Keywords
Cognition - Neurology - Athletes - Soccer - Brain Injuries, Traumatic
INTRODUCTION
Since the twentieth century, the role of concussion in chronic neurodegenerative disease
has gained attention, while athletes have shown neuropsychiatric symptoms and cognitive
impairment after numerous head impacts throughout their competitive years. Nowadays,
those repeated brain injuries are known as a potential cause of chronic traumatic
encephalopathy (CTE).[1]
In recent years, more attention has been given to subconcussive impacts. The term
“subconcussive” refers to head impacts that could lead to neuronal dysfunction without
causing the typical concussive symptoms of confusion, amnesia, dizziness, visual disturbances,
or headaches.[2] Moreover, the cumulative effects of repetitive minor injury may not manifest for
many years, as in CTE.[3] Therefore, pathological evidence of traumatic brain injury is mixed, and, if detectable,
it is likely to present prior to the onset of overt symptoms or disability.[4]
[5]
Soccer is the most popular sport worldwide, and the only one in which players purposely
and repetitively use their head to hit the ball, on an average of 6 to 12 headings
per competitive game, in which the ball reaches high velocities.[6] Therefore, even though concussive events are not common in soccer, we can consider
that headings may act as subconcussive impacts which, while not causing immediate
symptoms, may contribute to long-term cognitive damage. Moreover, based on field position
and career length, professional soccer players are exposed to a higher risk of developing
neurodegenerative disease, and a more frequent use of dementia-related medications.[7]
[8]
[9] Importantly, the possible negative effects of headings may depend on the rate of
exposure, the time between exposures, and the vulnerability of individual players.[3]
However, to date, research on the possible effects of soccer headings on brain function
has produced controversial results, with some studies[10]
[11]
[12] suggesting an association between heading and cognitive impairment, while others[13]
[14]
[15] have found no correlation.
The current one-year longitudinal case-control study aims to investigate the effects
of soccer headings on cognitive functioning among professional soccer players. We
have previously reported the baseline and cross-sectional results of the study,[16] in which no evidence of cognitive impairment was found among soccer players compared
with non-athletes, and no association between heading exposure and neuropsychological
performance was observed.
METHODS
Two groups of male participants matched by age and years of schooling participated
in the study: 22 active professional soccer players (mean age = 24.1 ± 5.2 years;
mean years of schooling = 11.2 ± 1.7 years) from 2 teams playing in the Brazilian
A-series championship. We also included 37 non-athletes as controls (mean age = 26.1 ± 4.0
years; mean years of schooling = 10.9 ± 1.7 years).
The athlete's group was composed of 5 goalkeepers, 7 defenders, 7 midfielders and
3 forwards. All athletes performed approximately 15 hours of training sessions per
week and usually played one or, during most of the soccer season, two competitive
matches per week.
The control group was composed of non-athletes who worked as doormen or security guards
and who did not practice soccer or practiced it occasionally and at a recreational
level.
To characterize the participants, a sociodemographic questionnaire was applied, as
well as parts of the Mini International Neuropsychiatric Interview (MINI),[17] with the aim of investigating possible psychiatric disorders. None of the participants
showed a major depressive episode or alcohol dependence, nor reported using any psychotropic
drug.
The soccer players were also questioned about the average number of headings per game.
In the cross-sectional analysis of the project of the present research,[16] the number of headings performed by 16 athletes in 42 matches was directly measured
by an observer. Considering this subsample of players, a comparison between the self-reported
and the actual number of headings per game revealed no significant differences. Moreover,
a significant correlation was found between the self-reported and the actual values.[16] Therefore, we believe that the self-report method used in the current study may
be considered a good estimate of headings during official matches.
In relation to previous reports of concussion, 7 players (31.8%) and 4 controls (10.8%)
reported history of concussive impacts (p = 0.045).
A total of six professional players reported regular alcohol use, but none used cigarettes
or other toxic substances. Only one player was on medication affecting the central
nervous system (escitalopram), none had a history of major depressive episodes, and
one soccer player had generalized anxiety disorder. Among the controls, no participant
reported using drugs with effects on the central nervous system, nor exhibited mood
disorder or alcohol dependence. Importantly, no participants from the 2 groups had
consumed alcohol in the 12 hours prior to the neurocognitive tests, and only 1 had
consumed alcohol in the 24 hours leading up to the tests.
The participants were tested on two occasions, T0 and T1, separated by a 1-year interval.
In T0, 7 players and 4 non-athletes referred to a lifetime history of concussion,
with a significant difference in the rate of concussed subjects between groups (p = 0.045). No concussion was reported between T0 and T1 analysis. On both occasions,
the cognitive assessment consisted of 2 parts: the first part lasted ∼ 35 minutes
and was composed of computerized neuropsychological tests designed on the E-Prime
(Psychology Software Tools, Inc., Pittsburgh, PA, United States) software,[18] which measure general motor skills, memory, attention, and executive functioning.
On each test, the reaction time in milliseconds and the percentage of correct responses
were calculated.
Computerized tests
-
Simple Reaction Time Test: the participants press the “1” key in response to a “*”
symbol appearing on the screen at random intervals. The test contains 40 trials in
a single block.
-
Immediate Memory Test: the participants memorize 20 words shown on the screen and
then identify them from sets of 4 words. The test contains 3 blocks of 20 trials.
-
Attention Test: the participants determine whether a target figure appears among four
similar figures. The test includes 60 trials in a single block.
-
Number-Letter test: the participants categorize numbers as odd/even or letters as
consonants/vowels depending on their screen position. The test involves task switching
with 32 trials in 2 blocks and 64 in a third block.
-
Two-Back test: the participants monitor sequences of numbers, pressing “Enter” when
a number matches one from two trials earlier. The test contains 160 trials.
-
Stroop test: the participants identify the ink color of incongruent/congruent words,
with 72 trials in a single block.
-
Delayed memory test: ∼ 30 minutes after the Immediate Memory Test, the participants
indicated whether 40 words were in the original list.
The second part of the cognitive assessment was applied immediately after the first
one, and it involved the Brief Neuropsychological Assessment Battery (NEUPSILIN),[19] which is composed of 32 short tasks that evaluate different cognitive domains such
as time and spatial orientation, attention, perception, memory, arithmetic abilities,
language, praxis, problem solving, and verbal fluency. This part also lasted ∼ 35 minutes,
and the measured variable was the score on each test.
The statistical analyses were performed using the IBM SPSS Statistics for Windows
(IBM Corp., Armonk, NY, United States) software, version 19.0. The normality of each
variable was tested with the Kolmogorov-Smirnov test. For independent samples, mean
comparisons between groups were performed using the Student's t-test for variables with normal distribution, and the Mann-Whitney U-Test, for non-normally
distributed variables. Regarding the dependent samples, the paired Student's t-test was used for variables with normal distribution, and the Wilcoxon test, for
those with non-normal distribution. The correlations involving the athletes' cognitive
performance in T0 and T1 and the self-reported number of headings were calculated
with the Pearson's Correlation Test, controlling for lifetime history of concussion.
The categorical variables were compared using the Chi-squared test. Bonferroni correction
(p < 0.01) was used in the present study to enable multiple comparisons involving cognitive
performance in T0 and T1. In all other analyses, the significance level was set to
5% (p < 0.05).
All subjects provided written informed consent to participate in the study, which
was approved by the Ethics Committee of the Universidade Federal de Minas Gerais (under
CAAE 51433115.1.0000.5149).
RESULTS
In T0 ([Table 1]), the players performed better than the controls in three variables of the computerized
testing, namely reaction time and accuracy in the number-letter test and accuracy
in the two-back test. They also outperformed the controls in terms of memory and arithmetic
abilities in the NEUPSILIN.
Table 1
Cognitive performance of soccer players and controls at T0 and T1
|
Test
|
Variable
|
T0
|
T1
|
|
Players
|
Controls
|
p
|
Players
|
Controls
|
p
|
|
Age
|
Years
|
24.13 ± 5.29
|
26.13 ± 4.09
|
0.110
|
25.32 ± 5.38
|
27.19 ± 4.09
|
0.137
|
|
Schooling
|
Years
|
11.22 ± 1.75
|
10.94 ± 1.74
|
0.888
|
11.34 ± 1.77
|
11.08 ± 1.87
|
0.816
|
|
Computerized tests
|
|
Simple reaction time
|
Reaction time
|
290 ± 28
|
309 ± 39
|
0.047
|
280 ± 21
|
316 ± 37
|
0.000
|
|
Accuracy
|
100.00 ± 0.00
|
99.96 ± 0.20
|
0.441*
|
100 ± 0.00
|
100 ± 0.00
|
−
|
|
Attention
|
Reaction time
|
2,364 ± 580
|
2,725 ± 679
|
0.042
|
2,323 ± 526
|
2,504 ± 579
|
0.235
|
|
Accuracy
|
94.39 ± 4.22
|
94.09 ± 5.23
|
0.823
|
95.83 ± 2.94
|
95.08 ± 3.38
|
0.396
|
|
Immediate memorya
|
Reaction time
|
2,377 ± 565
|
2,935 ± 917
|
0.013
|
2,453 ± 492
|
2,736 ± 768
|
0.128
|
|
Accuracy
|
89.39 ± 7.17
|
86.71 ± 10.55
|
0.296
|
91.36 ± 5.26
|
88.56 ± 8.03
|
0.150
|
|
Number-lettera
|
Reaction time
|
494 ± 137
|
656 ± 231
|
0.004
|
481 ± 116
|
628 ± 197
|
0.056
|
|
Accuracy
|
−1.35 ± 2.78
|
−5.02 ± 6.76
|
0.005
|
−0.28 ± 2.14
|
−1.87 ± 4.10
|
0.001
|
|
Two-back
|
Reaction time
|
518 ± 103
|
561 ± 100
|
0.126
|
503 ± 115
|
564 ± 129
|
0.074
|
|
Accuracy
|
98.66 ± 1.48
|
94.60 ± 4.95
|
0.000
|
98.92 ± 1.51
|
96.37 ± 3.76
|
0.000*
|
|
Stroopa
|
Reaction time
|
172 ± 97
|
163 ± 142
|
0.784
|
115 ± 138
|
126 ± 119
|
0.731
|
|
Accuracy
|
−2.14 ± 2.96
|
−1.95 ± 2.92
|
0.842*
|
−0.76 ± 3.34
|
−1.43 ± 3.18
|
0.842*
|
|
Delayed memory
|
Reaction time
|
874 ± 147
|
1,049 ± 318
|
0.019
|
2,453 ± 492
|
2,736 ± 768
|
0.094
|
|
Accuracy
|
93.75 ± 5.16
|
92.16 ± 7.68
|
0.394
|
91.36 ± 5.26
|
88.56 ± 8.03
|
0.617*
|
|
NEUPSILIN battery
|
|
Time and spatial orientation
|
Score (Total: 8)
|
8.00 ± 0.00
|
7.97 ± 0.16
|
0.441*
|
7.77 ± 0.43
|
7.97 ± 0.16
|
0.441*
|
|
Attention
|
Score (Total: 27)
|
24.31 ± 2.12
|
23.13 ± 1.90
|
0.031
|
24.27 ± 1.69
|
23.76 ± 1.85
|
0.056*
|
|
Perception
|
Score (Total: 12)
|
11.00 ± 1.11
|
11.08 ± 0.92
|
1.000*
|
11.41 ± 0.79
|
11.22 ± 0.75
|
1.000*
|
|
Memory
|
Score (Total: 84)
|
61.72 ± 6.18
|
56.29 ± 7.95
|
0.008
|
64.09 ± 7.07
|
60.05 ± 8.28
|
0.061
|
|
Arithmetic skills
|
Score (total: 8)
|
7.59 ± 0.73
|
6.18 ± 1.94
|
0.002*
|
7.63 ± 0.73
|
6.40 ± 2.06
|
0.002*
|
|
Language
|
Score (total: 53)
|
50.72 ± 1.69
|
49.91 ± 2.34
|
0.164
|
51.31 ± 1.13
|
50.43 ± 1.74
|
0.037
|
|
Praxis
|
Score (total: 22)
|
18.72 ± 1.77
|
17.62 ± 2.13
|
0.046
|
19.18 ± 1.59
|
18.35 ± 2.08
|
0.113
|
|
Problem-Solving
|
Score (total: 2)
|
1.81 ± 0.39
|
1.56 ± 0.55
|
0.073*
|
1.86 ± 0.35
|
1.51 ± 0.55
|
0.073*
|
|
Verbal fluency
|
Score (total: 11)
|
5.36 ± 1.49
|
5.08 ± 1.21
|
0.431
|
5.77 ± 1.44
|
5.14 ± 1.39
|
0.515*
|
Abbreviation: NEUPSILIN, Brief Neuropsychological Assessment Battery.
Notes: The p-values refer to the Student's t-test for independent samples, except those marked with the asterisk (*), which refer
to the Mann-Whitney's U-test. Bold p-values indicate significant differences at a 1% level. In the computerized testing,
the variables measured are the mean reaction time, expressed in milliseconds, and
the mean accuracy, expressed in the percentage of correct answers. In the NEUPSILIN,
the variable measured is the mean score on each test. ªIn the immediate memory, number-letter,
and Stroop tests, reaction time and accuracy are calculated as described in the “Methods”
section.
In T1 ([Table 1]), the players outperformed the controls in three variables of the computerized testing:
reaction time in the general motor skills test and accuracy in the number-letter and
two-back tests. They also showed a better performance in the arithmetic abilities
test from the NEUPSILIN.
Intragroup analyses ([Table 2]) revealed that, while the controls improved their performance in three variables
from T0 to T1 (reaction time in the Attention Test and accuracy in the two-back test,
and score on the NEUPSILIN memory test), no improvement was observed among soccer
players. However, a comparison involving variation in performance between T0 and T1
showed no significant differences between the groups.
Table 2
Variation in cognitive performance of soccer players and controls between T0 and T1
|
Test
|
Variable
|
Players
|
Controls
|
T1-T0
|
|
T0
|
T1
|
p
|
T0
|
T1
|
p
|
Players
|
Controls
|
p
|
|
Computerized tests
|
|
Simple reaction time
|
Reaction time
|
290 ± 28
|
280 ± 21
|
0.025
|
309 ± 39
|
316 ± 37
|
0.213
|
−9.64 ± 18.72
|
6.65 ± 31.86
|
0.033
|
|
Accuracy
|
100.00 ± 0.00
|
100.00 ± 0.00
|
−
|
99.96 ± 0.20
|
100.00 ± 0.00
|
0.317*
|
0.00 ± 0.00
|
0.03 ± 0.20
|
0.441*
|
|
Attention
|
Reaction time
|
2364 ± 580
|
2323 ± 526
|
0.687
|
2725 ± 679
|
2504 ± 579
|
0.003
|
−41.18 ± 472.06
|
−220.57 ± 413.64
|
0.132
|
|
Accuracy
|
94.39 ± 4.22
|
95.83 ± 2.94
|
0.078
|
94.09 ± 5.23
|
95.08 ± 3.37
|
0.256
|
1.43 ± 3.64
|
0.99 ± 5.21
|
0.725
|
|
Immediate memorya
|
Reaction time
|
2377 ± 565
|
2453 ± 492
|
0.546
|
2935 ± 917
|
2736 ± 768
|
0.030
|
76.36 ± 583.28
|
−199.30 ± 534.69
|
0.069
|
|
Accuracy
|
89.39 ± 7.17
|
91.35 ± 5.26
|
0.176
|
86.71 ± 10.55
|
88.55 ± 8.03
|
0.172
|
1.96 ± 6.58
|
1.84 ± 8.04
|
0.952
|
|
Number-lettera
|
Reaction time
|
494 ± 137
|
481 ± 116
|
0.608
|
656 ± 231
|
628 ± 197
|
0.406
|
−13.55 ± 121.85
|
−27.43 ± 198.39
|
0.740
|
|
Accuracy
|
−1.35 ± 2.78
|
−0.28 ± 2.14
|
0.239
|
−5.02 ± 6.76
|
−1.87 ± 4.10
|
0.013
|
1.06 ± 4.13
|
3.15 ± 7.32
|
0.226
|
|
Two-back
|
Reaction time
|
518 ± 103
|
503 ± 115
|
0.352
|
561 ± 100
|
564 ± 129
|
0.783
|
−15.14 ± 74.55
|
3.32 ± 72.72
|
0.354
|
|
Accuracy
|
98.66 ± 1.48
|
98.91 ± 1.50
|
0.511*
|
94.60 ± 4.95
|
96.36 ± 3.75
|
0.003
|
0.25 ± 1.67
|
1.75 ± 3.39
|
0.058
|
|
Stroopa
|
Reaction time
|
175 ± 97
|
115 ± 138
|
0.053
|
163 ± 142
|
126 ± 119
|
0.120
|
−57.41 ± 131.47
|
−36.16 ± 138.20
|
0.563
|
|
Accuracy
|
−2.14 ± 2.96
|
−0.75 ± 3.34
|
0.155*
|
−1.95 ± 2.92
|
−1.42 ± 3.18
|
0.420*
|
1.39 ± 4.26
|
0.52 ± 4.13
|
0.446
|
|
Delayed memory
|
Reaction time
|
874 ± 147
|
888 ± 170
|
0.605
|
1049 ± 318
|
990 ± 249
|
0.057
|
13.82 ± 123.38
|
−58.14 ± 179.57
|
0.103
|
|
Accuracy
|
93.75 ± 5.16
|
96.47 ± 3.59
|
0.029
|
92.16 ± 7.68
|
92.97 ± 7.72
|
0.486*
|
2.72 ± 5.45
|
0.81 ± 7.04
|
0.278
|
|
NEUPSILIN
|
|
Time and spatial orientation
|
Score (total: 8)
|
8.00 ± 0.00
|
7.77 ± 0.42
|
0.025*
|
7.97 ± 0.16
|
7.97 ± 0.16
|
1.000*
|
−0.22 ± 0.42
|
0.00 ± 0.23
|
0.012*
|
|
Attention
|
Score (total: 27)
|
24.31 ± 2.12
|
24.27 ± 1.69
|
0.935
|
23.13 ± 1.90
|
23.75 ± 1.84
|
0.167*
|
−0.04 ± 2.57
|
0.72 ± 2.34
|
0.315*
|
|
Perception
|
Score (total: 12)
|
11.00 ± 1.11
|
11.40 ± 0.79
|
0.117*
|
11.08 ± 0.92
|
11.21 ± 0.75
|
0.415*
|
0.40 ± 1.25
|
0.18 ± 1.04
|
0.290*
|
|
Memory
|
Score (total: 84)
|
61.72 ± 6.18
|
64.09 ± 7.07
|
0.069
|
56.29 ± 7.95
|
60.05 ± 8.27
|
0.002
|
2.36 ± 5.78
|
3.89 ± 6.89
|
0.387
|
|
Arithmetic skills
|
Score (total: 8)
|
7.59 ± 0.73
|
7.63 ± 0.72
|
0.860*
|
6.18 ± 1.94
|
6.40 ± 2.06
|
0.471*
|
0.04 ± 0.78
|
0.27 ± 1.78
|
0.717*
|
|
Language
|
Score (total: 53)
|
50.72 ± 1.69
|
51.31 ± 1.12
|
0.034
|
49.91 ± 2.34
|
50.43 ± 1.74
|
0.100
|
0.59 ± 1.22
|
0.59 ± 1.83
|
0.993
|
|
Praxis
|
Score (total: 22)
|
18.72 ± 1.77
|
19.18 ± 1.59
|
0.226
|
17.62 ± 2.13
|
18.35 ± 2.08
|
0.011
|
0.45 ± 1.71
|
0.94 ± 1.91
|
0.326
|
|
Problem-Solving
|
Score (total: 2)
|
1.81 ± 0.39
|
1.86 ± 0.35
|
0.655*
|
1.56 ± 0.55
|
1.51 ± 0.55
|
0.414*
|
0.04 ± 0.48
|
−0.05 ± 0.40
|
0.399*
|
|
Verbal fluency
|
Score (total: 11)
|
5.36 ± 1.49
|
5.77 ± 1.44
|
0.215
|
5.08 ± 1.21
|
5.13 ± 1.39
|
0.777
|
0.40 ± 1.50
|
0.08 ± 1.21
|
0.362
|
Abbreviation: NEUPSILIN, Brief Neuropsychological Assessment Battery.
Notes: Soccer players and controls at T0 and T1: the p-values refer to the paired t-test, except those marked with the asterisk (*), which refer to the Wilcoxon test.
Soccer players and controls at T1-T0: the p-values refer to the Student's t-test for independent samples, except those marked with the asterisk (*), which refer
to the Mann-Whitney's U-test. Bold p-values indicate significant differences at a 1% level. In the computerized testing,
the variables measured are the mean reaction time, expressed in milliseconds, and
the mean accuracy, expressed in the percentage of correct answers. In the NEUPSILIN,
the variable measured is the mean score on each test. ªIn the immediate memory, number-letter,
and Stroop tests, reaction time and accuracy are calculated as described in the “Methods”
section.
Among soccer players ([Table 3]), no significant correlations were found between the self-reported number of headings
per game and cognitive performance in T0 nor T1, controlling for concussion history.
Table 3
Correlations between cognitive performance of soccer players and self-report of headings
per game
|
Test
|
Variable
|
Correlation coefficient (T0)
|
p
|
Correlation coefficient (T1)
|
p
|
|
Computerized tests
|
|
Simple reaction timea
|
Reaction time
|
0.005
|
0.983
|
0.039
|
0.868
|
|
Accuracy
|
−
|
−
|
−
|
−
|
|
Attention
|
Reaction time
|
−0.398
|
0.074
|
−0.188
|
0.415
|
|
Accuracy
|
0.178
|
0.439
|
−0.130
|
0.574
|
|
Immediate memoryb
|
Reaction time
|
−0.208
|
0.366
|
−0.264
|
0.247
|
|
Accuracy
|
0.138
|
0.551
|
0.194
|
0.401
|
|
Number-letterb
|
Reaction time
|
0.144
|
0.533
|
−0.156
|
0.500
|
|
Accuracy
|
−0.217
|
0.345
|
0.327
|
0.148
|
|
Two-back
|
Reaction time
|
0.125
|
0.589
|
−0.160
|
0.488
|
|
Accuracy
|
−0.006
|
0.981
|
0.049
|
0.832
|
|
Stroopb
|
Reaction time
|
−0.160
|
0.489
|
0.084
|
0.718
|
|
Accuracy
|
0.288
|
0.205
|
0.243
|
0.287
|
|
Delayed memory
|
Reaction time
|
−0.065
|
0.780
|
−0.298
|
0.189
|
|
Accuracy
|
0.105
|
0.650
|
−0.081
|
0.726
|
|
NEUPSILIN battery
|
|
Time and spatial orientationa
|
Score
|
−
|
−
|
0.085
|
0.714
|
|
Attention
|
Score
|
−0.409
|
0.066
|
0.133
|
0.566
|
|
Perception
|
Score
|
0.179
|
0.437
|
−0.106
|
0.648
|
|
Memory
|
Score
|
−0.263
|
0.250
|
−0.063
|
0.785
|
|
Arithmetic skills
|
Score
|
0.103
|
0.657
|
0.405
|
0.069
|
|
Language
|
Score
|
0.059
|
0.800
|
0.208
|
0.367
|
|
Praxis
|
Score
|
0.228
|
0.321
|
0.117
|
0.613
|
|
Problem-Solving
|
Score
|
0.320
|
0.157
|
0.172
|
0.456
|
|
Verbal fluency
|
Score
|
−0.112
|
0.628
|
0.105
|
0.652
|
Abbreviation: NEUPSILIN, Brief Neuropsychological Assessment Battery.
Notes: The correlations were measured through the Pearson's correlation test, controlling
for the variable “lifetime history of concussion.” aCorrelation tests were not performed for accuracy in the simple reaction time test
at T0 and T1 and for score in the time and spatial orientation test at T0, since all
subjects had 100% of correct responses and achieved the maximum score respectively.
bIn the immediate memory, number-letter, and Stroop tests, reaction time and accuracy
are calculated as described in the “Methods” section.
DISCUSSION
The inconclusive findings on the effects of headings on cognitive impairment among
soccer players underscore the need for more robust data on this topic.[20] In the present study, professional soccer players performed better than controls
in neuropsychological tests that require task-switching and working-memory abilities,
as well as in general motor skills, memory, and arithmetic skills. We believe that
this may be related to team sport practice, which demands strategic decision-making
in complex and quickly changing contexts. Besides, there is evidence that participation
in sports relates to faster processing speed in measures of simple reaction time.[21] This can explain the advantage of professional soccer players in reaction-time measures
in T0 (number-letter test) and T1 (general motor skills test).
The present study shows no evidence of impairment in the cognitive functioning of
professional soccer players. In fact, athletes displayed shorter reaction times and
greater accuracy in some computerized tests, as well as better results in memory and
arithmetic skills of the NEUPSILIN. This may be explained by the improvement in motor
skills and ability to develop a strategy that comes from sports practice. However,
the longitudinal analysis of the participants draws attention. Although there was
no setback in the athletes' performance, they showed a less expressive learning curve
than the control group.
The relationship between soccer practice and brain function remains controversial,
and further studies involving larger samples and longer follow-up are needed to achieve
a better understanding of the effects of subconcussive impacts on brain function.
One strength of the present study is the participation of active high-level professional
soccer players, since most studies addressing the effects of soccer headings on cognition
have not investigated this population. Thus, in the current study, we analyzed individuals
who are constantly exposed to many head impacts.
Nevertheless, we must acknowledge that the present study has limitations, such as
the fact that soccer players were compared with non-athletes, which is not an ideal
comparison group, given the well-established cognitive benefits of physical activity.[22] Hence, physical activity could act as a confounding variable and compromise the
study analysis. Moreover, only headings during competitive matches were considered
in the study, excluding the training sessions, and possibly underestimating the number
of subconcussive impacts. This may have had an influence on our results, which showed
no significant differences between soccer players who reported a greater or smaller
number of headings per game. Another limitation is that the number of headings was
estimated through self-report by the soccer players, which is potentially biased or
imprecise. History of concussion was also more frequent among players than controls.
Finally, the sample size was small, but this was related to the number of players
who agreed to participate and who were available for both the baseline and the one-year
evaluations.
In conclusion, the soccer players evaluated in the present study did not show signs
of cognitive impairment and actually outperformed the controls in certain tests. However,
given the body of evidence linking professional soccer activity with later-life dementia,
efforts to optimize head trauma prevention for soccer players need to be considered
to reduce long-term risks.[23]
Bibliographical Record
Giovanni Batista Palma, Mariana Drummond Martins Lima, Ana Carolina Oliveira Rodrigues,
Clarisse Vasconcelos Friedlaender, Celso Furtado de Azevedo Filho, Rodrigo Campos
Pace Lasmar, Paulo Caramelli. Cognitive functioning and soccer heading: one-year longitudinal
assessment among professional players. Arq Neuropsiquiatr 2025; 83: s00451805051.
DOI: 10.1055/s-0045-1805051
