; OCD _Obsessive Compulsive Disorder_
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OCD _Obsessive Compulsive Disorder_

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									        OCD
(Obsessive Compulsive
      Disorder)
       Summary of topics
Introduction – from late 17th century
Links to other conditions
Basal Ganglia evidence
Serotonin/Dopamine
Oxytocin
Evolutionary view
Cognitive view - memory
Conclusion
        OCD:Introduction
Obsessions = thoughts (eg harming
others), intrusive blasphemous thoughts
more common in Roman Catholics
May have counting ritual to prevent…
Recurrent, persistent and irrational
impulses, thoughts or images that cause
anxiety or distress and are not just
excessive worries of real life (DSMIV)
         OCD:Introduction
Compulsions = actions (eg washing, tidying,
may be localised)
Ritualistic, repetitive, purposeful behaviours or
mental acts that an individual feels compelled to
perform in response to an obsession (DSMIV)
Also seen in other conditions like depression
(cause or effect?)
Role for instrumental conditioning (negative
reinforcement)
                Incidence
Neurosis; incidence about 2.5%, 10% subclinical
Reduction of sanitised ritual (Smay, 2003)
Typical onset young adulthood, but about 40%
show childhood symptoms
Average lifetime prevalence of 1-3% in adults
PANDAS – pediatric autoimmune
neuropsychiatric disorder, group A β haemolytic
streptococcus
Tonsillitis
               Incidence
More males than females in childhood
– 2:1 to 3:2 ratios
– Earlier age of onset for males
– Males have more severe symptoms
More females than males in adults
Cultural variations of OCD (NB more
similarities though)
– Africa – checking
– America - cleaning
        What tends to happen….

The person attempts to
ignore or suppress those
impulses/thoughts/images or
neutralise them with some
other thought or action
Interference with Normal
Functioning
Personal Distress
Deviance from Social Norms
The person recognizes that
those are a product of their
own mind i.e. neurosis rather
than psychosis
             Patterns of behaviour
                           Type of compulsions
Type of obsessions
                              Excessive or ritualistic
 – dirt and germs
   (40%)                      handwashing, bathing,
 – Worries about              showering, grooming
   something terrible         (85%)
   happening (24%)            Repeating rituals, e.g.,
 – Worries about              going in or out of a door
   symmetry, order            (51%)
   and exactness
   (17%)                       checking compulsions
 – Sexual images              gas, locks (46%)
   (guilt)                    Ordering or arranging
                              (17%)
Males – high                  Counting (18%)
prevalence of                 Hoarding or collecting
checking                      old newspapers, empty
Females – high                boxes (6%)
prevalence of
washing
                         NUMBER MAGIC……
             OCD:links
Family (genetic?) association with
Tourettes’s
Smith (2007)Sapap3 gene in mice =>
SAPAP3 protein. When switched off,
mice showed increased axiety and
compulsive grooming
Ozaki et al. (2003) – gene mutations
found in gene for serotonin re-uptake
Depression and anxiety common – about
50% is psychological response to OCD
             OCD:links
Anorexia – McKean and Murry (1987) –
increase in anxiety and eating disorders in
first degree relatives. Anorexia –
obsessive about food, ritual eating,
magical thinking
 epilepsy – Stephen, OCD remained
although epilepsy under control
              OCD:links
Sydenham’s chorea (form of rheumatic fever,
aka St Vitus’ dance), about 30% have OCD
Post-encephalitic Parkinsonism – inflammation
of the brain => damage, also Herpes virus
Alteration of the will in Parkinsonism
Post-partum mothers
Trichotillomania
Body Dysmorphia
Hypochondriasis
  OCD: Basal Ganglia Hypotheses

OCD result of Malfunctioning ‘instinct-
related’ system
Basal Ganglia (lower nerve knot),
especially Caudate nucleus (also Putamen
and Globus Pallidus)
Serotonin = key transmitter (in this system,
serotonin seems to ‘balance’ dopamine)
OCD helped by raising 5-HT (shorthand
for serotonin) levels
  Section through monkey brain showing
  the basal ganglia structures

                              Stained for acetyl
                              cholinesterase
Collection of sub cortical
nuclei in the forebrain.
The Basal Ganglia don’t
initiate movement, but
send messages from the
thalamus and midbrain to
the cerebral cortex = relay
station
      OCD: Basal Ganglia cont.

Poisoning/stroke etc. can cause OCD
Parkinson’s, Sydenham’s, Tourette’s
– Involve degeneration of dopaminergic
  neurons in the midbrain that send axons to
  parts of the Basal Ganglia, e.g. the substantia
  nigra, caudate nucleus and Putamen
Stroke to Caudate nucleus or to cingulate
gyrus or frontal cortex can => OCD
– Glutamate overactivity, reduced blood supply
    OCD: Basal Ganglia cont.
PET shows bilateral Caudate and left
orbital gyrus are over active in OCD
– Continually send messages of ‘dread’
– not switched off
rCBF shows right caudate, left anterior
cingulate gyrus and bilateral orbital area
       OCD: Basal Ganglia cont

Worst 35% OCD helped by bilateral
cingulotomy/cingulectomy. This Disconnects the
cingulate cortex from the orbitofrontal areas –
destruction of cingulum bundle, a group of axons
which connect the prefrontal and cingulate
cortex with the limbic cortex of the temporal lobe
Insel (1992) proposed a model of the system:
frontal-striatal-thalamic loop, lesioning
Cingulate cortex = part of emotional systems i.e.
the limbic system, disgust
 Model of frontal-striatal-thalamic
loop – both overactive and linked!

                  Orbito frontal cortex/
 Worry signals                              Re-enforces worry, so
 from cortex go   Pre-frontal cortex        goes round the loop
 to striatum                                again


                                            Thalamus
Caudate nucleus     Inhibits thalamic
                    inhibition, so
Putamen             worry continues
Globus Pallidus
   = striatum            Cingulate cortex      Racing heart
                                               etc.
Just to remind you of
intro to psychobiology
session
           OCD: Serotonin
Only effective drugs are SSRI’s (serotonin
specific reuptake inhibitors)
Clomipramine first (still seems best), Prozac
(fluoxetine), but stop taking them, and OCD
symptoms return
NB SSRI’s take 2-3 weeks for clinical effect, but
the effects occur sooner….
CBT – changes neurochemistry and linking in
frontal-striatal thalamic loop
– Baxter (1999) – Anolis lizard, increased 5HT if won
  fight, decreased if lost. Support for environmental
  effects on neurotransmitter levels.
           OCD: Serotonin
David – used different illegal drugs to control his
OCD symptoms.
Which of the following should be better for
reducing OCD specifically? Hint there are 2!
–   Amphetamine
–   Cocaine
–   Valium
–   LSD
–   Ecstasy
–   Heroin
        OCD: Dopamine
Balances Serotonin in Basal Ganglia
Dopamine agonist Quinpirole increased
checking behaviours in rats, but it
decreased grooming.
Checking and washing different
neurochemical profiles?
Rent et al. (2005) – Hyper-dopaminergic
mutant mice increased grooming, and
FAPs were harder to interrupt
          OCD: Oxytocin
Neurosectretory nanopeptide
Affiliation
Bonding
Sexual and reproductive behaviours
Grooming
Cerebrospinal fluid analysis suggests
some OCD may be linked to oxytocin
dysfunction
       OCD: Evolutionary view
Key = ancient, species specific
fixed action patterns (FAPs)
e.g. grooming are being
triggered inappropriately
Rats – always groom head to
tail
Barber mice
Mineka – phobias
      OCD: Evolutionary view
Hormonal cycles in adult females influcence
severity. Increased need for hygeine?
– Progesterone increases nesting in mice
5-HT influences FAP’s etc. in mammals
Basal Ganglia mediate FAP’s in manny
mammals. Wise and Rapoport (1989), detection
mechanism in BG to recognise sign stimuli, then
releasing mechanism for the appropriate species
specific response
      OCD: Evolutionary view
Involuntary Risk Scenario Generating system
(IRSGS)
–   Off-line risk avoidance
–   Like antibody generation
–   Immunisation against risk?
–   Obsessions = risk scenarios
–   Compulsions = risk prevention routines
–   Link to PTSD?
Criticism – co-occurrence of risky behaviours
So, is OCD Just exaggerated normal
behaviour??
Extreme end of an adaptive trait..
        OCD in animals?
Stereotypical behaviours
Zoo animals – pacing, and other OCD-like
behaviours
Paw licking in dogs Labrador retrievers,
Doberman pinschers, Weimaraners, Shar-
Pei, and Dalmatians seem to have
obsessive licking problems – genetics?
Excessive grooming or sucking in cats
Feather pulling in birds
        OCD in animals?
May do in private – realise not usual?
Respond to antidepressants e.g.
cloripramine
Co-morbid with other disorders, like
separation anxiety
Stress increased the expression of the
behaviours
      OCD and Cognition
Memory functioning – mnestic deficit,
epistemolgical sense deficit
Impaired memory for actions
Poor visual memory – delayed
reproduction of abstract line drawing was
poor
                          Rey figure
       OCD and Cognition
Difficulty distinguishing the real from the
imagined – link to Parkinsonism, the will,
lack a feeling of personal involvement
Not reassured by evidence of their eyes
Catastrophic schemata
BG important for visuo-spatial functioning
May only relate to checking aspects of
OCD?
         OCD: Conclusion
Biological basis plausible
rCBF and PET scans etc. indicate role for BG,
cortical striatal thalamic loop
Neurotransmitter and drug effects suggest
serotonin and dopamine are important
May also be roles for oxytocin and glutamate
Could be maladaptive end point of an adaptive
trait (FAPs, IRSGS)
Links to cognition and memory, CBT
Shows the value of multiple perspectives

								
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