Transcript Functional neuroimaging of anxiety

Functional neuroimaging of
anxiety
A meta-analysis of emotional
processing in PTSD, social
anxiety disorder and specific
phobia
Objective
• Find common and disorder-specific
functional neurobiological deficits in
anxiety disorders.
• Compare findings to systems engaged
during anticipatory anxiety in healthy
subjects.
Method
• A comparative quantitative metaanalysis of FMRI and PET of studies:
- Post traumatic stress disorder
- Social anxiety disorder
- Specific phobias
- Anticipatory anxiety in healthy subjects
PTSD
• Anxiety disorder developed after
psychological trauma.
• Involving reexperience. (nightmares and
flashbacks)
• Avoidance of triggers. (Stimuli that is
associated with trauma)
• Symptoms of increased arousal. (Sleep and
concentration problems)
• Lasting more than one month.
Social anxiety disorder
• Fear regarding social activities.
Of being humiliated or embarrassed by
their actions.
• Leading to avoidance of social
situations.
Phobia
• Form Greek “phobos” meaning fear.
• Irrational, intense, persistent fear of
certain situations, objects, activities or
persons.
• Excessive desire to avoid the feared
subject.
Anxiety
• Previous negative experience.
• Stimulus associated with this
experience trigger defensive behavior.
• Defensive behavior involve avoiding
triggers.
• Lead to impaired life quality if
excessive.
Maintaining anxiety
• Operant conditioning;
• when we see or encounter something associated with
a previous traumatic experience, anxious feelings
resurface.
• We feel temporarily relieved when we avoid
situations which make us anxious, but this only
increases anxious feelings the next time we are in the
same position, and we will want to escape the
situation again and therefore will not make any
progress against the anxiety.
Fear in the brain
• It has long been known that fear is
associated with activation of amygdala.
• Studies have shown inconsistencies in
the activity of other nuclei during fear
response in humans.
Amygdala
• Research indicates that, during fear conditioning,
sensory stimuli reach the Amygdala where it forms
associations with memories of the stimuli.
• Involved in the genesis of many fear responses,
including freezing, tachycardia, increased respiration,
and stress-hormone release.
• Damage to the amygdalae impairs both the
acquisition and expression of Pavlovian fear
conditioning
• The amygdalae, especially the basolateral nuclei, are
involved in mediating the effects of emotional arousal
on the strength of the memory for the event
Lobus insularis
• The insula is believed to process convergent
information to produce an emotionally
relevant context for sensory experience.
• Functional imaging experiments have
revealed that the insula has an important role
in pain experience and the experience of a
number of basic emotions, including anger,
fear, disgust, happiness and sadness.
Results PTSD
• Hyperactivity in Amygdalae,
Parahippocampal gyrus, Insula, Inferior
parietal lobe, Mid-cingulate and
Precuneus cortex.
• Hypoactivity in many cortical areas and
some amygdalar nuclei.
Results social anxiety disorder
• Hyperactivity in amygdalae,
parahippocampal and fusiform gyrus,
globus pallidus, insula, inferior frontal
and superior temporal gyrus.
• No hypoactivity.
Results specific phobia
• Hyperactivity in amygdalae, fusiform
gyrus, globus pallidus, insula, inferior
frontal and superior temporal gyrus.
• No hypoactivity.
Discussion
• Amygdala and insula are the only two
areas showing consistent hyperactivity
in the three disorders.
• PTSD is a complex disorder where fear
is only one component.
• Social anxiety and phobias may be
more readily described as intense fear.
Conclusion
• Social anxiety disorder and Phobias are
comparable with fear in healthy
subjects.
• PTSD however has fear as one
component, but has a other
components too.