International Journal of Epidemiology, 2014, 1726–1735 doi: 10.1093/ije/dyu012 Advance Access Publication Date: 16 March 2014 Cohort Profile
Cohort Profile
Cohort Profile: The Hawai‘i Family Study of Cognition Jane MM Onoye,1,2,* Earl S Hishinuma,1 John J McArdle,3,4 Alan B Zonderman,5 R Janine Bumanglag1 and Junji Takeshita1,2 Downloaded from http://ije.oxfordjournals.org/ at University of Strathclyde on January 8, 2015
1
Department of Psychiatry, University of Hawai‘i at Ma¯noa, Honolulu, Hawai‘i, USA, 2Queen’s Medical Center, Honolulu, Hawai‘i, USA, 3Department of Psychology, University of Southern California, Los Angeles, CA, USA, 4Longitudinal Research Institute, Charlottesville, VA, USA and 5National Institute on Aging, Behavioral Epidemiology Section, Baltimore, MD, USA *Corresponding author. Department of Psychiatry, University of Hawai‘i at Ma¯noa, 1356 Lusitana Street, 4th Floor, Honolulu, HI 96813, USA. E-mail: [email protected] Accepted 9 January 2014
Abstract Intergenerational longitudinal studies over the lifespan provide valuable information for understanding the contexts and dynamic relations among cognition, family and health in adults and the elderly. The Hawai‘i Family Study of Cognition (HFSC), initiated in the early 1970s, included a cohort of over 6500 individuals representing over 1800 families of parents and their offspring. The HFSC gathered data on cognitive, personality, biological and other psychosocial variables, and provided novel information on the nature of cognitive abilities, especially on family issues. Some families were reassessed with short-term retesting in the 1970s. A select sample of offspring and their siblings and spouses were re-measured in the 1980s. Decades later, a 40-year follow-up of the original HFSC cohort was facilitated by the availability of contemporary tracking and tracing methods and internet-based testing. A subgroup of the original HFSC participants was re-contacted and retested on contemporary cognitive as well as socio-demographic and health measures. In this paper, we describe the original HFSC cohort and the design and methodology of the re-contact and retest studies of the HFSC, plans for expanding the re-contact and retesting, as well as directions for future research and collaborations. The Principal Investigator may be contacted for more information regarding the application, review and approval process for data access requests from qualified individuals outside the project. Key words: Cognition, family, longitudinal studies, ethnic groups
C The Author 2014; all rights reserved. Published by Oxford University Press on behalf of the International Epidemiological Association V
1726
1727
International Journal of Epidemiology, 2014, Vol. 43, No. 6
Key Messages • The HFSC provided findings consistent with genetic influences on cognition and added contribution of environmental
variables. • From the HFSC’s original 15-subscale battery of cognitive abilities, early examination using traditional factor analyses
(i.e. not structural equation modelling) found a four-factor structure (verbal, spatial visualization, visual memory, and perceptual speed and accuracy) that was relatively robust across ethnic groups, age and families. • Later contemporary advanced structural equation modelling allowed some refinement resulting in a six-factor struc-
ture (verbal, fluid reasoning, memory, speed of processing, visuo-spatial and social perception) with the conclusion that cognitive differences were larger within families than between families. • The influence of intelligence on social attainment (education and occupational) is likely moderated by social, cultural
and historical factors.
There is growing recognition of the importance of scientific theories on the structure and function of broad human cognitive abilities through the lifespan, as well as the application of these theories to improve the quality of life of individuals as they grow older.1 Scientific debates have included questions about how cognition takes shape during development, measurement of group differences, the separate and combined influences of nature vs nurture, and family effects.2 A common feature of family theory, ‘positive family transmission’ of cognition and personality, is based on genetics, education, socialization, birth order, altruism and other aspects of family systems.3 In addition, the covariation and interaction of cognition and personality are of great interest.4 Moreover, little work in this area has included multi-ethnic populations such as Asian Americans and Pacific Islanders.5–9 The Hawai‘i Family Study of Cognition (HFSC) provided a great deal of scientific information on this debate, especially on family issues. Initiated in the 1970s, the principal objective of the HFSC was to assess genetic and environmental bases of performance on various tests of cognitive abilities. Beginning in 1972, the HFSC took place at the University of Hawai‘i at Ma¯noa in Honolulu, Hawai‘i, and was a collaborative effort between investigators at the University of Hawai‘i (G Ashton, MP Mi, MN Rashad, R Johnson, later FM Ahern) and the University of Colorado (GE McClearn, JC DeFries, JR Wilson, SG Vandenberg, later AR Kuse). The work was funded by the US National Science Foundation and the US National Institute of Child Health and Human Development. Later follow-up studies were supported by the US National Institute on Alcoholism and Alcohol Abuse and the US National Institute of Child Health and Human Development. Over several decades, developments in statistical approaches allowed contemporary analyses of the HFSC,
including family-linked data across two generations,10 and also revived interest in a follow-up of the HFSC participants. Also, given the large initial sample and the array of techniques in tracking and tracing individuals through the internet or web-based services currently available,11 a subsequent long-term follow-up study was initiated in 2010 to re-contact and in 2011 to retest HFSC participants to further examine the relationship of family and cognitive factors with health and ageing. The revival of the HFSC was a collaborative effort among investigators at the University of Hawai‘i, University of Southern California, Longitudinal Research Institute and the National Institute on Aging, and has been supported by the National Institute on Aging, the University of Southern California and The Queen’s Medical Center.
Who is in the cohort? The HFSC from the 1970s included a large number of volunteer families (Nf ¼ 1818) and individuals (Ni ¼ 6586). Their participation was solicited by letters, radio and television public service announcements, contact through clubs and organizations, and personal referral from previous participants. From 1972 to 1976, families were tested in small groups at the university or community auditoria, over several hours. Each family was paid $50 for participating. The HFSC cohort included the parent generation (Np ¼ 3636, 55%; median age ¼ 43.6 years; 95% aged 35–55), and the child generation (Nc ¼ 2950, 45%; median age ¼ 16.1 years; 95% aged 14–23). There were almost equal numbers of males and females in each generation. The HFSC families included: (i) Americans of European ancestry (54%); (ii) Americans of Japanese ancestry (21%); (iii) Americans of Chinese ancestry (7%); and (iv) Americans of Native Hawaiian (indigenous people of
Downloaded from http://ije.oxfordjournals.org/ at University of Strathclyde on January 8, 2015
Why was the cohort set up?
International Journal of Epidemiology, 2014, Vol. 43, No. 6
Hawai‘i) ancestry (10%). Table 1 summarizes the sociodemographic characteristics of the parent and offspring generations from the original sample compared with the general Hawai‘i population.
1728
Table 1. Socio-demographic characteristics of HFSC original cohort compared with general Hawai‘in population Characteristics
HFSC cohort %
Age group in years
Parent Child generation generation
How often have they been followed up? Earlier follow-ups of the HFSC cohort
Revival of the HFSC Tracking and tracing the HFSC cohort After more than three decades from the original assessment in the 1970s, a follow-up study of tracking and tracing the cohort was initiated in 2010 (Table 2) to construct an updated database of contact information. All hereafterdescribed tracking/tracing, re-contact and retesting procedures for the revived HFSC were conducted in accordance with review and approval by the University of Hawai‘i institutional review board. In 2009–10, we assessed multiple approaches for feasibility of tracking and tracing the HFSC cohort [e.g. web-based search engines, directories, locator services, local alumni directories, state and county public records and the National Death Index of the Centers for Disease Control and Prevention (CDC)]. Due to limitations of accessibility and cost, and factoring geographical dispersion of the original HFSC families, the most productive approach resulted in a third-party vendor conducting a large-scale search for updated contact and mortality information using publicly searchable databases based on last known addresses and/or phone numbers from the 1970s or 1980s.Combined with prior information from the CDC’s National Death Index, a tracking search for 4328 individuals without known mortality records yielded a match rate of approximately 46% for a current known address. Additional updated mortality records were found on 2.15% of the batched records. Combined with the earlier mortality information, overall we found that about 67%
Less than high school High school or equivalent Technical or trade school Some college College degree or higher
0.1 2.2 12.9 17.4 13.1 6.4 2.5 0.5 0.1
12.7 26.8 4.1 1.0 0.2 0 0 0 0 0 0 0
10.5 9.3 10.5 7.8 6.2 6.1 6.3 6.0 5.0 4.0 3.0 5.8
49.5 50.5
52.0 48.1
53.7 21.0 6.7 9.9 8.7
3.7 11.5 8.7 12.4 18.8
34.5 2.8 0.4 5.4 1.6
39.2 28.3 6.8 9.3 16.4 25þ 14–24 years years 19.1 9.9c 18.0 10.6d e
6.0 7.0
c c
1.0
a Includes part-Native Hawaiian as classification of ethnicity defined in the original HFSC studies and the US Census. b Includes persons of mixed-ethnicity that were not part-Native Hawaiian. c Percent estimated from school enrollment age 14 – 17 years old and level of school completed for 18 – 24 years old. d Percent breakdown from Census estimated based on population aged 18 and older (US Census, 1970). e Not reported for age group.
of ‘the parent generation were deceased, and about 95% of the child generation were still living. Re-contact and retesting. Using the updated contact database, in 2010–11 we attempted to re-contact a subset of the original participants still living from among those with multiple previous follow-ups (Nf ¼ 307 families; Ni ¼ 555) to gather basic current demographic information and gauge interest in participating in a follow-up study. Because these participants were receptive to retesting during the 1970s or 1980s, we predicted they would be the most receptive to re-engagement decades later. Participants were mailed a packet which included an introductory cover letter and newsletter, $10 for reading the materials, informed consent
Downloaded from http://ije.oxfordjournals.org/ at University of Strathclyde on January 8, 2015
The HFSC was not originally designed as a longitudinal observational study; however, some families participated in a short-term repeat testing with supplemental measures in 1975 and 1976. Educational and occupational attainments for the offspring were assessed in 1983. In a follow-up study in 1987–88, many of the child generation, including siblings, were retested on the original measures12,13 and additional scales. Spouses of the HFSC children were also tested in the 1980s follow-up study.13 Participants from the continental USA (40%) mailed back completed questionnaires, and local residents brought in the completed questionnaire and were retested in person. The timeline of follow-ups of the HFSC cohort is depicted in Table 2.
10–14 15–19 20–24 25–29 30–34 35–39 40–44 45–49 50–54 55–59 60–64 65þ Sex Female Male Ethnicity European American Japanese American Chinese American Native Hawaiiana Otherb Education
Census 1970 Hawai‘i population %
i ¼ individuals; f ¼ families; p ¼ HFSC
Response rate
Tracking and tracing
Mortality
HFSC grandchildren
Spouses of HFSC children
participation rate ¼ 105/118 (84%)
• Family
Nf ¼ 105 Ni ¼ 393
tion rate ¼ 353/ 437(81%)
ual participation rate ¼ 437/718(61%) • Children retesting family participation rate ¼ 275/ 422 (65%)
• Children retesting individ-
tacted ¼ 530/547 (97%) • Undeliverable ¼ 7/547 (1%) • From Family tracking, 718 HFSC Children(422 families) located and contacted
• Family participa-
• Families located and con-
located ¼ 1200/ 1818 (66%) • Families contacted ¼ 437 • Undeliverable ¼ 14/ 437 (3%)
Nsp ¼ 175
Nf ¼ 275 Nc ¼ 437
1987 – 1988: Follow-up Long-term Re-contact subgroup of 1976 Families & RetestingHFSC Children
• Families
Nf ¼ 353 nc ¼ 561
1983: Follow-up Recontact 1976 Families
parents; c ¼ HFSC children; gc ¼ HFSC grandchildren; sp ¼ spouses of HFSC children.
participation rate ¼ 118/165 (72%)
• Family
Nf ¼ 118 Ni ¼ 456 np ¼ 236 nc ¼ 220
Nf ¼ 1818 Ni ¼ 6586 np ¼ 3636 nc ¼ 2950
1976: Follow-up Additional Testing of Families from 1975 Retesting
• Overall participation
• Overall response
(34%) • Additional deceased notification ¼ 8/555 (1%)
• Non-response ¼ 191/555
rate ¼ 280/555 (50%) • Agree to contact for follow-up study ¼ 230/555 (41%) • Declined ¼ 50/555 (9%)
(14%)
• Undeliverable ¼ 76/555
cation ¼ 1/341(
Cohort Profile
Cohort Profile: The Hawai‘i Family Study of Cognition Jane MM Onoye,1,2,* Earl S Hishinuma,1 John J McArdle,3,4 Alan B Zonderman,5 R Janine Bumanglag1 and Junji Takeshita1,2 Downloaded from http://ije.oxfordjournals.org/ at University of Strathclyde on January 8, 2015
1
Department of Psychiatry, University of Hawai‘i at Ma¯noa, Honolulu, Hawai‘i, USA, 2Queen’s Medical Center, Honolulu, Hawai‘i, USA, 3Department of Psychology, University of Southern California, Los Angeles, CA, USA, 4Longitudinal Research Institute, Charlottesville, VA, USA and 5National Institute on Aging, Behavioral Epidemiology Section, Baltimore, MD, USA *Corresponding author. Department of Psychiatry, University of Hawai‘i at Ma¯noa, 1356 Lusitana Street, 4th Floor, Honolulu, HI 96813, USA. E-mail: [email protected] Accepted 9 January 2014
Abstract Intergenerational longitudinal studies over the lifespan provide valuable information for understanding the contexts and dynamic relations among cognition, family and health in adults and the elderly. The Hawai‘i Family Study of Cognition (HFSC), initiated in the early 1970s, included a cohort of over 6500 individuals representing over 1800 families of parents and their offspring. The HFSC gathered data on cognitive, personality, biological and other psychosocial variables, and provided novel information on the nature of cognitive abilities, especially on family issues. Some families were reassessed with short-term retesting in the 1970s. A select sample of offspring and their siblings and spouses were re-measured in the 1980s. Decades later, a 40-year follow-up of the original HFSC cohort was facilitated by the availability of contemporary tracking and tracing methods and internet-based testing. A subgroup of the original HFSC participants was re-contacted and retested on contemporary cognitive as well as socio-demographic and health measures. In this paper, we describe the original HFSC cohort and the design and methodology of the re-contact and retest studies of the HFSC, plans for expanding the re-contact and retesting, as well as directions for future research and collaborations. The Principal Investigator may be contacted for more information regarding the application, review and approval process for data access requests from qualified individuals outside the project. Key words: Cognition, family, longitudinal studies, ethnic groups
C The Author 2014; all rights reserved. Published by Oxford University Press on behalf of the International Epidemiological Association V
1726
1727
International Journal of Epidemiology, 2014, Vol. 43, No. 6
Key Messages • The HFSC provided findings consistent with genetic influences on cognition and added contribution of environmental
variables. • From the HFSC’s original 15-subscale battery of cognitive abilities, early examination using traditional factor analyses
(i.e. not structural equation modelling) found a four-factor structure (verbal, spatial visualization, visual memory, and perceptual speed and accuracy) that was relatively robust across ethnic groups, age and families. • Later contemporary advanced structural equation modelling allowed some refinement resulting in a six-factor struc-
ture (verbal, fluid reasoning, memory, speed of processing, visuo-spatial and social perception) with the conclusion that cognitive differences were larger within families than between families. • The influence of intelligence on social attainment (education and occupational) is likely moderated by social, cultural
and historical factors.
There is growing recognition of the importance of scientific theories on the structure and function of broad human cognitive abilities through the lifespan, as well as the application of these theories to improve the quality of life of individuals as they grow older.1 Scientific debates have included questions about how cognition takes shape during development, measurement of group differences, the separate and combined influences of nature vs nurture, and family effects.2 A common feature of family theory, ‘positive family transmission’ of cognition and personality, is based on genetics, education, socialization, birth order, altruism and other aspects of family systems.3 In addition, the covariation and interaction of cognition and personality are of great interest.4 Moreover, little work in this area has included multi-ethnic populations such as Asian Americans and Pacific Islanders.5–9 The Hawai‘i Family Study of Cognition (HFSC) provided a great deal of scientific information on this debate, especially on family issues. Initiated in the 1970s, the principal objective of the HFSC was to assess genetic and environmental bases of performance on various tests of cognitive abilities. Beginning in 1972, the HFSC took place at the University of Hawai‘i at Ma¯noa in Honolulu, Hawai‘i, and was a collaborative effort between investigators at the University of Hawai‘i (G Ashton, MP Mi, MN Rashad, R Johnson, later FM Ahern) and the University of Colorado (GE McClearn, JC DeFries, JR Wilson, SG Vandenberg, later AR Kuse). The work was funded by the US National Science Foundation and the US National Institute of Child Health and Human Development. Later follow-up studies were supported by the US National Institute on Alcoholism and Alcohol Abuse and the US National Institute of Child Health and Human Development. Over several decades, developments in statistical approaches allowed contemporary analyses of the HFSC,
including family-linked data across two generations,10 and also revived interest in a follow-up of the HFSC participants. Also, given the large initial sample and the array of techniques in tracking and tracing individuals through the internet or web-based services currently available,11 a subsequent long-term follow-up study was initiated in 2010 to re-contact and in 2011 to retest HFSC participants to further examine the relationship of family and cognitive factors with health and ageing. The revival of the HFSC was a collaborative effort among investigators at the University of Hawai‘i, University of Southern California, Longitudinal Research Institute and the National Institute on Aging, and has been supported by the National Institute on Aging, the University of Southern California and The Queen’s Medical Center.
Who is in the cohort? The HFSC from the 1970s included a large number of volunteer families (Nf ¼ 1818) and individuals (Ni ¼ 6586). Their participation was solicited by letters, radio and television public service announcements, contact through clubs and organizations, and personal referral from previous participants. From 1972 to 1976, families were tested in small groups at the university or community auditoria, over several hours. Each family was paid $50 for participating. The HFSC cohort included the parent generation (Np ¼ 3636, 55%; median age ¼ 43.6 years; 95% aged 35–55), and the child generation (Nc ¼ 2950, 45%; median age ¼ 16.1 years; 95% aged 14–23). There were almost equal numbers of males and females in each generation. The HFSC families included: (i) Americans of European ancestry (54%); (ii) Americans of Japanese ancestry (21%); (iii) Americans of Chinese ancestry (7%); and (iv) Americans of Native Hawaiian (indigenous people of
Downloaded from http://ije.oxfordjournals.org/ at University of Strathclyde on January 8, 2015
Why was the cohort set up?
International Journal of Epidemiology, 2014, Vol. 43, No. 6
Hawai‘i) ancestry (10%). Table 1 summarizes the sociodemographic characteristics of the parent and offspring generations from the original sample compared with the general Hawai‘i population.
1728
Table 1. Socio-demographic characteristics of HFSC original cohort compared with general Hawai‘in population Characteristics
HFSC cohort %
Age group in years
Parent Child generation generation
How often have they been followed up? Earlier follow-ups of the HFSC cohort
Revival of the HFSC Tracking and tracing the HFSC cohort After more than three decades from the original assessment in the 1970s, a follow-up study of tracking and tracing the cohort was initiated in 2010 (Table 2) to construct an updated database of contact information. All hereafterdescribed tracking/tracing, re-contact and retesting procedures for the revived HFSC were conducted in accordance with review and approval by the University of Hawai‘i institutional review board. In 2009–10, we assessed multiple approaches for feasibility of tracking and tracing the HFSC cohort [e.g. web-based search engines, directories, locator services, local alumni directories, state and county public records and the National Death Index of the Centers for Disease Control and Prevention (CDC)]. Due to limitations of accessibility and cost, and factoring geographical dispersion of the original HFSC families, the most productive approach resulted in a third-party vendor conducting a large-scale search for updated contact and mortality information using publicly searchable databases based on last known addresses and/or phone numbers from the 1970s or 1980s.Combined with prior information from the CDC’s National Death Index, a tracking search for 4328 individuals without known mortality records yielded a match rate of approximately 46% for a current known address. Additional updated mortality records were found on 2.15% of the batched records. Combined with the earlier mortality information, overall we found that about 67%
Less than high school High school or equivalent Technical or trade school Some college College degree or higher
0.1 2.2 12.9 17.4 13.1 6.4 2.5 0.5 0.1
12.7 26.8 4.1 1.0 0.2 0 0 0 0 0 0 0
10.5 9.3 10.5 7.8 6.2 6.1 6.3 6.0 5.0 4.0 3.0 5.8
49.5 50.5
52.0 48.1
53.7 21.0 6.7 9.9 8.7
3.7 11.5 8.7 12.4 18.8
34.5 2.8 0.4 5.4 1.6
39.2 28.3 6.8 9.3 16.4 25þ 14–24 years years 19.1 9.9c 18.0 10.6d e
6.0 7.0
c c
1.0
a Includes part-Native Hawaiian as classification of ethnicity defined in the original HFSC studies and the US Census. b Includes persons of mixed-ethnicity that were not part-Native Hawaiian. c Percent estimated from school enrollment age 14 – 17 years old and level of school completed for 18 – 24 years old. d Percent breakdown from Census estimated based on population aged 18 and older (US Census, 1970). e Not reported for age group.
of ‘the parent generation were deceased, and about 95% of the child generation were still living. Re-contact and retesting. Using the updated contact database, in 2010–11 we attempted to re-contact a subset of the original participants still living from among those with multiple previous follow-ups (Nf ¼ 307 families; Ni ¼ 555) to gather basic current demographic information and gauge interest in participating in a follow-up study. Because these participants were receptive to retesting during the 1970s or 1980s, we predicted they would be the most receptive to re-engagement decades later. Participants were mailed a packet which included an introductory cover letter and newsletter, $10 for reading the materials, informed consent
Downloaded from http://ije.oxfordjournals.org/ at University of Strathclyde on January 8, 2015
The HFSC was not originally designed as a longitudinal observational study; however, some families participated in a short-term repeat testing with supplemental measures in 1975 and 1976. Educational and occupational attainments for the offspring were assessed in 1983. In a follow-up study in 1987–88, many of the child generation, including siblings, were retested on the original measures12,13 and additional scales. Spouses of the HFSC children were also tested in the 1980s follow-up study.13 Participants from the continental USA (40%) mailed back completed questionnaires, and local residents brought in the completed questionnaire and were retested in person. The timeline of follow-ups of the HFSC cohort is depicted in Table 2.
10–14 15–19 20–24 25–29 30–34 35–39 40–44 45–49 50–54 55–59 60–64 65þ Sex Female Male Ethnicity European American Japanese American Chinese American Native Hawaiiana Otherb Education
Census 1970 Hawai‘i population %
i ¼ individuals; f ¼ families; p ¼ HFSC
Response rate
Tracking and tracing
Mortality
HFSC grandchildren
Spouses of HFSC children
participation rate ¼ 105/118 (84%)
• Family
Nf ¼ 105 Ni ¼ 393
tion rate ¼ 353/ 437(81%)
ual participation rate ¼ 437/718(61%) • Children retesting family participation rate ¼ 275/ 422 (65%)
• Children retesting individ-
tacted ¼ 530/547 (97%) • Undeliverable ¼ 7/547 (1%) • From Family tracking, 718 HFSC Children(422 families) located and contacted
• Family participa-
• Families located and con-
located ¼ 1200/ 1818 (66%) • Families contacted ¼ 437 • Undeliverable ¼ 14/ 437 (3%)
Nsp ¼ 175
Nf ¼ 275 Nc ¼ 437
1987 – 1988: Follow-up Long-term Re-contact subgroup of 1976 Families & RetestingHFSC Children
• Families
Nf ¼ 353 nc ¼ 561
1983: Follow-up Recontact 1976 Families
parents; c ¼ HFSC children; gc ¼ HFSC grandchildren; sp ¼ spouses of HFSC children.
participation rate ¼ 118/165 (72%)
• Family
Nf ¼ 118 Ni ¼ 456 np ¼ 236 nc ¼ 220
Nf ¼ 1818 Ni ¼ 6586 np ¼ 3636 nc ¼ 2950
1976: Follow-up Additional Testing of Families from 1975 Retesting
• Overall participation
• Overall response
(34%) • Additional deceased notification ¼ 8/555 (1%)
• Non-response ¼ 191/555
rate ¼ 280/555 (50%) • Agree to contact for follow-up study ¼ 230/555 (41%) • Declined ¼ 50/555 (9%)
(14%)
• Undeliverable ¼ 76/555
cation ¼ 1/341(
