OCTO TwinOrigins of Variance in the Old-Old

General presentationBoo Johansson

National Institute on Aging: AG 08861

Life span

Friday Harbor Psychometrics Workshop 2010

Acknowledgements

• Funded in part by Grant R13AG030995-01A1 from the National Institute on Aging

• The views expressed in written conference materials or publications and by speakers and moderators do not necessarily reflect the official policies of the Department of Health and Human Services; nor does mention by trade names, commercial practices, or organizations imply endorsement by the U.S. Government.

Major Swedish Longitudinal Aging Studies ..at that time

- population-based

- longitudinal design - possible to conduct

- informative

H70 (70+), OCTO (84+), …. SATSA (55+) ….??

Background for the OCTO Twin Study

- Observations of substantial individual differences in rate and patterns of aging - Understanding the origins of this variability is of fundamental importance – What are the relative contributions of genetic and environmental influences?

- Limited information about the oldest old age segement in the above respect

1988

The planning for a Twin Study of the Old-Old (80 +) started ~ 20 years ago (1988)

H70,OCTO, SATSA

..the missing ‘piece’

OCTO Twin

OCTO Twin - OVERALL AIM

• To estimate the relative contributions of environmental and genetic influences to the variability in health and biobehavioral functioning …..

• at each measurement occasion as well as to longitudinal change and continuity during inter-occasion intervals

..in a life span genetic and environmental influenceperspective

An individual difference approach focus on variance among individuals within a population

------------------------Directs our attention to the origins of variability

within an age group

-----------------------Thus,

we become compelled to search for the fundamental sources for observed differences

in a specific phenotype

The prototypic twin design

Monozygotic (MZ) pairsand

Dizygotic (like-sex) pairs

• compared with respect to intra-pair similarities

MZ - monozygotic twins share 100% of all genetic influences

Same birthday Same parents

DZ - dizygotic twins share on average 50% of genetic influences

  Wave 1 Wave 2 Wave 3 Wave 4 Wave 5 

 

1991 1993 1995 1997 1999March May April March March

 

 

1994 1996 1998 2000 2002March March March March March

The OCTO Twin Design

5 measurement occasions, 2-years apart

Domains at focus

Health and functional capacityCognitive functioning Personality and personal controlPsychological well-beingInterpersonal functioning

Using largely the same measures as in reference studies (H70, OCTO, SATSA

Health and functional capacity

- Self-rated health- Self-reported medical history (”checklist”)

- Sensory (Vision, hearing)- PB, Pulse, BMI - Functional tests of balance and gait- Grip strength, lung capacity

- Contacts with the health care system (district nurse, physicans, and hospital)- Information from medical (ICD-10 coded) and dental records - Medications (ATC –codes)

- Blood chemistry panel

Memory and Cognition

- Cog.status – MMSE, Clock Test, Coin Test - Inductive reasoning – figure logic- Psychomotor speed - Psif, Digit-Symbol- Visuospatial ability – Koh’s Block- Primary memory – Digit Span- Semantic memory – Synonyms - Information- Episodic memory – Prose, MIR, Thurstone Picture memory

Dementia work-up individuals suspected for dementia

- Review of memory and cognitive tests- Informant neuropsychological interview- Review of medical records and supplement information

- A consensus diagnosis conference (DSM, ICD, NINCDS-ADRA, NINDS-AIREN, etc)

Personality and Personal Control

- Eysenck Personality Inventory (EPI)- Global Locus of Control- Heatlh Locus of Control

Psychological Well-being

- Life Satisfaction Scale (LSI-Z)- Depressive symptoms scale (CES-D)- Open ended questions, e.g. significant life events

Interpersonal functioning

- Social networks- Contact frequencies- Confidants- Loneliness

Functional capacity

- ADL Apparatus Test- ADL and IADL Scales (Self and RN ratings) - Need for help in ADL/IADL- Home help/institutional care- Technical aids, mobility, hearing, vision

Testing session

Supplement information

Twin Registry Ratings by RNs’ and PDMedical recordsDental records

Death certificates

Dementia work-up Autopsy/neuropathology

Procedure

- In-person/individual examinations in place of residence across the country

- by trained and supervised RNs- using a broad-based biobehavioral battery

Members of a twin pair never investigated by same RN to avoid expectation bias.

The RNs’ blind to zygosity.

The OCTO Twin Sample

• Twins in complete pairs, 80 years and older at baseline (< 1913)

• MZ (monozygotic) twin pairs (N=149) and same-sex DZ (dizygotic) twin pairs (N=202)

• All survivors followed longitudinally across

5 waves, 2-years apart

Population selection in OCTO Twin: Number of tested individuals and pairs across waves (8y)

W1 W2 W3 W4 W5

MZ DZ MZ DZ MZ DZ MZ DZ MZ DZ

Pairs 149 202 98 137 65 79 43 43 20 23

Men 56 61 38 40 22 23 12 10 5 4Women 93 141 60 97 43 56 32 33 15 19

Total 351 235 144 86 43

MZ % 42,5 41,7 45,1 50,0 46,5

Individuals298 404 235 333 178 252 142 173 100 122

Men 112 122 90 101 65 77 47 43 31 26Women 186 282 145 232 113 175 95 130 69 96 Total 702 (704) 568 430 315 222

MZ % 42,5 41,4 41,4 45,1 42,5

R-rate > 90%

• SATSA• OCTO Twin

• Gender• Harmony

Ongoing Swedish Twin Studieson Aging

Boo Johansson