2.1.2. Younger control subjects

Data for younger controls were derived from two sources. We recruited 225 adults (131 women, 94 men; mean age, 37.9    11.5 years; range 19–67 years). They were recruited from the university students, co-medical personnel, and bank clerk as volunteers. However, the frequency of the l/l genotype among Japanese is low, precluding accurate estimation of genotype distribution based on the small sample size. Therefore, we combined our control 5HTT genotype distribution results with genotype distributions reported in previous studies of Japanese populations (Arinami et al., 1999; Ishiguro et al., 1999; Ishikawa et al., 1999; Katsuragi et al., 1999; Kumakiri et al., 1999; Murakami et al., 1999; Kunugi et al., 2000; Nakamura et al., 1997; Umekage et al., 2003). Participants’ age range of those

snairanetnec-nonnworuodnastcejbusesenapaJfoseidutssuoiverpnimsihpromylop)TTH5(retropsnartninotoresfonoitubirtsiD

studies was 19–77 and they were composed of the volunteers of medical checkup patients, healthy general public and medical staff. The details of those participants were shown in Table 2.

The genotype distribution by gender is shown in Table 2. We compared our results in centenarians with genotype in this combined younger control group. Written informed consent was obtained from all participants or their families. The ethics committee of Keio University School of Medicine approved this study.

2.2. DNA polymorphism

Genomic DNA was obtained from peripheral blood mononuclear cells by phenol extraction. Polymorphisms of the 5HTT gene were determined by a polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) method, as previously described (Lesch et al., 1996).

Statistical analysis was carried out using SPSS software version 11.5J (SPSS, Japan). The x2-test was performed to

Mean (and S.D.) of background characteristics in centenarians

Men Women Total N 59 206 265 Mean age (years) 101.1 (1.8) 101.2 (1.8) 101.2 (1.8) Physical and cognitive functions Barthel Index 61.9 (33.9) 42.0 (33.5) 46.4 (34.5) MMSE 17.0 (8.3) 12.7 (8.3) 13.7 (8.2) Albumin (g/dl) 3.7 (0.4) 3.6 (0.4) 3.6 (0.4)

MMSE, Mini-Mental State Examination.

Table 3

Comparison of serotonin transporter genotype and allele frequency between centenarians and younger controls

Men Women Combined Centenarians Young control Centenarians Young control Centenarians Young control Genotype frequency l/l 3 (5.1%) 28 (3.7%) 19 (9.2%) 20 (3.9%) 22 (8.3%) 58 (4.2%) l/s 22 (37.3%) 213 (28.1%) 61 (29.6%) 149 (29.4%) 83 (31.3%) 408 (29.6%) s/s 34 (57.6%) 516 (68.2%) 126 (61.2%) 338 (66.7%) 160 (60.4%) 911 (66.2%) x2 value l/l vs. l/s and s/s 0.3 n.s. 6.1* 7.8** l/l and l/s vs. s/s 2.8 n.s. 2.5 n.s. 3.8 n.s. Allele frequency L allele 28 (23.7%) 269 (17.8%) 99 (24.0%) 189 (18.6%) 127 (24.0%) 524 (19.0%) S allele 90 (76.3%) 1245 (82.2%) 313 (76.0%) 825 (81.4%) 403 (76.0%) 2230 (81.0%) x2 value 2.6 n.s. 5.3* 7.2** *

evaluate distribution differences in genotype and allele frequency. Genotype  sex analysis of variance (ANOVA) was performed to evaluate associations between 5HTT genotype, personality traits and Barthel Index, MMSE score, and serum albumin concentrations. Multiple comparisons were performed by the Tukey HSD method. Differences were considered significant at p < 0.05. Statistical power was calculated by Sample power version 2 (SPSS, Japan).

observed for women (x2 = 6.1, p < 0.05) but not for men. However, significant difference was not observed between l allele-positive (l/l and l/s, combined) and s/s participants. The frequency of the l allele was significantly higher in centenarians (24.0% versus 19.0%; x2 = 7.1, p < 0.01); this effect was observed only for women (24.0% versus 18.6%; x2 = 5.3, p < 0.05). This null effect in men was not derived from low statistical power to detect a significant difference (a = 0.05, power = 10%, 2-tailed) in this sample.

3. Results

3.2. Association between the 5HTT genotype and physical, cognitive, and biological status

The effects of the 5HTT genotype on NEO-FFI, Barthel Index, MMSE, and serum albumin were analyzed in centenarians (Table 4). No significant effect of genotype was observed for Barthel Index or MMSE and any of NEO- FFI dimensions. A significant main effect of genotype was observed for serum albumin concentration (F = 4.2, p < 0.05). Further, multiple comparison indicated that serum albumin concentrations were higher in association with the l/l genotype than with the s/s genotype ( p < 0.01). Neither a significant gender main effect nor a gender- genotype interaction was observed. We also conducted the same analysis on serum albumin concentration for our

The distribution of genotype and allele frequency for 5HTT in centenarians and control subjects is presented in Table 3. The genotype distributions matched with expecta- tions for a Hardy–Weinberg equilibrium, in younger control. The l/l genotype was uncommon in both centenarians (8.3%) and control subjects (3.9%). The distribution of genotypes between centenarians and young control was compared. Statistically significant difference was observed (l/l versus l/s and s/s, x2 = 7.8, p < 0.01). When an analysis was performed according to gender, a significant distribution difference was

Mean and (S.D.) of NEO-FFI, Barthel Index, Mini-Mental State Examination and serum albumin concentration by 5HTT genotypes in centenarians