Association between Neurocognitive Impairment and the Short Allele of the 5-HTT Promoter Polymorphism in Depression: A Pilot Study
Table 1
Distribution of the 5-HTTLPR variants; demographic, clinical, and neuropsychological data for major depressive disorder (MDD) and control groups.
MDD ()
Controls ()
Statistics
value
Effect size (Cohen’s )
5-HTTLPR S/L allele
12/7
13/6
0.732
Gender, female/male
15/4
14/5
0.703
Age, years (range 18–56)
34.8 (12.7)
36.0 (15.8)
0.797
0.08
Education, years
13.4 (2.4)
14.7 (2.8)
0.150
0.50
Duration of illness, years (range)
8.1 (8.0)
—
Number of depressive episodes
2.3 (1.6)
—
Self-ratings:
HDRS
24.0 (3.7)
—
BDI total score, range 0–60
32.6 (11.8)
1.2 (1.6)
<0.001
4.69
BHS total score, range 0–63
12.5 (5.0)
1.9 (0.9)
<0.001
3.59
BAI total score, range 0–20
19.5 (10.6)
1.9 (1.2)
<0.001
2.98
Neuropsychological tests:
Abstract reasoning
Similarities
26.8 (3.7)
27.3 (3.0)
0.700
0.15
Block design
34.5 (7.6)
39.5 (8.6)
0.029
0.62
Episodic memory
Logical memory I
22.3 (8.6)
27.4 (5.4)
0.037
0.73
Logical memory II
19.7 (8.4)
25.0 (4.9)
0.028
0.80
Verbal paired associates I
18.6 (4.7)
20.7 (2.6)
0.089
0.58
Verbal paired associates II
6.8 (1.6)
7.4 (0.9)
0.107
0.48
Visual reproduction I
33.3 (3.7)
38.6 (2.1)
<0.001
1.83
Visual reproduction II
32.5 (5.1)
37.7 (2.9)
<0.001
1.30
Working memory
Visual memory span
18.3 (2.9)
19.6 (2.4)
0.133
0.49
Letter number sequencing
10.5 (2.4)
11.3 (2.0)
0.280
0.36
Executive functioning
Trail making test B sec.
74.1 (21.6)
71.3 (26.9)
0.697
0.12
Stroop color-word sec.
109.5 (21.3)
104.9 (30.2)
0.587
0.18
Semantic fluency
23.2 (6.3)
26.5 (5.1)
0.086
0.58
Letter fluency
16.8 (3.9)
18.3 (3.7)
0.290
0.39
Processing and motor speed
Trail making test A sec.
37.6 (10.8)
31.4 (8.0)
0.026
3.96
Stroop color naming
73.1 (11.7)
63.5 (10.2)
0.012
0.88
Digit symbol (WAIS-R)
57.6 (11.9)
63.5 (12.1)
0.090
0.49
Finger tapping, dominant
47.5 (4.6)
51.1 (6.1)
0.033
0.67
Finger tapping, nondominant
41.7 (5.1)
45.5 (4.4)
0.022
0.80
The results are given as mean (SD), except for gender and 5-HTTLPR variants, for which the results are given as frequency. Group comparisons in neuropsychological tests were analyzed with MANCOVA in which gender and age were covariates. HDRS: Hamilton Rating Scale for Depression; BDI: Beck’s Depression Inventory; BHS: Beck’s Hopelessness Scale; BAI: Beck’s Anxiety Inventory.
