efficiency of information processing in humans have shown that
the effects of caffeine are dependent upon dose, talk demands, the subjects sex, and
the subjects typical level of arousal.
Some studies have concluded that extraoverts (or high impulsives) tend to show dose-
dependent improvements in performance, whereas introverts (or low impulsives)
show improvements with lower doses and decrement with higher doses and other
show no change.
Other than the conclusion that the behavioural effects of caffeine are quite subtle,
there does not appear to be a consensus as to whether caffeine improves information-
processing efficiency in general.
It is common belief caffeine can counteract the effects of sedative-hypnotic type
drugs, but the empirical evidence for this belief is equivocal.
The equivalent of two or three cups of coffee (250mg caffeine) has been shown to
significantly reduce next-day benzodiazepine-induced drowsiness.
www.notesolution.com

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Description
Chapter 9 PSYCHOSTIMULANTS Psychostimulants, in low to moderate doses, these drugs produce heightened mood (at its extreme, it is described as euphoria), increase vigilance and alertness, and reduce fatigue and the tendency to sleep. These properties also results in enhanced performances on a variety of tasks, althought the dose response functions are inverted U- or J-shaped. That is, there are a range of doses in which enhancement occurs, but as the dose increases beyond this range, performances return to nondrug levels or worsens. ( heart rate and BP) Other frequently used terms for these drugs are behavioural stimulants and CNS stimulants; however, these terms do not do justice to the actual common properties of these drugs. Some behaviour may increase while others may decrease, depending on the dose and the frequency of the behaviour typically observed without the drugs and depending on the person. The same applies to the neuron activity within the CNS. None of these terms mentioned adequately describes the effects of these drugs if the drugs are used in large amounts acutely or moderate amounts chronically. Within this category are several structurally different types of drugs, most common = caffeine. Then you have nicotine, and then you have amphetamines together with other structurally related drugs, comprise another popular class. These include methyphenidate (proprietary name, Ritalin) and pemoline (Cylert), which are structurally and pharmacologically similar to the amphetamines. Cocaine is perhaps the most notorious of the groups Caffeine Caffeine is the most widely used behaviourally active drug in the world It is one of several substances referred to as methylxanthines. www.notesolution.com Typical adult in US consumes about 200-300mg of caffeine a day. Based on typical pattern of use throughout the day and a plasma half-life of ~ 5 hours, peak caffeine plasma levels typically occur in the early evening. It is difficult to determine the overall time course and impact of caffeine on an individual as they differ. In intravenous drug self-administration experiments with animals, caffeine has been shown to have reinforcing effects in some cases but not in others. Most evidence suggests that caffeine is rated as having the most desirable and pleasant reactions in heavy coffee drinkers, particularly after they have not had any coffee for several hours and some people show normally show dysphoric effect for coffee in general. This finding suggests that many of the reinforcing effects of caffeine stem from its ability to terminate caffeine withdrawal. However, research indicates that the average caffeine intake of coffee consumers does not predict the occurrence of withdrawal When coffee consumers are tested with caffeinated and decaffeinated coffee, they were more likely to self-administer caffeinated coffee. The effects of caffeine vary considerably among individuals in terms of wakefulness, psychomotor coordination, mood alterations, and autonomic nervous system response. Two cups of coffee, which contains ~ 150 mg of caffeine, has the mood-elevating and fatigue-relieving properties of threshold doses of amphetamine (~ 2 to 5mg) However, larger doses generally do not have more of a mood-elevating effect, and 7 to 10 cups of coffee may cause insomnia, restlessness, mild sensory disturbances, or muscle tenseness ( collectively called caffeinism), or may precipitate anxiety or panic attacks in susceptible individuals Caffeine typically raises BP slightly in both men and women, but apparently via different mechanisms. Heart rate changes are variable and with some caffeine doses, may actually decrease. Increases in galvanic skin conductance level and reactivity are generally noted. www.notesolution.com
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