Thought disorders may be considered under the following headings:
form
content
flow
possession

There are three important disorders of the form of thought:
preoccupations:
these are thoughts or patterns of thinking which occur frequently but can be terminated if desired
one should always enquire about suicidal preoccupations in the depressed patient
preoccupations are a perpetuating factor in anxiety disorders e.g. thoughts about health in panic disorder
obsessive thoughts:
these are intrusive thoughts which are resisted by the patient
often the content of the thought is thought unacceptable
delusions:
in brief, a delusion is a false belief which is both culturally unconventional and held on inadequate grounds
delusions may be difficult to elicit as the patient either does not view them as unusual or is suspicious of the interviewer


Disorders of the content of thought include:
paranoid, including grandiose and persecutory thoughts
depressive, relating to the past, present or future
a depressed patient should always be asked about the suicidal content of their thoughts
other - e.g. obsessions, compulsions, hypochondriacal preoccupations

Disorders of the flow of thought fall into three categories:
flight of ideas
perseveration
loosening of associations
thought block

Disorders of the possession of thought include:
thought insertion
thought withdrawal
thought broadcasting



Many types of neurosis may be organised under three headings:
anxiety
obsessional disorder
somatoform (and dissociative) disorders

Neuroses are mental disorders without any demonstrable organic basis, in which the patient does not lose touch with external reality or experience psychotic symptoms. In general they represent exaggerated forms of the normal reactions to stressful events. Literally their name means a state of nerves.
Neuroses are characterised by:
the absence of symptoms such as hallucinations, delusions, thought disorder or intellectual impairment
anxiety is present
there is no change in personality
insight is preserved
Neuroses account for 20 to 25% of patients attending general practitioners