Dimensional

Integrating Dimensional Concepts
I t a Categorical
Into
C t
i l System
S t
Chao--Cheng Lin
Chao
Dep. Of Psychiatry, NTUH
2011/11/5
Outline
Categorical vs. Dimensional
Advantages of dimensional approach
Drawbacks of dimensional approach
Integration (Categorical & Dimensional)
Examples
Categorical vs.
vs Dimensional
Categorical
Binary
Relatively subjective
Rely on core symptoms
Dimensional
Ordinal/interval
Relativelyy objective
j
Nature of psychiatric
disorder
Dimension
• Superordinate: relevant to all disorders
• Supraordinate: relevant to one or several
(y
)
disorders (syndromatic)
• Cross-sectional
~ Shear 2007
Ad
Advantages
off di
dimensional
i l approachh
• Objective quantification & relatively
consistent
i
across patient,
i
clinicians,
li i i
& time
i
• Research: increase statistical p
power ,
decrease sample size
• Future:
F t
iincrease the
th likelihood
lik lih d off
discovering causal associations.
D b k off di
Drawbacks
dimensional
i l approachh
• Confusion about creating 2 diagnostic
systems
• Resistance to change
g
• Research needs vs. clinical utility
DSM-5
DSM
5
Dimensional
Categorical
Integration
Integration of categorical
& dimensional approaches
• Dimensional alternatives conform to
categorical
i l definitions
d fi i i
by
b workk groups.
• Necessity
y of categorical
g
distinctions for
clinical decision making & utility for
clinical communication & validity.
validity
• A clear, simple & consistent
correspondence between categorical &
dimensional approaches
pp
Integration of categorical
& dimensional approaches
• Define a dimensional scale for each
di
diagnosis
i by
b eg. item
i
response theory
h
• Creating
g a dimensional scale & relatingg
it back to a categorical definition by eg.
Receiver operating characteristics
• Mixed categorical-dimensional
approach
Examples
Core q
questions for adding
g
dimensional measures
• Which dimensions should be chosen?
Superordinate supraordinate
Superordinate,
supraordinate, cross
cross-sectional
sectional
• How many dimensions are feasible?
Selected diagnoses & criteria, all criteria?
• How complex & specific?
Uni- or multidimensional? Simple or complex?
• Psychometric issues
Established or new scales?
• For whom?
Targets
g for adding
g
dimensional measures
• Symptoms:
types of signs & symptoms,
symptoms syndrome
• Temperal/Time:
Age at onset, developmental, acuity, course,
duration,, outcome
• Etiology:
Di
Dispositional,
iti l neurobiological,
bi l i l trigger
ti
ett all
• Intensity/Frequency
y
q
y
A person-centered, model-based approach
to bridge dimensions & categories
• 15 dimensions (375-items) of Schedule for
Nonadaptive & Adaptive Personality (SNAP)
• Model-based cluster analysis.
A fo
fourr cl
cluster
ster solution
sol tion on 2 dimensions
Best fitting model
Best-fitting
model: Model 5 with
ith 7 cl
clusters
sters
Best fitting model with
Best-fitting
ith 7 cl
clusters
sters
Normal
Distresseddependent
Wild-oat
spreaders
d
Worker
bees
Severe
PD
Repressor
Rebels
Supraordinate dimensions for anxiety disorders
Future
• Whether dimensions should be created only
for major diagnoses or for some minimal
s bset of diagnoses
subset
• Varying needs of a diverse group of users
• Electronic tools
• Free-form
F
f
iinterview,
t i
semistructured
it t d
interview, structured interview, selfadministered questionnaire
Top-down
down vs
vs. bottom-up
bottom up approaches
• Top
C
Conclusion
l i
• Dimensional diagnosis is not seen as a
replacement for the categorical but rather as a
complementary
l
t
enhancement.
h
t
• Designers of DSM-5 have adopted a “mixedcategorical-dimensional” approach as a
guiding principle.
Thank you for attention
