The Brain Derived Neurotrophic Factor and Personality

Table 2

Overview on genetic association studies investigating the BDNF Val66Met polymorphism and personality.

Authors	Participants	Inventory	Results
Arias et al.; [69]	𝑁=937 healthy participants (Castelló/Asturias)	TCI, a part of the sample (𝑛=533) filled in the Big Five questionnaire (BFQ), too.	No main effect of BDNF Val66Met on neuroticism or harm avoidance could be observed. Instead, an interaction effect between BDNF Val66Met and 5-HTTLPR was reported: the seldom Met66Met/ss genotype constellation was associated with highest harm avoidance scores.
De Beaumont et al. [70]	𝑁=132 participants (the study was conducted in Canada; no information on ethnicity available)	NEO-FFI	66Met+ variant was associated with lower extraversion.
Gong et al.; [71]	594 healthy participants (Chinese Han)	EPQ	No main effect of BDNF Val66Met on personality, but extraverted 66Met allele carriers had more problems in shifting their attention away from positive words.
Ham et al.; [72]	𝑁=170 healthy Asian participants (Korean)	TCI	BDNF Val66Met was associated with individual differences in persistence in females. Val66Val and Met66Met significantly differed from each other (direction of effect cannot be reported here, because the article is in Korean language).
Hiio et al.; [73]	Two samples 𝑁=420 healthy participants (Sample 1) and 𝑁=389 healthy participants (Sample 2) (Estonia) investigated together	Estonian personality item pool NEO (Sample 1) and NEO-PI(-R)^1; (Sample 2)	A main effect of BDNF Val66Met on conscientiousness could be observed (the Met66+ variant was associated with lower conscientiousness). Moreover, an interaction effect between BDNF Val66Met and 5-HTTLPR on conscientiousness was observed (Met66+/homozygous ss-carriers were associated with lowest conscientiousness scores).
Hünnerkopf et al. [74]	𝑁=272 healthy participants (Caucasian)	NEO-PI(-R), TPQ	No main effects of BDNF Val66Met on personality were reported. Instead, an interaction effect with genetic variation of the dopamine transporter gene could be observed: carriers of the 66Met+/DAT 9+ genotype constellation were associated with lowest neuroticism scores.
Itoh et al.; [75]	𝑁=151 healthy Asian participant (Japanese)	TCI/NEO-PI-(R)	Female carriers of the Met66Met variant showed higher reward dependence and extraversion scores compared to female 66Val+ carriers. No effects for males could be observed.
Kim et al. [76]	𝑁=391 healthy participants (Korean)	TCI; center for epidemiological studies for depression scale	No main effect of BDNF Val66Met on TCI (or depression) could be observed. An interaction effect could be observed with the variable life stressors: Val66Val carriers under the influence of high recent life stressors showed highest harm avoidance scores.
Jiang et al.; [77]	𝑁=153 healthy participants (mainly Caucasian participants from the general US population)	TPQ	66Met allele was associated with higher harm avoidance scores.
Joffe et al.; [78]	𝑁=467 healthy participants (Caucasian); 𝑛=113 also underwent structural magnetic resonance imaging	NEO-FFI, DASS-21	No significant main effects of BDNF Val66Met on personality or DASS-21 (anxiety, depression, and stress) could be observed. In a subsample the 66Met allele carriers could be characterized by an inverse relationship between neuroticism and hippocampus gray matter volume.
Lang et al.; [79]	𝑁=343 healthy participants (Caucasian)	NEO-FFI, state-trait anxiety inventory	Lower trait anxiety in carriers of the 66Met allele could be observed.
Minelli et al.; [68]	𝑁=217 healthy participants	TCI	No significant association between BDNF Val66Met and personality could be observed.
Montag et al. [80]	𝑁=610 healthy participants (Caucasians)	TCI	Homozygous Met66Met carriers show significantly higher anticipatory worry and fear of uncertainty scores (subscales of harm avoidance).
Montag et al.; [81]	𝑁=768 healthy participants (Caucasians)	TCI	In addition to Montag et al. [80] and in a slightly enlarged sample, carriers of the Met66+/A1+ variant show both lowest novelty seeking and highest harm avoidance scores.
Savitz et al.; [82]	𝑁=241 participants (consisting both of healthy participants and patients suffering from affective disorders; South Africa)	Among others TCI and TEMPS-A	An increasing Met allele dosage effect on hyperthymic temperament (TEMPS-A, HT dimension) but not on TCI scale was reported.
Sen et al.; [83]	𝑁=441 healthy participants (99% non-Hispanic Caucasians)	NEO-PI(-R)	The 66Met allele (especially the homozygous Met66Met genotype) was associated with lower neuroticism scores.
Suzuki et al.; [84]	𝑁=710 healthy participants (Japanese)	TCI, parental bonding instrument	No main effect of BDNF Val66Met on personality could be observed. An interaction effect between genetic variation of BDNF and parental style on personality appeared, which is discussed in Section 5.3.
Terracciano et al. [85]	Two samples (sample called SardiNIA consisted of 𝑁=1560 Italians; the sample called BLSA consisted of 𝑁=1131 participants from mixed ethnicity)	NEO-PI(-R)	The 66Met allele was associated with higher introversion in two samples; moreover, an interaction effect could be observed between BDNF Val66Met and 5-HTTLPR on neuroticism: carriers of the BDNF Val66Val genotype carrying also the LL variant of 5-HTTLPR showed lowest neuroticism scores.
Tochigi et al.; [86]	569 healthy participants (Japanese)	NEO-PI(-R), state-trait anxiety inventory	No association between BDNF Val66Met and personality could be observed.
Tsai et al.; [87]	𝑁=114 healthy participants (Chinese)	TPQ	No association between BDNF Val66Met and personality could be observed.
Walter et al.; [88]	𝑁=664 healthy participants (Caucasians)	Toronto alexithymia scale (TAS-20)	Carriers of the 66Met+/A1+ variant (the latter being an allelic variant of the DRD2/ANKK1 Taq Ia polymorphism) are associated with highest alexithymia scores.
Willis-Owen et al.; [89]	Three samples consisting of 𝑁=4843, 𝑁=571, and 𝑁=516 participants (participants from Southwest-England)	EPQ	No association of BDNF Val66Met with personality could be observed.

The here presented results represent only parts of the results reported in the mentioned studies, because some of the studies focused on aspects beyond BDNF Val66Met and personality.
¹Either the NEO-personality inventory or its revised version was used in the studies of Table 2.