Causes of OCD

There has been a good deal of research carried out over the past few years
regarding the causes of OCD. It has been speculated that there might be several
kinds of OCD and that, in particular, OCD that starts in childhood may be different
from that which begins in adulthood.

Chemical and brain dysfunction

One cause that is gaining ground concerns the probability that there is a level
of brain dysfunction in many OCD sufferers.

This does not mean that people with this problem have damaged brains or that
their reasoning functions are inferior to those who do not have OCD.

The chemical messenger, Seretonin seems to be heavily involved.  Seretonin
is a chemical called a neurotransmitter that allows nerve cells to communicate
with each other by working in the space between nerve cells, called the
synaptic cleft.  According to research, Seretonin is involved with
biological processes such as mood, aggression, sleep, appetite and pain.
It also seems that Seretonin is capable of connecting to nerve cells in the
brain in many different ways and so can cause many different responses.
It is not even fully established if it is all or part of the Seretonin chemical
or another chemical entirely acting on it; or a malfunction in one or more of
the receptors in the brain that Seretonin attaches to that causes the OCD

Brain scans have also shown that people with OCD often have abnormalities
within the brain, particularly in the orbital cortex (the part of the brain
above the eyes) and in deeper structures such as the Basal Ganglia and
Thalmus.  This research suggests that the communication between these
parts of the brain is not functioning correctly.  Basically, when anxiety
rises in the OCD sufferer, a circuit of inappropriate response happens between
these parts of the brain.

As the deeper, primitive part of the brain is not the part that is involved
with reasoning, it is not possible to ‘talk yourself’ out of an over response.
As the various parts of the brain have different levels of priority and
urgency, the ‘message’ being sent can cause great confusion to the reasoning
brain, the Cortex.

For example, the Thalmus processes sensory images coming to the brain from the
rest of the body, while the Caudate Nucleus, part of the Basal Gangli in the
centre of the brain controls and sorts sensory information and does thought
filtering.  When these messages are being misinterpreted, ‘misfiring’, the
thinking part of the brain is naturally confused and is responding chemically
to a threat perceived by the primitive, non-reasoning part of the brain with
rational doubt of the threat’s danger, but a major need to response as if the
danger is real. In effect, the Caudate Nucleus is letting unnecessary thoughts
and impulses through to the Cortex where the thoughts and emotions combine; and
an over active Cingulate Nucleus at the brain’s centre, which helps shift
attention from one thought or behaviour to another, becomes over active and
gets stuck on certain behaviours, thoughts or ideas. The Cingulate is that part
of the brain which tells the OCD sufferer that something terrible will happen
if the compulsions are not carried out.

So, with the Thalmus sending messages that makes this person very (probably
very uncomfortably) aware of everything around him or her and the Caudate
Nucleus opening the floodgates to intrusive thoughts, the Cortex is perceiving
major problems that feed in to the ‘fight or flight’, or major danger response.
The Cingulate Gyrus then demands that compulsions are carried out to relieve
the terrible anxiety feelings.

  • It can be seen from this that,
    trying to ‘think’ oneself free of ocd within the problem and using the
    problem’s own parameters, is not a reasonable option.
  • It is important to be able to
    differentiate between what the primitive and rational brains are saying is the
    true situation.
  • Bear in mind that the part of the
    brain responsible for ocd, functions very much on the same emotional level as
    that of a two year old. Reasoned argument is, therefore, pointless.


Within the groups, we sometimes talk about the OC response as a huge
two-year-old.  It cannot be reasoned with, but it demands notice and is
powerful enough to insist.  Then, as with any irrationally demanding
two-year-old, one has to use techniques to win it round or divert its
needs.  To this end, gradually increasing exposure to the problem may be
used, but it should never be forgotten that this OC response is not malign, it
means no harm, but it cannot be reasoned with intellectually. So anyone
experienced in dealing with small children might usefully include these
child-teaching techniques, or appropriate versions of them, as part of a
recovery programme.  Common sense is a very useful tool in combating OCD.


Some research points to the likelihood that OCD sufferers will have a family
member with the problem or with one of the other ‘OCD –Spectrum’ of disorders.
These are, body dysmorphic disorder (excessive concern about minor or imagined
defects in appearance), hypochondriasis (fear of having a serious disease
despite tests and reassurance by medical professionals), binge eating and
trichotillamonia (pulling out scalp hair, eyebrows, eyelashes, body hair, even
that of others such as children or pets). However the possibility that it is
inherited genetically is not conclusive.  It does not follow, for example,
that identical twins will both have OCD (although there is an increased
chance), so genetics cannot be entirely to blame.

One American study suggested that up to 30% of teenagers with OCD had a member
of the immediate family with the problem or with obsessive symptoms. Other
studies tend to suggest that if a sufferer’s OCD began in adulthood there is
less chance of this person’s offspring contracting it than if the problem was
contracted in childhood, specifically if the latter is the type of OCD that
tends to start in childhood (if there are different types).

Other research suggests that if one parent has OCD the chances of the child
having it are between 2% and 8%.  Here again, if the parent has family
members with the problem, the chances of the child contracting it increase and
if the parent has no family history of OCD, they decrease. A point to bear in
mind concerning children is that OCD can involve increased stress and
poor eating habits, particularly if the problem relates to food.  Children
with OCD might then not do too well physically and be prone to stress related
problems like headache and upset stomach.


A streptococcal infection of the throat is known to occasionally result in the
body confusing healthy cells with the infection and causing cellular
damage.  If this has happened with the brain, the body’s infection
fighting system can attack the outside of nerve cells in the Basal Ganglia part
of the brain with the result that OCD symptoms occur.  Some research
suggests that these symptoms don’t seem to last very long and the occurrence of
this ‘infection OCD’ seems to be very rare.

‘Strep throat’ is a specific infection usually found in children, and a general
‘sore throat’ does not mean this infection is present. Symptoms of strep vary a
lot but can include a bright red throat, high fever, tender and swollen lymph
nodes under the jaw, ear pain, white pus on the tonsils and dark red spots on
the back of the throat. Blocked or runny nose is not usually present and some
children hardly get any symptoms. Scarlet fever is one form of strep infection
and in this case there will be a fine red rash on the body, probably starting
with the upper body.  Strep infection can also lead to rheumatic fever or
kidney problems when not treated.  Penicillin seems to be the treatment of
choice at present.

If OCD results from a strep throat infection, the symptoms seem to start
quickly, probably within one or two weeks.


People with depression sometimes develop OC symptoms, and those with OCD very
often develop depression.  Dealing with both together is very difficult
without clinical intervention and it is notoriously difficult to undertake an
exposure programme while the depression is high.


This is the theory that states that disturbances in early sexual or general
development and unconscious wishes are at the heart of OCD. Regarding
development, the theory is that conflict between the thinking and reasoning
part of the mind and the part that wants it’s own way is dealt with in an
unstable way by the child and that causes mental problems in later life.
An example might be a compulsive checker of taps who, according to this theory,
wanted to flood the house as a child. With unconscious wishes, the theory could
be that, for example, the person who fears running over people in his car
really wants to do this. To keep the awareness out of his consciousness he uses
a huge amount of energy which gives the thought an obsessional quality.

These theories are not given much weight nowadays, although it is always useful
to be aware of the role of guilt feelings in OCD.


Guilt and shame seem to occur strongly in some people’s OCD, particularly that
of young people. ‘Tendency’ also seems to play a large part in this disorder,
as in children inheriting a disposition towards OC problems or learning anxiety
and guilt from parents or ‘significant other’ people in their lives. Why some
people have a tendency towards neurosis and others don’t is very difficult to

Children tend to feel guilt about their natural needs from a very early age and
it can be said that guilt and feeling over-responsible is endemic to obsessive
people of our culture. This will be looked at in more detail in two further
leaflets in this series: ‘Guilt and Shame’, and ‘Obsessional Thinking’.

The cause of OCD is probably a mix of many factors described above, including
neurobiological, environmental influences and the way we think.

This article is for information only and should not be used as a definitive or
medical appraisal of the causes of OCD. It is also a non-profit publication.