eiko fried university of leuven, belgium 1 the differential impact of individual depression symptoms...
DESCRIPTION
Depression symptoms DSM-5 MDD diagnosis: 1.Diminished interest or pleasure 2.Depressed mood 3.Increase or decrease in either weight or appetite 4.Insomnia or hypersomnia 5.Psychomotor agitation or retardation 6.Fatigue or loss of energy 7.Worthlessness or inapproriate guilt 8.Problems concentrating or making decisions 9.Thoughts of death or suicidal ideation 3IntroductionTRANSCRIPT
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Eiko FriedUniversity of Leuven, Belgium
"The differential impact of individual depression symptoms on impairment of
psychosocial functioning"
Introduction 2
Major Depressive Disorder (MDD)
• Prevalent (Kessler et al., 2003)
• Recurrent(McClintock et al., 2010)
• Costly(Lopez et al., 2006)
Introduction 3
Depression symptoms
• DSM-5 MDD diagnosis:1. Diminished interest or pleasure2. Depressed mood3. Increase or decrease in either weight or appetite4. Insomnia or hypersomnia5. Psychomotor agitation or retardation6. Fatigue or loss of energy7. Worthlessness or inapproriate guilt8. Problems concentrating or making decisions9. Thoughts of death or suicidal ideation
Introduction 4
Depression symptoms
• DSM-5 MDD diagnosis:1. Diminished interest or pleasure2. Depressed mood3. Increase or decrease in either weight or appetite4. Insomnia or hypersomnia5. Psychomotor agitation or retardation6. Fatigue or loss of energy7. Worthlessness or inapproriate guilt8. Problems concentrating or making decisions9. Thoughts of death or suicidal ideation
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Introduction 5
Disease model
Introduction 6
Disease model
• Depression is a latent disorder
D
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s2
s3
s4
s5
Introduction 7
Disease model
• Depression is a latent disorder• Depression is the common cause of its symptoms
s1
s2
s3
s4
s5
D
Introduction 8
Disease model
• Depression is a latent disorder• Depression is the common cause of its symptoms• Measure MDD symptoms and use them to indicate
presence of depression
s1
s2
s3
s4
s5
D
Introduction 9
Disease model
Consequences:• Symptoms are passive indicators• Symptoms are interchangeable: irrelevant what
particular symptoms a person has (DSM: 5/9)– Symptom number, not symptom nature matters
• This disease model justifies adding up symptoms to sum-scores
s1
s2
s3
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s5
D
Introduction 10
Disease model
• Common-cause model implausible considering the pronounced symptomatic variability among MDD patients > 1500 unique symptom profiles qualifying for DSM-5 MDD diagnosis
• Alternative: understand symptoms as distinct entities worth studying individually
• Prior research: symptoms differ from each other in important aspects– Symptoms have different risk factors
(Fried et al., 2013)– Symptoms differ in their genetic background
(Kendler et al., 2013; Myung et al., 2012)– Symptoms and their impact on impairment psychosocial functioning
(Fried & Nesse, 2014)
STAR*D: impaired functioning 11
Depression & impairment
• Majority of MDD patients: moderate to severe impairment (Kessler et al., 2003)
• Impairment long-lasting and affects various domains of living (e.g., home, workplace, friendships) (Hays et al., 1995; Hirschfeld et al., 2002)
• Unknown whether individual symptoms differ in their impact on impairment
STAR*D: impaired functioning 12
Methods
• NIMH dataset: "Sequenced Treatment Alternatives to Relieve Depression" (STAR*D)
• Enrollment stage: 3,703 MDD outpatients– Cross-sectional– Age M ~ 41, ~ 60% female– No antidepressants
• Goal: test the impact of MDD symptoms on impairment– Depression symptoms (QIDS-16) (e.g., insomnia & hypersomnia)– Psychosocial impairment (WSAS); example question: "Because of my
depression, my ability to work is impaired"
STAR*D: impaired functioning 13
Question 1
• Do symptoms have differential effects on impairment?
H1 - heterogeneity model:IMPAIRMENT ~ S1 + S2 + S3 ... AGE + SEX
vs.
H0 - homogeneity model:IMPAIRMENT ~ S1 + S2 + S3 ... AGE + SEX
differential impact
equal impact
STAR*D: impaired functioning 14
Question 1
H1 - heterogeneity model:IMPAIRMENT ~ S1 + S2 + S3 ... AGE + SEX
H0 - homogeneity model:IMPAIRMENT ~ S1 + S2 + S3 ... AGE + SEX
²diff = 394.5, dfdiff = 13p < 0.001R² = 41%
• Do symptoms have differential effects on impairment?– Yes.
STAR*D: impaired functioning 15
Question 2
• How much variance of impairment does each individual symptom explain?
• Relative importance analysis
Impairment, total variance = 100%
STAR*D: impaired functioning 16
Question 2
• How much variance of impairment does each individual symptom explain?
• Relative importance analysis
Impairment, total variance = 100% Variance explained by symptomsR² = 41%
STAR*D: impaired functioning 17
Question 2
• How much variance of impairment does each individual symptom explain?
• Relative importance analysis100%
S120%
S210%
S440%
S330%
Impairment, total variance = 100%
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• Symptoms vary dramatically in their explained variance of impairment
• Coefficients within compound symptoms differ from each other– Slowed vs. agitated
p < 0.05
<
<
STAR*D: impaired functioning 19
Question 3
• Do symptoms vary in their associations across 5 impairment subdomains?– work, home, social activities, private activities, close relationships– Yes– ²diff = 299.8 (dfdiff = 56); p < 0.001
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D1: work; D2: home; D3: social act.; D4: private act.; D5: relationships
fatigue
interest loss
STAR*D: impaired functioning 23
Conclusions
• Some depression symptoms are much more impairing than others– Two MDD patients with similar symptom sum-scores potentially suffer
from different levels of impairment• Analyses of individual symptoms reveal important clinical
information that are obfuscated by analyses of sum-scores
STAR*D: impaired functioning 24
Implications
• Main problems of modern psychiatry– Antidepressants only marginally efficacious compared to placebos
(Kirsch et al., 2008; Pigott et al., 2010; Turner et al., 2008)
– "Questionable" reliability of MDD diagnosis in DSM-5 field trials (Regier et al., 2013)
– In the largest GWAS study with > 34,000 subjects, no single locus was significantly associated with depression diagnosis (Hek et al., 2013; see also: Lewis et al., 2010; Shi et al., 2011; Wray et al., 2012)
• Current psychiatric research and practice lumps individuals suffering from a wide range of disparate symptoms into one undifferentiated category, obfuscating dramatic differences between patients diagnosed with MDD.
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