Psychopharmacology Flashcards
Define psychopharmacology:
the study of the effects of drugs on cognition, mood, and behaviour
Why is psychopharmacological research difficult?
we only know what we happen to have found out so far
What is psychopharmacological research useful for?
drugs can be used to study functions of endogenous neurotransmitter systems (NTs). investigation of drug effects can lead to the development of treatments for medical/psychological conditions such as Alzheimer’s, schizophrenia and depression.
What is a confound?
a confound is a potential alternative cause of what appears to be a drug effect
How would you control for the following confounds?
A-natural recovery
B-expectation of drug effect
C-expectation of side effects
A- a comparison with a no treatment group
B- comparison with placebo and blinding of conditions
C- comparison with an active placebo with similar noticeable side effects
Describe a Randomised Control Trial (RCTs):
this involves a control condition and a random assignment of participants to groups
Describe Blinding of Conditions:
a blind study where participants are unaware of group assignment or a double-blind where the participant and researcher are both unaware of group assignments
Describe Open-Label Trials:
these are studies without blinding, they may still have a control group
What heightens the risk of a trial being unblinded?
when the effects are detectable and so participants can begin to guess which group they are part of
Describe a between-subject design:
comparison between participants versus a control group
Describe a within-subject design:
comparison between two conditions with the same participants
Why is a washout period helpful?
this allows drugs to leave the system before the next trial in order to not carry over effects
What is a phenomenological method of measuring drug effects?
self reported changes in subjective experience and mood
how can the phenomenological method of measuring drug effect reduce its susceptibility to bias?
by using a double blind technique
How can you measure changes in physiological activity and why is it important?
via methods such as fMRI and EEG. This is important because we can investigate the effects of drugs on people
Which tasks can be used to measure drug effects?
simple and choice tasks, vigilance, memory, and problem solving tasks
What changes of behaviour are indicative of drug effects?
changes such as social cooperation, aggression, hyperactivity etc.
What is the aim of neurocognitive models?
neurocognitive models aim to explore relationships between specific neurotransmitter systems, cognitive processes and subjective experiences
What could a neurocognitive model centre around?
the model could be of a type of drug effect (e.g. stimulant, sedative, psychedelic), or it could be of a neuropsychiatric condition (e.g. ADHD, depression, schizophrenia)
What are examples of neurocognitive models?
-noradrenaline on alertness and attentional focus for ADHD
-dopamine on stimulus salience for schizophrenia
-serotonin on emotional info processing for mood disorders
what is the function of:
1)dendrites
2)cell body (soma)
3)axon
4)action potential
5)enzymes
6)axon hillock
1-receive NTs from other neurons (chemical signals)
2-includes the nucleus and controls cell activity
3-allows electrical signal (action potential) to travel to axon terminal
4-integrate multiple excitatory and inhibitory signals to determine whether an action potential is generated
5-control synthesis of neurotransmitters stored on vesicles and released from axon terminal
6-action potentials are triggered here is there is sufficient depolarisation
What indicates sufficient depolarisation?
+ relative to -
what is the difference between excitatory and inhibitory?
excitatory increases the likelihood of a receiving neuron producing an action potential, and inhibitory decreases the likelihood
What are three steps of endogenous processes?
1- synthesis by enzymes and packaged in vesicles
2-release and bind with postsynaptic receptors
3- deactivated via presynaptic reuptake or broken down by enzymes
How do NTs influence ion channels?
NTs influence by opening and closing ion channels allowing electrically charged ions to move in or out of the post synaptic cell making it more or less likely to fire
What effects do some NTs have that are not direct?
modulating the effect of other NTs on ion channels or leading to synaptic changes.
What does the effect of NTs depend on?
receptor types
What happens in NT deactivation?
NT detaches from receptor and is transported back (reuptake), or broken down by enzymes
What is the difference between agonist and antagonists?
agonists mimic or enhance the effect of a NT whereas antagonists block or reduce the effect of NT
How do psychoactive drugs work and how can they influence NTs?
they interact with NT systems and can influence NT synthesis, storage, release, deactivation, and receptor interactions
Name two major neurotransmitters and how they work together:
GABA= main inhibitory NT released by 40% neurons
Glutamate- main excitatory NT released by 50% neurons
they work in opposition to maintain balance between inhabitation and excitation
What are examples of GABA agonists and what effects do they have?
Benzodiazepines, barbiturates, and alcohol.
They can reduce anxiety (specifically anxiolytic), reduce arousals (sedatives), and can promote sleep
What are BZDs commonly prescribed for?
anxiety and used as a pre anaesthetic for surgery
What are Barbiturates typically used for?
general anaesthetic, induce comas and treat epilepsy
What are two GABA antagonists?
stimulants: flumazenil and picrotoxin
What is an antidote for a BZD overdose?
flumazenil, blocks BZD site on receptors
What is a purpose of flumazenil besides treating overdoses?
it can reverse sedation after surgery
What is an antidote for a Barbiturate overdose?
picrotoxin
what could be used to induce a seizure ?
picrotoxin
What is ibotenic acid and how can it be dangerous?
a glutamate agonist. can kill nerve cells through over excitation
What is ketamine and how can it be used?
a glutamate antagonist, blocks excitatory effect of glutamate. can be used as a sedative and anaesthetic
Describe NMDA:
a receptor sub type. NDMA receptors are important in initiating long term synaptic changes necessary for learning. NMDA is also implicated in drug addiction, schizophrenia, and epilepsy
What is ARAS?
Ascending Reticular Activating System. Regulates general levels of cortical arousal, alertness, and consciousness.
What is ARAS the source of?
major excitatory neurotransmitters Noradrenaline (NA) and Acetylcholine (ACh)
How does ARAS communicate with other brain regions?
The axons of ARAS project from brain stem to higher cortical regions via thalamus
What was suggested by Eysenck (1967) regarding ARAS and extraversion?
suggested a link between ARAS and extraversion. extraverts have low resting ARAS activities and so seek out more stimulation, while introverts have high resting activity and so they avoid overstimulation
What is the difference in distribution between Glutamate and Gava, and Noradrenaline and Acetylcholine?
cells that produce glutamate and Gava can be found all over the brain and cortex. NA and ACh are not widely distributed and so are in specific regions
Describe the nature of the Anterior system and the Posterior system:
Anterior system= frontal. top down system (cognitive input first), voluntary, controlled, task and goal driven, associated with executive functioning
Posterior system= parietal. bottom up system (sensory input first), involuntary, automatic, stimulus driven attention, orienting reflex
Explain what is meant by Alertness, Attention, and Arousal:
Alertness= generalised readiness to process stimuli and respond. measured by subjective feelings or simple psychomotor tasks
Attention= enhanced processing of specific/selected stimuli. measured by behavioural performance
Arousal= physiological activation in autonomic nervous system or central nervous system
How is alertness measured through simple detection/reaction time tasks?
Mean reaction time depends on average alertness during the task or temporary increase in alertness following warning cues
How is alertness measured through vigilance (continuous performance) tasks?
person is told to respond only to pre specified target stimulus/sequence. The targets are rare and the presentation is rapid. Also involves the Anterior system. Measures average reaction time to targets, errors of omission (missed targets), and errors of commission (false alarms)
Why are vigilance tasks harder than simple detection tasks?
vigilance tasks require sustained attention and so are more cognitively demanding.
What are stimulants and what are some examples?
drugs that increase alertness and arousal; caffeine nicotine, amphetamines, methylphenidate aka Ritalin
What do stimulants do to noradrenaline and acetylcholine?
they mimic or enhance the effects of noradrenaline and acetylcholine. they are noradrenergic or cholinergic agonists.
What are sedatives and what are some examples?
they are drugs that reduce alertness and arousal. These include GABA agonists, noradrenergic beta blockers, and cholinergic antagonists
Where is the main source of Noradrenaline and how does it move around the brain?
The Locus Coeruleus (LC, blue spot) in the brain stem are the main source of NA. They project to higher brain areas including via the thalamus
What are the effect of drugs that increase NA-ergic activity?
psychostimulants increase alertness whereas anxiogenic have anxiety producing effects
Describe Amphetamines?
Amphetamines are synthetic drugs produced from ephedrine and pseudoephedrine. they increase the release and block the reuptake of noradrenaline and dopamine
What are the acute effects of Amphetamines?
they have subjective effects. can include feelings of energy and alertness, however increase anxiety as a high dose
What are the effects of Amphetamines on task performance?
Low doses improve performance in psychomotor and vigilance tasks. High doses impair task performance and increase distractibility
Explain Yerkes-Dodson Law regarding arousal (1908):
Inverted U relationship between arousal and task performance. Under arousal and over arousal can both impair performance. increasing arousal with a psychostimulant can improve performance if the arousal is low, or impair the performance if the arousal is high. This may be due to arousal narrowing attentional focus which can be too narrow for optimal performance on complex tasks.
What are the effects of drugs that reduce NA ergic activity?
sedative affects reducing alertness and anxiolytic (anxiety reducing) effects.
Describe Noradrenergic beta blockers:
e.g. propranolol which is mainly used clinically for effects on blood pressure and heart). They are B receptor Antagonists.
What neurons release acetylcholine?
cholinergic neurons
How is acetylcholine sent throughout the brain?
Cholinergic nuclei in upper brain stem project to thalamus and regulate arousal and sleep/wake cycle.
What does acetylcholine activate:
systems associated with alertness, attention, learning, and memory
What are cholinergic inhibitors used for?
they are used in Alzheimer’s treatment (ACh) because the cells in the basal forebrain are lost in the disease. inhibitors increase ACh availability
What do cholinergic receptor agonists do and what is an example?
e.g. nicotine. Mimic the effects of ACh at their receptors increasing subjective alertness
What do cholinergic antagonists do?
they block the effects of ACh at receptors therefore reducing subjective awareness
In what way are cholinergic antagonists similar to Alzheimer’s?
they cause general cognitive impairment (delirium) which is similar to Alzheimer’s symptoms.
What is Scopolamine?
Scopolamine is a cholinergic antagonist found in various toxic plants e.g. deadly nightshade family
Explain Wesnes et al. (1988) study with scopolamine:
Wesnes gave scopolamine or a placebo and measured the task performance on various cognitive tasks. people on scopolamine felt less alert (in self rating), missed more targets in vigilance tasks, responded more slowly in vigilance tasks, and had poorer memory performance in word recall.
What amount of population does ADHD effect?
estimated to effect about 5% of population. More frequently detected in males than females, but this doesn’t mean it is definitely more common in males.
When are ADHD symptoms more prevalent?
characteristics are first present in childhood and in 50% of cases persists into adulthood
What are the main ADHD symptoms?
inattention, hyperactivity, impulsivity, forgetfulness, distractibility
How can ADHD be treated with drugs?
often treated with psychostimulant drugs such as Adderall (amphetamine), and Ritalin (methylphenidate). they increase levels of noradrenaline and therefore dopamine in the brain
What are newer drug treatments for ADHD?
newer drug treatments more selectively target noradrenaline levels (e.g. atomoxetine, a noradrenaline reuptake inhibitor) as opposed to also effecting dopamine
Describe Zeiner et al. (1999) study on response to methylphenidate in boys with ADHD:
36 boys aged 7 to 11 following a double blind placebo controlled procedure with a within subjects design. Three weeks of daily treatment, one week washout period. Assessments were carried out in the final week of each treatment.
What were the findings of Zeiner et al. (1999) study on Ritalin in boys with ADHD?
found that vigilance was improved (fewer missed targets on tests), also increased performance on working memory tasks, and decreased reported hyperactivity and conduct problems
Why would a stimulant drug reduce hyperactivity?
if ADHD involves abnormally low levels of intrinsic arousal, hyperactivity might be aimed at increasing arousal to a more optimal level as a behavioural response. this could reduce the need for hyperactivity as well as improve cognitive functioning
What is a theory to do with ADHD and extraversion?
ADHD may be an extreme end of the extraversion personality dimension.
What are the three Dopaminergic systems?
Nigrostriatal
Mesocortical
Mesolimbic
describe the nigrostriatal pathway and its functions:
substantia nigra to striatum (dorsal).
Motor Control and indirectly Executive function via fronto-striatal circuity
describe the Mesocortcial pathway and it’s function:
ventral tegmental area to pre frontal cortex.
Executive function
Which pathways is Parkinson’s disease related to?
Nigrostriatal system and Mesocortical system