journal club: telomere length and cortisol reactivity in children of depressed mothers

Telomere Length And Cortisol Reactivity In Children Of Depressed Mothers

IH GotlibJ LeMoultNL ColichLC Foland-RossJ HallmayerJ JoormannJ LinOM Wolkowitz

Molecular Psychiatry advance online publication, 30 September 2014; doi:10.1038/mp.2014.119

1

Overview• Introduction

• Telomeres • HPA-Axis derangement in Major Depressive Disorder (MDD)

• Related studies

• ArticleAimMaterial and MethodsResultsDiscussionLimitations 2

Molecular Psychiatry • “Molecular Psychiatry publishes work aimed at elucidating biological

mechanisms underlying psychiatric disorders and their treatment. The emphasis is on studies at the interface of pre-clinical and clinical research, including studies at the cellular, molecular, integrative, clinical, imaging and psychopharmacology levels”

• Impact Factor: 15.147*

• Rank:1/135 Psychiatry5/251 Neuroscience4/291 Biochemistry & Molecular Biology

• *2013 Journal Citation Report (Thomson Reuters, 2014)

3

Introduction - Telomeres

• Regions of repetitive nucleotide sequences at each end of a chromatid

• Vertebrates – TTAGGG1. Prevent chromosomes from losing base-pair sequences at their ends 2. Prevent chromosomes from fusing / oxidative stress

• Disposable buffers at the ends of chromatids – Truncated during cell division – Protect the genes before them on the chromatids from being truncated

instead

The 2009 Nobel Prize in Physiology or Medicine - Press Release

4

5

6

7

8

Introduction – HPA Axis Dysregulation in MDD

9

Introduction – HPA Axis Dysregulation in MDD• CRH & corticosteroid levels

remain elevated • NE, 5-HT, DA and GABA

levels decrease

• HYPERCORTISOLEMIA • ↓ inhibitory 5-HT tone • ↑ drive from NE, ACh or CRH • ↓ feedback inhibition from

Hippocampus

• Comprehensive Textbook of Psychiatry, 9th Ed Kaplan & Sadock

10

Related studies - 1Leukocyte Telomere Length in Major Depression:

Correlations with Chronicity, Inflammation and Oxidative Stress - Preliminary Findings

AIM : To determine if1. Leucocyte telomeres are shortened in Major Depressive Disorder

(MDD) 2. Whether this is a function of lifetime depression exposure 3. Whether this is related to putative mediators, oxidation &

inflammation • METHOD

– Leucocyte telomere length compared in 18 unmedicated MDD subjects & 17 controls

– Correlated with Lifetime depression chronicity, peripheral markers of oxidation & inflammation

• Wolkowitz OM, et al. (2011) Leukocyte Telomere Length in Major Depression: Correlations with Chronicity, Inflammation and Oxidative Stress - Preliminary Findings. PLoS ONE 6(3): e17837. doi:10.1371/journal.pone.001783711

Related studies - 1 (contd…)• Results

– Depressed group (as a whole) did not differ from controls in telomere length

– Telomere length was significantly inversely correlated with lifetime depression exposure (even after age control) p<0.05

• Avg telomere length in depressed subjects above median of lifetime depression exposure was 281 BPs shorter than controls ≈ 07yrs of accelerated cell aging

• Conclusion – Indication that accelerated aging at cellular level is proportional to

lifetime exposure to MDD – Suggests that telomere shortening does not antedate depression

• Telomere shortening may progress in proportion to lifetime depression exposure

12

Related studies - 2Major depressive disorder and accelerated cellular aging :

results from a large psychiatric cohort study

• AIM : To determine whether1. MDD is associated with accelerated biological aging 2. Depression characteristics (severity, duration, medication) further

impact biological aging

• METHOD– TL assessed using Telomere sequence copy number (T) compared

to single-copy gene copy number (S) using quantitative PCR • 1095 current MDD patients • 802 remitted MDD patients • 510 Control subjects

• JE Verhoeven Molecular Psychiatry advance online publication, 12 November 2013; doi:10.1038/mp.2013.15113

Related studies - 2 (contd…)

• Results– Compared with control subjects (mean bp=5541)

• TL was shorter in remitted MDD patients (mean bp=5459, p=0.014)• TL was shorter in current MDD patients (mean bp=5461, p=0.012)

– Within current MDD patients, shorter TL was associated with both • Higher depression severity (p<0.01) • Longer symptom duration in the past 04 years (p=0.01)

• Conclusion – Depressed patients show accelerated cellular aging according to a

dose-dependent gradient – Exposure to depression leaves an imprint

• Remitted MDD patients had shorter TL than control

14

Related studies - 3The Association of Major Depression, Conduct Disorder, and Maternal Overcontrol with a Failure to Show a Cortisol Buffered Response in 4-

Month-Old Infants of Teenage Mothers

• AIM : To explore whether MD (lifetime, during pregnancy, postpartum), CD, and maternal over-control are associated with increased cortisol reactivity in 4-month-old infants of teenage mothers

• METHOD– Between 2 and 4 months, a normal shift occurs in the

adrenocortical system • marked decrease in infant cortisol response when facing mild stressors

– Using arm restraint as a stressor, morning salivary cortisol was taken pre-stressor and post-stressor in 212 infants

• R. Azar et al.The Association of Major Depression, Conduct Disorder, and Maternal Overcontrol with a Failure to Show a Cortisol Buffered Response in 4-Month-Old Infants of Teenage Mothers Biol Psychiatry 2007;62:573–579 15

Related studies - 3 (contd…)• Results

– Independent of the predictors, there was no cortisol response to arm restraint in 4-month-old infants

– Cortisol of infants whose mother had a lifetime history of MD significantly increased from t1 to t2 [from .20 to .29 μg/dL, p< .01]

– Infant cortisol was NOT related to • MD Severity/ Depression during pregnancy / Post-partum depression

• Conclusion – Lower baseline levels of cortisol (T1) in infants of mothers with history of

MD may partly explain their increased post-stressor cortisol measure– Finding on lifetime MD may indicate a biological risk for stress reactivity– Possible that it is not history of MD that is linked to stress reactivity but

rather other associated factors like prenatal stress or anxiety

16

Related studies - 4Reduced telomerase activity in human T lymphocytes

exposed to cortisol

• AIM : To determine whether cortisol might affect telomerase activity in immune cells

• METHOD– Cellular telomerase activity measured using the Telomeric repeat

amplification protocol (TRAP) assay• Results expressed as “Total Product Generated”, TPG, which reflects the

telomerase activity in the sample• Calculated according to a computer program which integrates signal

intensity over the telomere length distribution on the gel as a function of molecular weight

• Choi J et al. Reduced telomerase activity in human T lymphocytes exposed to cortisol. Brain Behav Immun 2008; 22: 600–605.

17

Related studies - 4 (contd…)• Results

– Exposure of human T lymphocytes to cortisol associated with a significant reduction in telomerase activity both during primary stimulation of resting cells and secondary stimulation of previously activated cells.

• The effect is observe in both CD4 and CD8 T

– Hydrocortisone in physiological ranges of cortisol had no effect on the telomerase activity

– Higher concentrations of hydrocortisone, comparable to those that might be reached in vivo during stress, reduced telomerase activity by as much as 50%.

• Conclusion – Findings provide a potential mechanism for stress-associated

telomere length attrition

18

1. Telomere shortening α dose dependent lifetime depression exposure

2. Persons at risk for depression manifest HPA-axis dysregulation (exaggerated activation to stress)

3. Telomere shortening is assoc with low Telomerase activity, which may be seen on exposure to high levels of cortisol

19

Telomere Length And Cortisol Reactivity In Children Of Depressed Mothers

• IH Gotlib• J LeMoult• NL Colich• LC Foland-Ross• J Hallmayer1• J Joormann• J Lin• OM Wolkowitz

• Molecular Psychiatry advance online publication, 30 September 2014; doi:10.1038/mp.2014.119 20

IntroductionAIM

To assess telomere length in individuals who are at high risk of developing MDD but who have not yet experienced a depressive episode

• Shortened telomere length is a pre-existing condition or risk factor for developing MDD

vs • Shortened telomere length is a response to or

concomitant of major depressive episodes 21

Materials & methods – Subjects & Clinical Assessment

• 97 girls aged 10-14yrs with no current or past Axis 1 dx – 47 = mothers with no current or past Axis 1 dx (CTL)– 50 = mothers with h/o recurrent depressive episodes during

daughter’s lifetime (RSK)

• Daughters administered Kiddie Schedule for Affective Disorders and Schizophrenia (KSADS-PL) – assesses current and past episodes of psychopathology in children

and adolescents according to DSM-III-R and DSM-IV criteria– Interviews of parent(s) & child– Final summary ratings which include all sources of information

(parent, child, school, chart, and other)

22

Materials & methods – Subjects & Clinical Assessment• Mothers administered SCID-IV

– Recurrent episodes of MDD incl in RSK – Absence of current or past Axis 1 dx in CTL grp

• Random evaluation of 10% of SCID-IV & KSADS interviews by independent rater blind to group membership

• In all cases diagnoses of the following matched original interviewer’s diagnosis (k=1)– Recurrent Depressive Episodes in RSK mothers – Absence of Axis 1 disorder in CTL mothers – Absence of Axis 1 disorder in daughters

• Eligible daughters also completed – 10-item version of Children’s Depression Inventory – Pubertal status via Tanner Staging

23

Materials & methods – Telomere Assessment • Genomic DNA purified from 500μl of saliva • Telomere length commonly assessed in leucocytes

– Significant positive correlation (0.72, p=0.002) between leucocyte telomere length and telomere length measured in saliva

For each sample of DNA determine the

factor by which the sample differs from

a reference DNA sample in its

Ratio of Telomere copy number to Single copy gene copy

number (T:S)

Telomere Repeats in each sample

The level of dilution of a reference DNA sample

that would make the experimental and

reference samples equivalent WRT

the number of PCR cycles needed to generate a given amount of

telomere PCR product during

exponential phase of PCR amplification

Single copy gene in each sample

The level of dilution of a reference DNA sample

that would make the experimental and

reference samples equivalent WRT

the number of PCR cycles needed to generate a given amount of

single copy gene PCR product during

exponential phase of PCR amplification

25

Materials & methods – Stress Task

26

• 30mins Rest period • Part 1 – 3mins serial subtraction task (reverse serial 7 starting @ 400) • Part 2 – 12mins Ewart Social Competence Interview

– 6 cards detailing stressor categories (school, work, family, friends, money, neighborhood) and common subjects given by peers

– Determined why stressful– Reconstruct a particular situation & probe – Imagine hypothetical solution

• Neutral video

• Saliva samples imdtly before and at 15, 30 and 45mins after onset – Peak cortisol response 21-40mins after onset of stressor – Cortisol recovery to baseline 41-60mins after onset of stressor

Results• Participant Characteristics

– RSK and CTL groups did not differ wrt age, ethnicity or Tanner stage (all p>0.05)

– RSK group had slightly but significantly higher scores on CDI than CTL group BUT scores of both groups were well below clinical cutoff of 8

– Both within groups and across groups, Telomere length was not significantly correlated with age, Tanner Stage or CDI scores

27

Results - Telomere Length

• Girls in RSK group had significantly shorter telomeres than girls in the CTL group (M=1.524T/S vs 1.754T/S, p=0.001)

• Results did not significantly change when age, Tanner stage and CDI were included as covariates

28

Results – Cortisol Response to Stress • Baseline cortisol levels did

not differ significantly as a function of telomere length, risk group or their interaction

• Indls with shorter telomeres exhibited significantly greater cortisol reactivity to stress

• No main effect of risk group on reactivity

• Cortisol recovery was not affected by TL, risk group, their interaction 29

Results

1. Telomere length was not significantly correlated with age, Tanner stage or CDI scores

2. Girls in the RSK group had significantly shorter telomeres than girls in the CTL group

3. Girls with shorter telomeres exhibited significantly greater cortisol reactivity to stress in both RSK and CTL

4. Cortisol recovery from stress was not affected by telomere length, risk group or their interaction

30

Discussion • Healthy children at familial risk for depression have shorter

telomeres than their non-risk peers – Hence telomere shortening seems to be antecedent to and

potentially a risk factor for onset of depression

• Genetic v/s Environmental – Why has shortening taken place? – Genetic

• Operationalized risk based on h/o recurrent depressive episodes in mother

– Environmental • All girls stayed with mothers • Maternal depression is assoc with a stressful early environment for

children Lovejoy MC, Graczyk PA, O’Hare E, Neuman G. Maternal depression and parenting behavior: a meta-analytic review. Clin Psychol Rev 2000; 20: 561–592. 31

Discussion

• Nature of the assocn betn TL and cortisol secretion still unclear – Cortisol inhibits telomerase in vitro – Telomere shortening is a precursor to depression ,

condition char by HPA Axis deregulation • ? Possible a 3rd variable may be responsible for

both

32

Discussion

• Telomere shortening is not only a marker of stress, but also a mechanism of biological aging

• Medical illnesses observed most frequently in indls with psychiatric conditions are those most commonly seen with advanced age (e.g. Cardiovascular Dx, stroke, dementia)

• Blackburn EH. Telomere states and cell fates. Nature 2000; 408: 53–56.• Evans DL et al. Mood disorders in the medically ill: scientific review and recommendations. Biol Psychiatry 2005; 58:

175–189.

• Possibility that psychiatric illnesses are associated with accelerated aging at cellular/organismic level

33

Limitations

1. Narrow age range of participants (10-14yrs)– Cannot examine whether findings extend to a broader

age range of indls at risk for depression

2. Girls in RSK grp had slightly but significantly higher CDI scores

3. Superficial nature of Tanner staging as a measure of pubertal status

34

Limitations

• Numerous confounders are completely ignored – Life events, Socio-economic status

• Repetitive

35

Checklist for assessing the quality of quantitative studies

Criteria Yes(2) Partial(1) No(0) N/A

1 Question/ objective sufficiently described? √

2 Study design evident & appropriate? √

3 Method of subject/comparision group selection or source of information/ input variable describe and appropriate?

√

4 Subject ( and comparison group, if applicable) characteristics sufficiently described?

√

36

Yes (2) Partial (1) No (0) NA

5 If interventional and random allocation was possible, was it described? √

6 If interventional and blinding of investigators was possible, was it reported?

√7 If interventional and blinding of subjects

was possible, was it reported? √8 Outcome and (if applicable) exposure

measures well-defined and robust to measurement/misclassification bias? Means of assessment reported

√

37

Yes (2) Partial (1) No (0) NA

9 Sample size appropriate? √10 Analytic methods

described/justified and appropriate?

√

11 Controlled for confounding? √12 Results reported in sufficient

detail? √13 Conclusions supported by the

results? √

38

References • Comprehensive Textbook of Psychiatry, 9th Ed Kaplan & Sadock

• Choi J et al. Reduced telomerase activity in human T lymphocytes exposed to cortisol. Brain Behav Immun 2008; 22: 600–605.

• JE Verhoeven Molecular Psychiatry advance online publication, 12 November 2013; doi:10.1038/mp.2013.151

• Wolkowitz OM, et al. (2011) Leukocyte Telomere Length in Major Depression: Correlations with Chronicity, Inflammation and Oxidative Stress - Preliminary Findings. PLoS ONE 6(3): e17837. doi:10.1371/journal.pone.0017837

• Cawthon RM Telomere measurement by quantitative PCR Nucleic Acids Research 2002, Vol 30 No 10

39

Thank you

40