CHAPTER 1: DIFFERENTIAL DIAGNOSIS STEP BY STEP
1) Ruling out Malingering and Factitious Disorder,
a. Two conditions in DSM-5 are characterized by feigning: Malingering and
Factitious Disorder. These two conditions are differentiated based on the
motivation for the deception. When the motivation is the achievement of a
clearly recognizable goal, the patient is considered to be Malingering.
When the deceptive behaviour is present even in the absence of obvious
external rewards, the diagnosis is Factitious Disorder.
2) Ruling out a substance etiology,
a. The first task is to determine whether the person has been using a
substance. This entails careful history taking and physical examination for
signs of Substance Intoxication or Substance Withdrawal.
b. Once substance use has been established, the next task is to determine
whether there is an etiological relationship between it and the psychiatric
symptomatology.
i. the psychiatric symptoms result from the direct effects of the
substance on the CNS
ii. the substance use is a consequence (or associated feature) of
having a primary psychiatric disorder (e.g., self-medication)
iii. the psychiatric symptoms and the substance use are independent
c. Is there a temporal relationship? What happens if the person quits taking
the substance? How much substance is taken and is this enough to cause a
disorder? What other factors could have been the cause?
3) Ruling out an etiological medical condition,
a. This differential diagnosis can be difficult for four reasons:
i. Symptoms of some psychiatric disorders and of many general
medical conditions can be identical;
ii. Sometimes the first presenting symptoms of a general medical
condition are psychiatric;
iii. The relationship between the general medical condition and the
psychiatric symptoms may be complicated;
iv. Patients are often seen in settings primarily geared for the
identification and treatment of mental disorders in which there
may be a lower expectation for, and familiarity with, the diagnosis
of medical conditions.
b. Once a general medical condition is established, the next task is to
determine its etiological relationship, if any, to the psychiatric
symptoms. There are five possible relationships:
i. The general medical condition causes the psychiatric symptoms
through a direct physiological effect on the brain;
1. The first clue involves the nature of the temporal relationship and requires
consideration of whether the psychiatric symptoms begin following the onset
, of the general medical condition, vary in severity with the severity of the
general medical condition, and disappear when the general medical condition
resolves;
2. The second clue that a general medical condition should be considered in the
differential diagnosis is if the psychiatric presentation is atypical in symptom
pattern, age at onset, or course.
ii. The general medical condition causes the psychiatric symptoms
through a psychological mechanism;
iii. Medication taken for the general medical condition causes the
psychiatric symptoms, in which case the diagnosis is a Medication-
Induced Mental Disorder;
iv. The psychiatric symptoms cause or adversely affect the general
medical condition;
v. The psychiatric symptoms and the general medical condition are
coincidental (e.g., hypertension and Schizophrenia). In the real
clinical world, however, several of these relationships may occur
simultaneously with a multifactorial etiology.
Finally, if you have determined that a general medical condition
is responsible for the psychiatric symptoms, you must determine
which of the DSM-5 Mental Disorders Due to Another Medical
Condition best describes the presentation.
4) Determining the specific primary disorder(s),
5) Differentiating Adjustment Disorder from the residual Other Specified and
Unspecified conditions,
a. If the clinical judgment is made that the symptoms have developed as a
maladaptive response to a psychosocial stressor, the diagnosis would be
an Adjustment Disorder. If it is judged that a stressor is not responsible
for the development of the clinically significant symptoms, then the
relevant Other Specified or Unspecified category may be diagnosed,
with the choice of the appropriate residual category depending on which
DSM-5 diagnostic grouping best covers the symptomatic presentation.
6) Establishing the boundary with no mental disorder.
There are six different ways in which two so-called comorbid conditions may be
related to one another:
1) Condition A may cause or predispose to condition B;
2) Condition B may cause or predispose to condition A;
3) An underlying condition C may cause or predispose to both conditions A and B;
4) Conditions A and B may, in fact, be part of a more complex unified syndrome that
has been artificially split in the diagnostic system;
5) The relationship between conditions A and B may be artifactually enhanced by
definitional overlap;
6) The comorbidity is the result of a chance co-occurrence that may be particularly
likely for those conditions that have high base rates.
, DSM-5 CRITERIA
SCHIZOFRENIESPECTRUM- EN ANDERE
PSYCHOTISCHE STOORNISSEN
Waanstoornis, critA:
A) De aanwezigheid van één (of meer) wanen, met een duur van één maand of langer.
Kortdurende psychotische stoornis, critA:
A) Aanwezigheid van een (of meer) van de volgende symptomen. Minstens één daarvan
moet (1), (2), of (3) zijn:
1) Wanen;
2) Hallucinaties;
3) Gedesorganiseerd spreken (bijv. frequente ontsporing of incoherentie);
4) Ernstig gedesorganiseerd of katatoon gedrag.
Schizofreniforme stoornis, critA:
A) Twee (of meer) van de volgende kenmerken waarvan elk een significant deel van de
tijd gedurende een periode van één maand aanwezig is (of minder, indien succesvol
behandeld). Minstens één daarvan moet (1), (2), of (3) zijn:
1) Wanen;
2) Hallucinaties;
3) Gedesorganiseerd spreken (bijv. frequente ontsporing of incoherentie);
4) Ernstig gedesorganiseerd of katatoon gedrag;
5) Negatieve symptomen (zoals verminderde emotionele
expressie/initiatiefverlies).
B) Episode duurt minstens 1 maand, korter dan 6 maanden
Schizofrenie, critA+B:
A) Twee (of meer) van de volgende kenmerken, waarvan elk in een periode van één
maand een significant deel van de tijd aanwezig is (of korter indien succesvol
behandeld). Minstens één van deze moet (1), (2), of (3) zijn:
1) Wanen;
2) Hallucinaties;
3) Gedesorganiseerd spreken (bijv. frequente ontsporing of incoherentie);
4) Ernstig gedesorganiseerd of katatoon gedrag;
5) Negatieve symptomen (zoals verminderde emotionele
expressie/initiatiefverlies).
B) Voor een significant deel van de tijd sinds het begin van de stoornis ligt het niveau
van functioneren op een of meer belangrijke levensgebieden, zoals werk,
interpersoonlijke relaties of zelfverzorging, duidelijk onder het niveau van voor het
begin van de stoornis (of, als het begin tijdens de kinderjaren of adolescentie ligt, het is
niet gelukt om het verwachte niveau van functioneren op interpersoonlijk gebied, op
school en in de studie, en beroepsmatig te bereiken).
