Formal thought disorders are disorders
of the form of thought and
can be recognised by speech, writing or occasionally behaviour. I have
included here disturbances in the stream of thought - how thoughts move
from one to another though these are not formal thought disorders.
Formal Thought Disorders
Flight of Ideas: the rapid movement from
one idea or concept to another, often without finishing the first.
- Clang associations: words
that sound the same - these
are used as jumping points to a new concept e.g. "... and then I rang
the bell sell - that's what I used to do - I
worked at a little shop in town
brown was always my favourite colour..."
- Puns: words that have several different meanings
used as jumping points to different ideas.
- Rhymes
These are mostly found in mania.
Loosening of associations: is a
loss of the normal structure of thinking. Thoughts move from one to
another by abnormal paths that are diffuicult or impossible to follow:
- 'Knights move' thinking
(derailment): the patients speech will suddenly move without
warning from one topic to another that is seemingly unrelated.
- Talking past the point
(Vorbeireden): the patient talks but never gets to the point -
they may get near it and veer of to another matter.
- Verbigeration: this is
the deterioration of speech to senseless repetition of words and
sounds. When especially severe it is called word salad.
These are mostly found in schizophrenia.
Overinclusion: this is the
inability to preserve conceptual boundaries, so that extra irrelevant
items become incorporated in concepts, rendering the patient's thinking
less precise and more abstract.
Neologisms: these are new words
created by the patient - often to describe symptoms. Before diagnosing
neologisms exclude dialect, jargon and foreign language words. Ask
where the word comes from. This is mostly found in schizophrenia.
Perseveration: this occurs when
one thing that has been said my be repeated, often several times. e.g.
a question may recieve a sensible answer but the next question yields
the exact same answer and the next and so on. This is mostly found in
schizophrenia.
Disorders in the stream of thought
Poverty
of thought: thoughts appear to be moving through treacle - they
are slow and thoughts are relatively few. This is noticed usually by
poverty of
speech and is
most often seen in depression.
Pressure of thought: thoughts
move rapidly from one to another and new thoughts occur with rapidity.
This is noticed usually by pressure of
speech and is most often seen in
hypomania or mania. It may be seen with amphetamine intoxication and as
a rare side effect of certain prescription medications.
Thought block: This is when
conscious thoughts stop - conversation will briefly cease if the
patient is talking. The patient is aware that a break in thoughts has
occurred and may form a
delusion
about why such as
thought withdrawal.
This is most often seen in schizophrenia.
Thought
insertion,
withdrawal and
broadcast are sometimes placed
within thought disorders - these are technically
delusions.
Differential Diagnoses
These are listed by ICD-10 names - where the DSM-IV name is different,
it is provided in brackets.
Bipolar
disorder: additional symptoms in the manic phase include wild
spending, increased libido, gambling, and delusions (usually
grandiose). In the depressive phase symptoms are as depression.
Dementia: additional symptoms
include memory loss; difficulty performing familiar tasks; problems
with language; disorientation to time and place; poor or decreased
judgement; problems with keeping track of things; misplacing things;
changes in mood, behavior or personality; Loss of initiative.
Depression: additional symptoms
include delusions (often nihilistic or of guilt), sleep dysfunction,
altered appetite, loss of libido, anhedonia and a subjective low mood.
Ask about suicidal ideation.
Schizophrenia: this is a
disease entity encompassing many many presentations. Always ask about
suicidal ideation. Schneiders first rank symptoms comprise four
characteristic hallucinations and 5 characteristic delusions. Any
one
of these is strongly suggestive of schizophrenia:
Four Hallucinations
Five Delusions
Substance related:
intoxication, withdrawal or psychosis from the use of. Obviously a
history of drug or alcohol use is vital in forming this diagnosis. Ask
about suicidal ideation.
