what is nosology?
The study of how medicine classifies illnesses
Nosology classification methods
Symptom-based classification - two key issues that represent a challenge to this approach
two key issues that represent a challenge to this approach to classification include:
1. symptom overlap
2. heterogeneity
What is Symptom Overlap?
some symptoms (like anhedonia) are common to many mental illness (like schizophrenia, MDD) - some are especially common (anxiety/tension)
What is heterogeneity?
Individuals with the same diagnosis may display very different symptoms and present differently (wide variety of symptoms for each disorder)
Implications of symptom-based classification
OCD and PTSD are both similar and different
What is OCD?
OCD can be described as a manifestation of anxiety revolving around obsessive and intrusive thoughts
- widely misunderstood, partially due to media depictions
Two primary components:
1. Obsessions: disruptive, anxiety producing thoughts and/or mental images - uncontrollable thoughts - common themes related to contamination, sex, religion, precision violence, harm
2. Compulsions: repetitive actions or thoughts which are performed in order to help relieve anxieties stemming from obsessions - these could be repetitive cleaning, counting, checking on things
- when severe, can prevent individuals from completing normal routines, and can result in serious impairment
7 types of obsessions + misc
6 compulsions + misc
OCD prevalence and tendencies
What is PTSD?
Similar to OCD due to the intense sensations of anxiety and tension (but not the same at all)
- typically arises following a single traumatic event or repeated trauma over a period of weeks, months, or years (diverse route to emergence)
- these events involve experiencing or witnessing severe harm, injury, danger, or death
- symptoms brought on by trauma, including second-hand experience of trauma (a loved one experiencing trauma)
- we are familiar with combat-related PTSD, but accidents, abuse, and violent crime can also trigger PTSD (a wider range of experiences are now understood to be traumatic)
PTSD Symptoms
Similarities between OCD and PTSD
Differences between OCD and PTSD
Somatic Symptom and Illness Anxiety Disorder
Somatic Symptom Disorder: describes individuals who have anxiety and/or a fixation on somatic symptoms such as headache and pain
- was previously “conversion disorder” (distress or internal conflict “converted” into physical dysfunction) before that “hysteria”
- people may or may not have a diagnosis for a physical illness that is causing their symptoms
- the diagnosis of this disorder is related to an “excessive and abnormal” psychological reaction to the physical symptoms
Illness Anxiety Disorder: this disorder is characterised by excessive worry about the possibility of becoming ill, previously known as hypochondriasis
- “easily alarmed about personal health status” may perform excessive health-related behaviours (checking for signs of illness)
- may extensively use health system, but concerns are rarely alleviated through care/visits, often feel medical assessments has been inadequate
- may be extra-sensitive to bodily sensations, including more likely to report side effects of medications
Clinical Perspectives (positivist and constructivist)
Study of assumptions about knowledge are often based on two broad frameworks:
Epistemology
The study or a theory of the nature and grounds of knowledge especially with reference to its limits and validity
Positivism
Positivism –> Post-positivism
Post-Positivism
constructivism
Positivism and Constructivism’s view in relation to mental health
in the field of mental health:
- the constructivist or contingent nature of knowledge is evident in the evolving nature of diagnostic criteria and definitions of mental disorders in each new version of the DSm (disorders removed or redefined, new ones added, criteria revised)
This highlights how scientific understanding and medicine is not truly an objective “truth” but rather an evolving cultural system of knowledge
Sex differences in OCD
males more affected in childhood
females slightly more affected in adulthood