Review of DSM-5 Handbook of Differential Diagnosis

For the prospective reader considering reading this title from cover to cover

Thorough in its scope and excellent in its discussion, any prospective psychiatrist or medical student interested in learning in and out all the different diagnoses int he DSM-5 will find this book enlightening. The decision trees, which are usually the drier parts of medical books, are even helpful to peruse., but the latter half of the book that takes every diagnosis and compares it diagnosis by diagnosis is especially helpful. 

For those who have read this title and would like a discussion, please see below

One of my favorite discussions of the book was the differential based off substance use, which the book claims is one of the most common diagnostic errors made in clinical practice in psychiatry. Because of this, the book recommends one of your very first heuristics is trying to determine whether substance use is involved because of the ability for substances to mimic many other natural psychopathologies. Even taking a substance for a consistent period of time can have lingering effects in such disorders like Substance/Medication-Induced Major or Mild Neurocognitive Disorder, which I have never heard of before, but I think I have seen clinically while at the state hospital in Columbus where I saw firsthand how cocaine use can contribute to lingering cognitive challenges. I also had never heard of Hallucinogen-Persisting Perception Disorder, which the differential book talked about, which I will most certainly keep in mind in my own bundling diagnoses when I am considering why someone may be perceiving abnormal stimuli. Regarding the substances section, I thought it was insightful for the book to take a stance that substance use can be a form of self-medication for individuals who aren't able to access psychiatric care in the manner that they need and deserve. For example, only about 47% of those with mental illness received treatment in 2021.1

I like the discussion of how Psychiatric Disorder Due To A Medical Condition was phased out of the DSM-5-TR because of the implication of mind-body dualism with medical vs. psychological conditions being a distinction, which is anachronistic.2(p6) I agree with this because many parts about your general medical health influence your mental health (e.g., I tend to feel worlds different before and after an exercise routine). The current terminology is “general medical” etiology to denote that sometimes a psychiatric disorder can be caused by a medical condition classified outside the ICD-10 mental disorders chapter. Along with the discussion of care availability, I thought it was unique how the book’s sixth common step in psychiatric diagnosis—establishing a boundary with no mental disorder—talked about how the cultural context is very important in making a psychiatric diagnosis.2(p10) DSM-5-TR makes no attempt to define “clinically significant,” and I liked how the book talked about the availability of resources being a factor in determining whether or not a disorder is actually called such. In some ways, this gives power to the provider to make a clinical decision, but it also leaves ambiguity that can be disconcerting. I also liked the book's discussion that clinical judgment is needed when going through decision trees. Decision trees are very helpful, but as a learner I have found that they are oftentimes difficult to remember and can almost rely on too much Type 2 thinking (per Kahneman’s dualistic theory),3 clouding out the “larger picture” that might be obtained more readily in a pattern recognition manner. Looking up such a diagram is helpful in a relaxed setting, but, in an emergency scenario, not having such decision trees memorized would be problematic. I do wonder if, in the future, large language models can help find patterns and suggest very quickly to use certain decision trees at the bedside in a manner that does not encumber the physician. I think the future is exciting where human physicians can be enhanced by such tools. 

One of the most helpful parts of reading through and following the decision trees in the handbook was coming up with bundling diagnoses and important questions to ask. Rehearsing these mentally was a very beneficial process. When I encountered a diagnosis I did not recall, it was also helpful to have a copy of the DSM-5-TR nearby, where I could refresh my memory. It is helpful that in the DSM there is usually a differential diagnosis section with commentary. 

Throughout my time in this book, I was continually impressed by the complexity in certain types of presentations in psychiatry. One in particular is behavioral problems in a child. The differential diagnosis list is extensive, and from personal experience, having been on a child adolescent psychiatry rotation and dealing mainly with patients who can't provide information themselves and rely on their parents, the accurate etiology of such behavioral concerns is very challenging. Even speech disturbances have an incredible number of potential causes. Though, one criticism I have for the book is that Intermittent Explosive Disorder is not included on the decision tree2(p26) for behavioral problems. While on my CAP rotation, it was repeatedly emphasized that Intermittent Explosive Disorder is actually quite rare and usually occurs in a population who has comorbid Intellectual Developmental Disorder. However, it is still a potential and I wish they would have included it. 

One particular interesting insight from this book was how in almost all of the decision trees the very first two differentiators were whether the symptoms were due to the “physiologic effects of a substance” or of a “general medical condition.” I can particularly see how in a hospital these would be more common. This reinforced to me the importance of maintaining my medical school knowledge throughout my psychiatric career and working hard to make sure I'm "UpToDate" on all that I can be. I really enjoyed the discussion on the differential diagnosis of catatonia because there are a number of different etiologies you wouldn't normally consider, like catatonia associated with a manic episode in bipolar 1 disorder and medication-induced acute dystonia mimicking catatonia. On the decision tree for elevated or expansive mood, they had a typo in the decision tree for Gambling Disorder, but it was pretty self-explanatory that they meant otherwise. When the book was talking about how the cognitive impairment of Major Depressive episodes can mimic the severity of Major Neurocognitive Disorder, I immediately thought to a patient we had while I was on my third-year clerkship at Miami Valley, who had intractable depression, but whom we later realized on imaging had significant white matter disease (they mimic each other!). I thought the discussion around Stereotypic Movement Disorder2(p126) being on the differential of self-injurious behavior was interesting because I very specifically remember in Child Adolescent Psychiatry this year there was a patient who would very violently hit her head against her upper right forearm and this was quite distressing in the office while we were trying to gather information from her parents. I think that was a clear scenario where this Stereotypic Movement Disorder2(p126) diagnosis applied in the context of severe Autism Spectrum Disorder as well.

Below are several unique clinical pearls I took away from the section of 29 decision trees starting with a presenting symptom:

• Distractibility in children can be a reaction to an external stressor, so include that on your differential.2(p35)

• Have a patient talk at length about their delusion because oftentimes the specific details elicited by such help you determine its etiology on the differential.2(p38)

• The “with psychotic features” specifier can be added to Bipolar 1, Bipolar 2 Disorder, and Major Depressive Disorder, in order to clarify exactly what's going on.2(p44)

• The specifier “with behavioral disturbance” should be used if a patient is presenting with hallucinations secondary to a Major Or Mild Neurocognitive Disorder Due To Another Medical Condition.2(p44)

• In the context of a Conversion Disorder, one should not count pseudo-hallucinations as true hallucinations that require a diagnosis of a psychotic disorder to account for, as they tend to affect multiple sensory modalities at the same time with psychologically meaningful content.2(p44)

• Illusions involve misperceptions of sensory stimuli and are more suggestive of schizotypal personality disorder, delirium, or substance intoxication or withdrawal.2(p45)

• You don't technically need a depressive episode in Bipolar 1 Disorder, just the manic episode.2(p52)

• The advice to be very wary of diagnosing a manic episode surrounding times of gambling was helpful since the feelings when a person is winning can oftentimes resemble elevated and expansive mood. It also made the important distinction that those in a manic episode would have reckless behavior and could be more likely to gamble themselves. My takeaway: clearly elucidating the history is important in those living near Las Vegas 💸.2(p53)

• If the mood is primarily irritable, you need four and not just three criteria for manic episodes.2(p56)

• Cannabis 🌱intoxication can induce a depressed mood and is on the differential for such.2(p61)

• Waiting about one month after cessation of substance use is wise to see if the mood symptoms spontaneously resolve in patients, because substance/medication-induced depressive disorders do occur.

• If depression and mania are present at the same time, use the DSM-5 specifier manic episode with mixed features.

• A particularly dangerous combination for suicidal behavior is Major Depressive Disorder, Alcohol Use Disorder, and borderline personality disorder.2(p67)

• Suicidal Behavior Disorder is currently a condition undergoing further study but that there are no clinical instruments that yield enough positive predictive value.2(p71),4(p920)

• Since comorbid anxiety with major depressive episodes is so common, there is a specifier in Major Depressive Disorder with anxious features.2(p76)

• Taking a careful caffeine history is important with the decision tree for panic attacks because caffeine can be a covert culprit.2(p80)

• Adding the specifier “with panic attacks” onto other diagnoses like Specific Phobia, Separation Anxiety Disorder, or Obsessive Compulsive Disorder, for example, is appropriate when the cause of the panic is clearly elucidated.2(p82)

• When differentiating Panic Disorder from Agoraphobia, Agoraphobia involves multiple places where escape would be difficult, whereas Panic Disorder involves stimuli particularly likely to trigger additional attacks.2(p83)

• If there is a component of the fear of negative evaluation by others present since at least early adulthood, then consider avoidant personality disorder instead of Social Anxiety Disorder.2(p86)

• Even if a patient has another psychiatric disorder, if insomnia predominates, then you would still give a comorbid diagnosis of insomnia disorder.2(p100)

• Keeping Nightmare Disorder in the differential for PTSD and asking about whether or not dreams are particularly well-membered or extended in length is a good idea.2(p106)

• If sexual dysfunctions are insufficiently described or do not meet criteria because of infrequency for the patient, a diagnosis of Adjustment Disorder can be considered.2(p110)

• When considering someone who is displaying self-injury or self-mutilation, but is also confined in a hospital or children's home, remember that actually discharging them could be helpful since confined spaces can increase those behaviors.2(p126)

• More often than not, you should diagnose substance-induced disorders alongside substance use disorders.2(p129)

• If a patient is dysphoric after cocaine use, then cocaine withdrawal will likely suffice, whereas if they become suicidal, Cocaine-Induced Depressive Disorder may be more appropriate.2(p129)

• If substance use is combined with a general medical condition that is causing the clinical picture, consider Delirium Due To Multiple Etiologies as a diagnosis.2(p131)

• Lithium should be on the differential diagnosis for memory impairment.2(p137)

• Memory loss can appear in Post-Traumatic Stress Disorder as a type of avoidance, but it's usually associated with intrusion symptoms.2(p138)

• In order to diagnose delirium you need changes in attention and some change in cognition as well.2(p139)

• In Frontotemporal Dementia, oftentimes you can differentiate it from other causes by noticing that it spares learning, memory, and perceptual motor function.

• When differentiating Lewy Body Dementia and Parkinson's Disease, consider whether other symptoms of Parkinson's disease clearly precede the onset of the Neurocognitive Disorder. If the other way around, consider Lewy Body Dementia.2(p150)

The book then had a section on differential diagnosis by first examining what disorder is most likely and then provides contrasting information with other disorders. I thought this was a useful portion because premature closure with a diagnosis that seems to fit a patient and their story could be prevented by consulting such a resource and asking additional questions based off the differentiating factors. Below are the highlights and learning points I took away and found most meaningful from this section.

• One particularly good differential the book mentioned was between Autism Spectrum Disorder and Social Communication Disorder, where the latter involves an absence of restricted and repetitive behaviors that are seen in ASD.2(p166) 

• Along the lines of the previous point, Stereotypic Movement Disorder is very similar to Autism Spectrum Disorder, but does not involve social interaction and language developmental concerns.2(p167)

• Normal boredom should be on the differential with ADHD.2(p168)

• Specific Learning Disorder can mimic ADHD’s inattentive behavior because of frustration, but it's more limited to schoolwork as opposed to ADHD where multiple settings are involved.2(p169)

• Social inequality and poor academic performance due to lack of opportunity should be considered in patients who have Specific Learning Disorders because they might not have had the best teacher for reading, for example.2(p172)

• I imagine in the real world the correct diagnosis of ADHD would be rather difficult considering imperfect history and the complexity of children's behavior. Is it a Specific Learning Disorder? Are they just not paying attention? Are they not paying attention because it's not making sense in the first place?

• Myoclonus is differentiated from tics because tics have a premonitory urge and are less rapid than Myoclonus.2(p174)

• One can diagnose OCD even if they totally think their beliefs are true if you add the “with absent insight/delusional beliefs” qualifier.2(p179)

• Psychotic symptoms can occur in the context of personality disorders but usually only last 1 day or less.2(p180)

• Use the “with mixed features” specifier with MDD if there are manic or hypomanic symptoms that last shorter than the required time frame.2(p182)

• ADHD and Bipolar 2 Disorder’s hypomania may mimic each other, but it is important to remember that ADHD is present before age 12.2(p186)

• The dysphoric mood in bereavement is more around thoughts of the deceased as opposed to MDD which is generalized.2(p191)

• Premenstrual Dysphoric Disorder is a more extreme version (requires five total symptom categories) of Premenstrual Syndrome.2(p194)

• Irritability may be a common theme of depression in children,5 but if the irritability extends outside the depressive episodes then consider Disruptive Mood Dysregulation Disorder.2(p197)

• Social Anxiety Disorder and Separation Anxiety Disorder can look very similar to each other with the chief complaint of truancy, though following William Osler’s advice to hear the patient’s story will usually elucidate why they are trying to avoid. 

• Separation Anxiety Disorder is more focused on main attachment figures whereas dependent personality disorders involve a pervasive pattern among relationships.2(p199)

• Limited symptom attacks can be diagnosed when there are fewer than the required four symptoms needed for a panic attack (and you need two such unprovoked full-blown panic attacks to diagnose Panic Disorder, otherwise it is an isolated panic attack).2(p209)

• Specific Phobias can present similarly to OCD, but OCD uniquely had an involved obsession and compulsion that relieves the anxiety.2(p216)

• In a Major Depressive episode, low self-esteem may be present, but repetitive behaviors such as mirror checking or mental comparisons due to appearance concerns are not.2(p218)

• Histrionic Personality Disorder involves concern about one’s appearance but aren’t related to specific defects.2(p219)

• There is A Body Integrity Identity Disorder2(P219) characterized by the desire to have a limb amputated to correct a perceived mismatch.

• Persistent Complex Bereavement Disorder involves also having positive thoughts about the person in question whereas in PTSD the thoughts revolve around trauma experiences.2(p225)

• PTSD can have the “with dissociative symptoms” specifier, so differentiate PTSD from Dissociative Disorders in the DSM (e.g. Dissociative Identity Disorder, Dissociative Amnesia, Depersonalization/Derealization Disorder)

• A rape victim may not be able to recall portions of the traumatic event (dissociative symptoms of PTSD) but if they can’t remember the entire day, for example, this may be more Dissociative Amnesia.2(p230)

• Reality testing is intact (they know they are actually real) in those with Depersonalization/derealization disorder whereas in Psychotic Disorders they truly believe it.2(p232)

• Someone who gets angina whenever they are enraged could be diagnosed as having Psychological Factors Affecting Other Medical Condition.2(p241)

• Bulimia Nervosa and Anorexia Nervosa can both involve binge eating and purging, but anorexia also involves a low BMI (if BMI normalizes for 3 mos., then revert Dx back to Bulimia).2(p249)

• Binge-Eating Disorder is different from Bulimia Nervosa in that it doesn’t involve compensatory behaviors like vomiting at least weekly for three months.

• Insistence of someone with Gender Dysphoria that they are of the other gender is not considered a delusion that would be associated with a Psychotic Disorder.2(p261)

• A reluctance to confide in others in avoidant personality disorder should not be confused with paranoid personality disorder because there is a fear of embarrassment in the former that is less of a fear of exploitation in the latter.2(p275)

• Avoidant personality disorder involves an active desire for relationships (stifled by fear of negative perception) that schizoid personality disorder does not have. Social Anxiety Disorder may only involve a few situations and usually they have good relationships with their family, whereas avoidant personality disorder is more pervasive.

• Borderline personality behavior does not involve impulsivity and aggressiveness that is more characteristic of antisocial personality disorder.2(p279)

• In paranoid personality disorder, there may be antisocial behavior, but it is more motivated by revenge compared to those who have antisocial personality disorder and are more concerned with gain (from ignoring the basic rights of others).2(p280) 

• Dependent personality disorder lacks the flamboyant emotions of histrionic personality disorder.2(p282)

• A patient with OCPD believes perfection has not been achieved already, whereas someone with narcissistic personality disorder thinks it has been achieved.2(p286)

Those are a few of the biggest takeaways and things I thought were interesting from the book. I overall thought it was excellent, despite the reading in the latter half of the book being a bit dry at times. I do wish they had a direct comparison between social anxiety disorder and avoidant personality disorder which is a routinely misunderstood differentiation (the book largely separated the discussion of personality disorders off from the other disorders), but I think the read was rather comprehensive otherwise. Because of how well this book is written, I think I will try and pull out this title throughout my career when things are just not necessarily fitting one clinical picture and it's not as clear as I would like it to be.

References:

1. Key Substance Use and Mental Health Indicators in the United States: Results from the 2021 National Survey on Drug Use and Health. U.S. Department of Health and Human Services https://www.samhsa.gov/data/sites/default/files/reports/rpt39443/2021NSDUHNNR122322/2021NSDUHNNR122322.htm

2. Crocq MA, First MB. Dsm 5 Handbook Of Differential Diagnosis Spl Edition. First Edition. Cbs Publishing; 2005.

3. Kahneman D. Thinking, Fast and Slow. Macmillan; 2011.

4. Diagnostic and Statistical Manual of Mental Disorders: DSM-5-TR. American Psychiatric Association Publishing; 2022.

5. Leibenluft E. Irritability in children: what we know and what we need to learn. World Psychiatry. 2017;16(1):100-101. doi:10.1002/wps.20397