Relation of high neuroticism with increased methylation of the BDNF gene

Figures & data

Figure 1 The CG sites analyzed in the promoter IV region of the BDNF gene.

Notes: The presented genomic region is Chr11: 27723159-27723246 (University of California, Santa Cruz Genome Browser, Human February 2009, GRCh37/hg19). Bold characters indicate the CG sites in the examined region.
Abbreviations: BDNF, brain-derived neurotrophic factor; CREB, cAMP response element-binding protein.

Table 1 Demographic characteristics, five domain scores of the NEO PI-R and methylation levels of the BDNF gene of the subjects

Characteristics	Number
Age, years	22.4±0.6
Male/female, n	49/49
BMI, kg/m^2	21.0±2.5
NEO PI-R, score
Neuroticism	106.3±23.5
Extraversion	99.3±21.7
Openness to experience	115.1±15.1
Agreeableness	108.9±18.9
Conscientiousness	98.0±21.4
BDNF gene methylation
1st CG site	2.13±1.50
2nd CG site	0.20±0.54
Mean of 1st and 2nd CG sites	1.16±0.87

Note: The figures on the table show mean±SD.

Abbreviations: BDNF, brain-derived neurotrophic factor; BMI, body mass index; NEO PI-R, NEO Personality Inventory-Revised.

Table 2 Correlations among NEO PI-R scores, BMI and the BDNF gene methylation levels

	1	2	3	4	5	6	7	8
1. Neuroticism
2. Extraversion	−0.372
3. Openness to experience	0.046	0.312**
4. Agreeableness	−0.326**	0.021	0.074
5. Conscientiousness	−0.448**	0.420**	0.169	0.315**
6. BMI	0.075	−0.204*	−0.205*	−0.165	−0.286
7. Methylation of 1st CG site	0.230*	−0.069	0.149	0.132	−0.011	−0.044
8. Methylation of 2nd CG site	−0.151	0.048	0.026	0.031	0.118	−0.097	0.295**
9. Mean of 1st and 2nd CG sites	0.150	−0.042	0.137	0.126	0.047	−0.068	0.956**	0.562**

Notes: The figures on the table show Pearson’s correlation coefficients.

* p<0.05,

** p<0.01.

Abbreviations: BDNF, brain-derived neurotrophic factor; BMI, body mass index; NEO PI-R, NEO Personality Inventory-Revised.

Figure 2 Relationship between neuroticism and methylation levels of the 1st CG site of the BDNF gene.

Abbreviation: BDNF, brain-derived neurotrophic factor.

Table 3 Effects of NEO PI-R scores and sex on methylation levels of the BDNF gene

	Male	Female	F value
			NEO PI-R	Sex	NEO PI-R × sex
1st CG site, low vs high
Neuroticism	1.68±1.58 vs 2.47±1.31	1.75±1.34 vs 2.63±1.64	8.125**	0.007	0.009
Extraversion	1.95±1.52 vs 2.31±1.42	2.52±1.70 vs 1.89±1.38	0.244	0.003	2.579
Openness to experience	1.70±1.54 vs 2.54±1.30	2.16±1.78 vs 2.17±1.31	1.808	0.002	1.874
Agreeableness	1.90±1.45 vs 2.38±1.51	2.17±1.87 vs 2.16±1.31	0.585	0.010	0.596
Conscientiousness	2.03±1.45 vs 2.20±1.55	2.37±1.33 vs 2.02±1.68	0.115	0.007	0.652
2nd CG site, low vs high
Neuroticism	0.22±0.59 vs 0.14±0.49	0.22±0.52 vs 0.22±0.60	0.066	0.001	0.103
Extraversion	0.12±0.46 vs 0.26±0.63	0.24±0.62 vs 0.21±0.52	0.101	0.001	0.565
Openness to experience	0.14±0.49 vs 0.22±0.59	0.19±0.52 vs 0.25±0.59	0.252	0.001	0.015
Agreeableness	0.12±0.45 vs 0.26±0.64	0.24±0.58 vs 0.21±0.55	0.293	0.007	0.524
Conscientiousness	0.11±0.42 vs 0.28±0.67	0.26±0.64 vs 0.20±0.50	0.09	0.000	0.982
Mean of 1st and 2nd CG site, low vs high
Neuroticism	0.95±0.95 vs 1.30±0.75	0.98±0.79 vs 1.42±0.93	5.509*	0.003	0.026
Extraversion	1.03±0.86 vs 1.28±0.87	1.37±0.94 vs 1.05±0.82	0.095	0.000	2.574
Openness to experience	0.92±0.88 vs 1.38±0.78	1.17±0.97 vs 1.20±0.80	1.747	0.000	1.522
Agreeableness	1.01±0.82 vs 1.32±0.91	1.19±1.04 vs 1.18±0.76	0.715	0.020	0.790
Conscientiousness	1.07±0.81 vs 1.24±0.95	1.30±0.84 vs 1.11±0.91	0.038	0.002	0.989

Notes: The figures on the table show mean±SD of methylation levels of the BDNF gene.

* p<0.05,

** p<0.01.

Abbreviations: BDNF, brain derived neurotrophic factor; NEO PI-R, NEO Personality Inventory-Revised.

Figure 3 Pyrograms of representative individuals with high (A) and low (B) neuroticism scores.

Notes: The percentages of methylation in the highlighted regions are estimated by the ratio of C and T intensities. 1st and 2nd show the 1st and 2nd CG site within the examined region of the BDNF gene, respectively.
Abbreviation: BDNF, brain derived neurotrophic factor.