Differential Diagnosis

Question 1

What are the 6 steps of DSM-5 differential diagnosis?

Answer 1

1) Rule out Malingering and Factitious Disorder
2) Rule out Substance Etiology (Including Drugs of Abuse, Medications)
3) Rule out a Disorder Due to a General Medical Condition
4) Determine the specific primary disorder(s)
5) Differentiate Adjustment Disorders from the residual Other Specified or Unspecified conditions
6) Establish the boundary with no mental disorder

Question 2

What is Step 1 and why is it important?

Answer 2

Rule out Malingering & Factitious Disorder (when patients deceive the clinician by producing or feigning the presenting symptoms)
- cus if the patient is not being honest regarding then ature/severity of their symptoms then diagnosis accuracy is threatened

Question 3

What is the difference between Malingering and Factitious Disorder?

Answer 3

differentiated based on motivation for the deception
- when motivation is the achievement of a clearly recognisable goal (insurance compensation, avoiding legal/military responsibilities, obtaining drugs etc) -> patient is Malingering
- when deceptive behaviour is present even in absence of obvious external rewards, the diagnosis is Factitious Disorder

Question 4

When should a clinician be suspicious when doing the first step of differential diagnosis (seeing if theres factitious/malingering)? 5 situations

Answer 4

1) when there are clear external incentives to the patients being diagnosed w a psychiatric condition (prison/crime settings, disability benefits)
2) when the patient presents w a cluster of psychiatric symptoms that conforms more to a lay perception of mental illness rather than to a recognised clinical entity
3) when the nature of the symptoms shifts radically from one clinical encounter to another
4) when the patient has a presentation that mimics a role model (another patient on the unit, a mentally ill family member)
5) when the patient is characteristically manipulative or suggestible
-> these criteria exist cus you shouldnt treat patients as hostile witnesses & be too skepticial, but not too gullible either

Question 5

What is Step 2 in the differential diagnosis?Why is it hard?

Answer 5

Rule out substance etiology: (including meds): do the presenting symptoms arise from a substance that is exerting a direct effect on the CNS?
difficult because even if substance use & psychopathology occur together does not mean theres a cause-effect relationship

Question 6

what are the substeps of ruling out substance etiology in differential diagnosis?

Answer 6

1. determine whether a person has been using a substance (history taking & physical examination for intoxication/withdrawal symptoms, but also family member consultation & lab analysis of body fluids since ppl often underestimate their own intake)
2. if established, then next step is determining whether there is an etiological relationship between it & the psychopathology (3 possible relationships) does the substance cause the symptoms

Question 7

what are the 3 possible relationships between substance use & psychopathology?

Answer 7

• symptoms result from the direct effects of the substance on the CNS (resulting in diagnosis of substance induced disorders in DSM) aka causal relationship
• substance use is a consequence (or associated feature) of having a primary psychiatric disorder (eg self medication)
• the psychiatric symptoms & substance use are independent (can start to interact later on; likely when one has occured w/o the other)

Question 8

when is a causal relationship from substance to symptoms likely?

Answer 8

• theres a close temporal relationship between use & symptoms (a) if symptoms only occured w/ substance, b) if symptoms remit within 1m (flexible) of cessation of use)
• theres high likelihood that the used substance can result in presenting symptoms (consider nature, amount & duration of use)
• there are no better alternative explanations

Question 9

how do you determine whether there is an alternative explanation for the symptoms to be occuring, other than substance use?

Answer 9

• take history of similar episodes unrelated to substance
• take fam history of the primary disorder
• ask about physical exam or labfindings that suggest medical condition

Question 10

why is determining a close temporal relationship between substance use & symptoms hard?

Answer 10

• some ppl arent reliable historians
• often symptoms & substance use can start at same time and be chronic from then onwards (then u look at what happens when sober in rehab)

Question 11

when is a causal relationship from symptoms to substance use likely?

Answer 11

when psych symptoms occur first and/or exist at sober times
but accuracy of retrospective reporting may be limited so use other informants or review past records

Question 12

when is an independent relationship between substance use & symptoms likely?

Answer 12

if one has occured w/o the other
but might still interact later on when initially independent (complicate each other, have same underlying factor…)

Question 13

What do u do once its determined that substance causes the symptoms?

Answer 13

decide which substance induced MD best fits

Question 14

What is Step 3 of differential diagnosis?

Answer 14

Rule out a disorder due to a general medical condition

Question 15

what does “organic rule out” refer to?

Answer 15

step 2 & 3 in differential diagnosis, cus its ruling out “physical causes” of the symptoms

Question 16

why is step 3 of differential diagnosis so difficult?

Answer 16

1. symptoms of some psych conditoins & of many general medical conditions can be identical (IN OTHER WORDS virtually any psych presentation can be caused by the direct physio effects of a medical condition)
2. the first symptoms of a med condition can be psych
3. relationship between med condition & psych symptoms may be difficult
4. patients often seen in psych focused environments where less is known about med

Question 17

what are the substeps of step 3?

Answer 17

take direct history, lab tests & physical exam of most likely med condition. If med condition etablished, determine its etiological relationship (if any) to the psych symptoms: 5 options
1. med condition causes the psych symptoms through direct physio effect on brain (see indicators of this step) SO MD DUE TO AMD ESTABLISHED
2. med condition causes the psych symptoms through psych mechanism (MDD in response to cancer diagnosis)
3. meds taken for the med condition cause the psych symptoms (see step 2 of DD)
4. psych symptoms cause/affect the med condition (indicate Psych Factors affecting other MC)
5. psych symptoms & med condition are coincidental

Question 18

what are the 2 clues that psych symptoms are caused by direct physio effect of MC

Answer 18

1. nature of temporal relationship (a) if psych symptoms begin following onset of med condition, b) vary in severity w the severity of the med condition, & c) dissapear when condition resolves -> if all yes then likely that condition leads to psych symptoms, (though not always)
2. if the psych presentation is atypical in symptom pattern age at onset, or course
   IF U ESTABLISH DIRECT EFFECT THEN DETERMINE WHICH MD DUE TO AMD FITS BEST

Question 19

What is step 4 of DD?

Answer 19

determine the specific primary disorder (what fits best)

Question 20

What is step 5 of DD?

Answer 20

Differentiate Adjustment Disorders From the Residual Other Specified or Unspecified Disorders.
if theres clinically significant impairment, distress, & represent bio/psych dysfunction but dont fit a specific DSM diagnosis, can still diagnose:
- adjustment disorder: symptoms result from a maladadaptive response to a psychosocial stressor
- If a stressor is not responsible for symptoms, Other Specified (specifies reasons why the presentation doesnt meet specific criteria) or Unspecified categories (doesnt give specific reasons) may be diagnosed based on the DSM-5 grouping that best covers the presentation.

Question 21

What is step 6 of DD?

Answer 21

Establish boundary with no mental disorder

Whether it’s clinically significant distress/impairment (your judgment; individual seeking help makes it clinically significant, comorbid psych presentations requiring clinical attention also clinically signification)
some conditions arent full disorder due to lacking internal dysfunction (diagnosed in section 2 of dsm)