Diagnostic hierarchy, need to exclude before considering next category, starting with organic in all cases:
Organic Disorders e.g. space occupying lesion.
Psychotic Disorders e.g. schizophrenia.
Mood Disorders e.g. bipolar affective disorder.
Neurotic Disorders e.g. agoraphobia, OCD.
Personality Disorders e.g. borderline personality disorder.
A table can be used to structure thinking in terms of time and nature of triggers when considering causation. (see the 3x3 table below. This table can also be used when considering the FORMULATION (see next page)