PET Application In Psycology
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Transcript of PET Application In Psycology
PET Application in Psychiatry
PET Application in Psychiatry
Ramin V. Parsey and J. John MannRamin V. Parsey and J. John Mann
By Dan Diner
PETPET nuclear medical imaging technique Produces 3D images(maps) of functional
processes in the body Scientists inject short half-life radioactive
isotopes(tracers) into body, then detect gamma rays
nuclear medical imaging technique Produces 3D images(maps) of functional
processes in the body Scientists inject short half-life radioactive
isotopes(tracers) into body, then detect gamma rays
isotope goes through positron decay emits a positron(antimatter of electron) Travels a few mm and annihilates with an
electron, producing gamma photons moving in opposite directions*
The annihilation is detected by the scintillator material in the scanning device, which sends off a burst of light that is caught by the photomultiplier tubes
isotope goes through positron decay emits a positron(antimatter of electron) Travels a few mm and annihilates with an
electron, producing gamma photons moving in opposite directions*
The annihilation is detected by the scintillator material in the scanning device, which sends off a burst of light that is caught by the photomultiplier tubes
[15O]-Water[15O]-Water
Half-life of 2 minutes Used to image blood flow Use of it also indicated pre-frontal cortex
deficit in depression
Half-life of 2 minutes Used to image blood flow Use of it also indicated pre-frontal cortex
deficit in depression
18F-FDG(fluoro-2-deoxyglucose)
18F-FDG(fluoro-2-deoxyglucose)
used for the assessment of glucose activity in brain (and heart). Used for finding tumors.
Patients fast 6 hours beforehand After injection, patient waits 1 hour Taken in by tissues with high metabolic activities- such
as tumors High for tumors because not they don’t listen to body.
Grow out of control. More Cells. Patient does keeps physical activity to a minimum so as
to minimize uptake of radioactive chemicals into muscles
used for the assessment of glucose activity in brain (and heart). Used for finding tumors.
Patients fast 6 hours beforehand After injection, patient waits 1 hour Taken in by tissues with high metabolic activities- such
as tumors High for tumors because not they don’t listen to body.
Grow out of control. More Cells. Patient does keeps physical activity to a minimum so as
to minimize uptake of radioactive chemicals into muscles
Neuroimaging studies generally agree that mood disorders link with functional deficits but disagreed about structal deficits:
Study with depressed patients found 11/12 had low regional cerebral metabolic rate of glucose
Other studies studies claim that differences in key brain region volumes play roles in mood disorders
Neuroimaging studies generally agree that mood disorders link with functional deficits but disagreed about structal deficits:
Study with depressed patients found 11/12 had low regional cerebral metabolic rate of glucose
Other studies studies claim that differences in key brain region volumes play roles in mood disorders
SerotoninSerotonin
Neurotransmitter in CNS Regulates anger, sleep, body temperature,
aggression, mood, appetite, vomiting, and sexuality
Deficits in Serotonin are associated with extreme mood disorders, such as Obsessive Compulsive Disorder, bipolar disorder, and clinical depression
Neurotransmitter in CNS Regulates anger, sleep, body temperature,
aggression, mood, appetite, vomiting, and sexuality
Deficits in Serotonin are associated with extreme mood disorders, such as Obsessive Compulsive Disorder, bipolar disorder, and clinical depression
Cont.Cont. Abnormal 5-HT transmission is thought to cause
major depression In postmortem studies, less serotonin transorter
binding was found throughout the dorsal(upper)-ventral extent of the prefrontal cortex and in the brainstem of people with episodes of major depression
Found lower 5-HT transporter binding in midbrain, amygdala, and ventral striatum, but not the thalamus
Abnormal 5-HT transmission is thought to cause major depression
In postmortem studies, less serotonin transorter binding was found throughout the dorsal(upper)-ventral extent of the prefrontal cortex and in the brainstem of people with episodes of major depression
Found lower 5-HT transporter binding in midbrain, amygdala, and ventral striatum, but not the thalamus
The lab found that depressed people's prefrontal cortex responds poorly to forced brain activity using serotonin
this suggests that pre-frontal cortex might be malfunctioning in depressed people
Fenfluramine(drug) was used as the challenge. It is supposed to activate brain activity everywhere in the brain
The lab found that depressed people's prefrontal cortex responds poorly to forced brain activity using serotonin
this suggests that pre-frontal cortex might be malfunctioning in depressed people
Fenfluramine(drug) was used as the challenge. It is supposed to activate brain activity everywhere in the brain
Why?Why?Hypotheses: Low 5-HT transporter binding could be due
to a functional change in the distribution of transporters
few serotonin nerve terminals due to fewer 5-HT neurons
Fewer terminals or fewer transporters per terminals
Hypotheses: Low 5-HT transporter binding could be due
to a functional change in the distribution of transporters
few serotonin nerve terminals due to fewer 5-HT neurons
Fewer terminals or fewer transporters per terminals
This is a PET McNeil scan result. McNeil binds to the serotonintransporter
(A) is an MRI (B) is a healthy person pet scan (C) is a depressed person
This is a PET McNeil scan result. McNeil binds to the serotonintransporter
(A) is an MRI (B) is a healthy person pet scan (C) is a depressed person
Notice that regions in a depressed person have much less serotonin transporterThis suggests that the serotonin system is different between healthy and depressed people. Future drugs could be made to stabilize this system.
SchizophreniaSchizophrenia
Mental disorder characterized by an impaired perception of reality
Often patients have hallucinogens Hypothesized to be caused by abnormal
Dopamine levels PET scan is often used to understand why
Mental disorder characterized by an impaired perception of reality
Often patients have hallucinogens Hypothesized to be caused by abnormal
Dopamine levels PET scan is often used to understand why
Dopamine System in Schizophrenia
Dopamine System in Schizophrenia
Dopamine- a neurotransmitter released by the hypothalamus that is also used as a medication that increases heart rate and blood pressure
Studies using [11C]-raclopride showed no result in D2 receptor binding abnormalities
but studies using [11C]-N-methyl-spiper-one showed that schizophrenics tended to have more D2 receptor binding
[11C]-raclopride have been used for same general purpose, and showed that decrease in [11C]-raclopride binding was proportional to amount of dopamine released
Dopamine- a neurotransmitter released by the hypothalamus that is also used as a medication that increases heart rate and blood pressure
Studies using [11C]-raclopride showed no result in D2 receptor binding abnormalities
but studies using [11C]-N-methyl-spiper-one showed that schizophrenics tended to have more D2 receptor binding
[11C]-raclopride have been used for same general purpose, and showed that decrease in [11C]-raclopride binding was proportional to amount of dopamine released
Psychotropic Drug DevelopmentPsychotropic Drug Development
[11C]-raclopride has been used to show that typical/classical antipsychotics (e.g. haloperidol) block over 70-80% of D2 receptors at doses with therapeutic effects. Atypical/newer generation antipsychotic block <70%. Atypical antidepressants produce much less side effects.
[11C]-raclopride has been used to show that typical/classical antipsychotics (e.g. haloperidol) block over 70-80% of D2 receptors at doses with therapeutic effects. Atypical/newer generation antipsychotic block <70%. Atypical antidepressants produce much less side effects.
Cont.Cont.
Antidepressants that enhance serotonin function(such as SSRI’s(Selective serotonin reuptake inhibitors)) have a therapeutic effects that evolve for weeks
SSRI prevents neurotransmitter from going back to the pre-synaptic neuron(reuptake)
Antidepressants that enhance serotonin function(such as SSRI’s(Selective serotonin reuptake inhibitors)) have a therapeutic effects that evolve for weeks
SSRI prevents neurotransmitter from going back to the pre-synaptic neuron(reuptake)
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