Materials and Methods

Study participants. The Study cohort (N 1151) consists of all participants aged ae1=9 90 years who were alive on January 1, 2003, and were part of the initial Leisure World Cohort Study (Corrada et al., 2008; Paganini-Hill et al., 2011). The Leisure World Cohort Study was estab- lished in 1981, when a health survey was mailed to all residents who at that time owned homes in the Leisure World retirement community, Laguna Woods, California. A total of 13,979 residents (61%) returned the questionnaire and constitute this cohort. The median age of subjects when they joined the cohort was 73 years (range, 44–107 years). Reflect- ing the characteristics of the community, the cohort was primarily of Europeanancestry(98%)andhighlyeducated(67%withsomecollegeto advanced degree). An additional questionnaire on current (2003 to pres- ent) activity levels was obtained from 233 participants, using questions appropriate for this age group. The longitudinal data in this large cohort havebeenusedtoconcludethatspendingmoretimeinphysicalactivities

     DRD4 7RIXDRD4 NON-7RIXNoWowud

ACTIVITY (HRS)5thcoasth50thPercentileZ75th gsth

Figure3. DRD4genotypeandself-reportedactivity.Thenumberofhoursperdayofactivity reported in 1981 is plotted versus participants with a DRD4 7R/x genotype (black bars) or non-DRD4 7R/x genotype (striped bars). Comparisons are shown at the 5th, 25th, 50th, 75th, and95thpercentiles.IncludingDRD42R/xand3R/xindividualswiththeDRD47R/xindividuals instead of the non-7R/x individuals (Ding et al., 2002; Grady et al., 2003; Wang et al., 2004; Gradyetal.,2005)gavecomparableactivityleveldifferences(i.e.,anancestral4R/4Rvsnon- 4R/4Rdivision).

Figure2. ComparisonofexpectedtoobservedDRD4genotypes.Oldest-oldindividuals(N(cid:1) 310) were genotyped at the exon 3 DRD4 polymorphism (Fig. 1, inset) and compared with population-based European ancestry control sample DRD4 genotypes (Expected, N ressv= 2902). TheDRD47R/xcategory(blackbars)containsindividualswithatleastone7R(orderived7R,i.e., 5R, 6R, 8R, 9R, 10R, and 11R) allele, and the non-7R/x category (striped bars) contains the remainingindividuals.Theexpectedandobservedfractionforeachcategoryisshown.Expected 7R/x(N(cid:1)635),Non7R/x(N(cid:1)2267);90(cid:2)observed7R/x(N(cid:1)113),Non7R/x(N(cid:1)197); Female7R/x(N(cid:1)86),Non7R/x(N(cid:1)133);Male7R/x(N(cid:1)27),Non7R/x(N(cid:1)64).Asterisks denote observed differences significant at p vomear=3  3.5 EMM!5X 1 10(cid:4)9 (90(cid:2) years), p ”.= 1.7 mmr7X1 10(cid:4)9 (Female),andp(cid:1)0.034(Male)(seetext).

tenrisky)behaviorsassociatedwithDRD47Rallelesearlierinlife, such as ADHD and drug abuse, which have a significant male bias (Swanson et al., 2000; Grady et al., 2003; Olsson et al., 2011). Allele frequencies at 20 randomly chosen polymorphisms in nine unrelated genomic regions (CFTR, ERCC8, ERBB4, FANCC, HTERT, NRF1, RTN1, SLC6A3, and UCP3) did not differ significantly among the oldest-old individuals, younger control individuals, or HapMap European ancestry populations (International HapMap Consortium et al., 2007).

termine the haplotype (273 alleles). The common 7R(1-2-6-5-2-5-4) haplotype or 7R derivatives were the predominant 7R sequences, with the fraction of common to rare haplotypes similar to that observed in prior population studies (Ding et al., 2002; Wang et al., 2004).

and homozygous knock-out (KO) mice (Rubinstein et al., 1997) were assigned to either an enriched environment (EE; housed with other mice and with access to toys and running wheels) or a deprived environment (DE; housed in isolation in standard cages) and maintained under these conditions for their lifespan. Mice were divided into six groups distin- guished by their genotype (WT, HT, and KO) and environmental exposure (EE and DE) with the following sample sizes: WT (DE ahi’  66, EE  51), HT (DE   31, EE  26), and KO (DE  34, EE ry a \ey 34). Age at time of death was recorded for all animals following guidelines previ- ouslyoutlined(Ullman-Cullere´ andFoltz,1999).Locomotoractivitywas tested bimonthly for 90 min using an activity monitoring system (Mini Mitter). Differences in longevity and locomotor activity between groups were assessed using SAS 9.1 and STRATA 7.0. Experiments followed the Guide for the Care and Use of Laboratory Animals (Quimby et al., 2010).

In the oldest-old, we also observed a significant association between the 7R/x genotype and higher reported activity levels in both males and females (Fig. 3). This association was observed not only for measures obtained in 1981, when the mean self- reported activity level differed by 45% (1.42 vs 0.98 h; (cid:2)2 me 5.07, p <p»= 0.024 when measured as a categorical variable; and t   2.40, os»= p 0.018 when measured as a continuous variable), but also when the measured variable was current self-reported activity ((cid:2)2  4.43, sim 24= | p 0.033). Oldest-old participants with the DRD4 7R/x genotype 5 >? were twice as likely to report exercising 2 h/d in 1981 (top 20%; (cid:2)2 “iw &' 17.33, p  1.64 “<P 10(cid:4)5; Fig. 3). The correlation of higher activity with DRD4 7R/x genotype was not confounded by age, gen- der, alcohol intake, BMI, or medical history, similar to results ob- tainedinthelargerLeisureWorldcohort(Paganini-Hilletal.,2011). The proportion of the variance in physical activity explained by DRD4 7R in this oldest-old population was r2 en. 0.023.

Results