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Research Article

BDNF as a potential predictive biomarker for patients with pediatric cerebral palsy

[version 1; peer review: 1 approved with reservations]
PUBLISHED 18 Nov 2022
Author details Author details
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Abstract

Background: Cerebral palsy (CP) is the most common motor disability in children, which is instigated by damage to the developing brain that affects the ability to control the muscles. The main types of CP are spastic CP, dyskinesia CP and mixed CP. The aim of this work was to estimate the concentrations of complete blood count (CBC), erythrocytic sedimentation rate (ESR), C-reactive protein (CRP), brain-derived neurotrophic factor (BDNF), and tumor necrosis factor-α (TNF-α) in children with CP compared to the control group.
Methods: A total of 75 Egyptian children were enrolled in this study, 45 had CP and 30 were controls. CBC, ESR, CRP, BDNF, and TNF-α were assessed.
Results: The ESR, CRP and TNF-α levels showed statistically significant increases in cases compared with controls. While the neutrophil/lymphocyte ratio and the BDNF levels were significantly lower in CP compared with the controls. When comparing the different groups of CP with each other; there were no significant differences. Regarding the correlation of BDNF and different studied parameters, our study showed a positive correlation between BDNF and TNF levels only within the group with spastic CP.
Conclusions: BDNF may be considered as a biomarker or treatment target for CP to avoid further complications as still there is insufficient progress in the prediction, early diagnosis, treatment, and prevention of CP. Furthermore, searching for novel strategies to increase BDNF levels may open a new opportunity for the treatment of CP.

Keywords

Cerebral palsy, BDNF, TNF-α, ESR, CRP

Introduction

Cerebral palsy (CP) is one of the most obvious forms of physical incapacity in childhood; with an estimated worldwide pervasiveness of around 1.5–3 per 1,000.1 CP is a wide umbrella term that covers lesions of the developing brain causing diminished movement and may affect perceptual and even cognitive problems.2 CP is usually confined to a group of disorders affecting posture and movement, causing limitation of activity and non-progressive turbulences, which usually happens during infant or fetal brain development. It was first termed ‘cerebro-spinal disorder’, and soon transitioned to the term cerebral palsy.3 However, in spite of the change in the clinical diagnosis of CP, the definition continued to focus on the brain without stressing the developmental spinal cord dysfunction.4

In regard to clinical overview, it begins in early childhood and persists throughout the individuals lifetime.2 Children with CP might develop a variety of secondary complications over time that will impact their functional capabilities showing huge variation from one another.5 Complications may include feeding difficulties; pain; fractures; osteoporosis; communication difficulties; drooling; spasticity and contractures; osteopenia; and functional gastrointestinal abnormalities, vomiting, and constipation.6 The associated intellectual impairment in children with CP needs more recognition,7 as intellectual disability is an important and relatively common issue that influences daily activities, the burden of care, and of course quality of life.8

The etiology of CP is complicated. For more than 100 years, it was speculated that the majority of CP cases were related to infant brain hypoxia in the perinatal period or during labor, which made CP incidence a matter of obstetric and neonatal care quality. CP is a result of heterogeneous risk factors complementary to specific etiology giving a wide variation in associated secondary conditions, functional limitations, severity, clinical features, and evolution of the condition over the lifetime of the person.9 One of the most highlighted risk factors is premature birth, especially before 28 weeks of gestation, which has become one of the most associated risk factors for the development of CP.10 It has long been thought that CP is caused by environmental triggers, recent findings identified rare mutations in single genes that may be the cause of this disorder.11 However, despite all the medical care done in these areas, CP incidence has remained unchanged.12

Surveillance of Cerebral Palsy in Europe (SCPE), aiming to standardize CP classification has suggested a simple classification for patients, dividing them into three chief groups: ataxic, dyskinetic (choreoathetosis & dystonia), spastic (unilateral or bilateral spastic).13 While mixed type is a combination of the aforementioned types. Another classification rendering to data from the Gross Motor Function Classification System (GMFCS): level 1, the patients are able to walk freely; level 2, patients walk with certain (slight) limitations on their own; level 3, patients walk by ancillary apparatus; level 4, patients could move on their own, but within specific limits, she/he could use an electrical wheelchair; level 5, patients are not capable to move on their own in a wheelchair.14

As for the diagnosis of CP, it is fundamentally based on clinical findings. Early diagnosis is usually based on using standardized neuromotor assessment, findings on magnetic resonance imaging (MRI), and clinical history, moreover, in the greatest clinical settings, CP can only be diagnosed with confidence by the age of 2 years old.15

Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophins (NTs), a family of proteins that support the function of the central nervous system (CNS), and it was recognized in 1982, as a small dimeric protein.16 There are two main types of BDNF present in the human body, pro- and mature BDNF.17 NTs are synthesized mainly in the CNS.18 BDNF plays a crucial part in the development of the nervous system by acting on neuronal development, growth and survival, neurogenesis, cell differentiation, synaptic plasticity and synaptogenesis.19 BDNF is expressed widely in the brain, comprising the hippocampus, cortex, and basal forebrain regions. It crosses the blood-brain barrier in a bi-directional mode and can therefore be detected in the blood.20 Pro-BDNF promotes neuronal cell death whereas mature BDNF stimulates neuronal cell survival and growth.21 Differentiating between the BDNF forms has been well-known as one of the significant factors skewing reliable BDNF measurements, causing contradictory findings.22 Along with the nervous system, BDNF is also found peripherally in the skeletal muscle, lungs smooth muscle cells and heart. The chief reservoir of this protein within the peripheral blood are platelets.23

Furthermore, the maximum concentrations of pro-BDNF are detected perinatally, following which it diminishes with age, while in adulthood it remains detectable at very low levels. These data justify partially that the brains of infants and newborns are more fragile to ischemia owing to lack of sufficient mature BDNF in the CNS and low-frequency neuronal activities.24

We aimed to assess the circulating concentrations of BDNF, TNF-α, and other blood parameters in children with CP compared with the control group. We then further subdivided CP groups according to clinical neurological affection into spastic, dyskinesia, and mixed groups, comparing the different biomarkers, including the blood level of BDNF, tumor necrosis factor-α (TNF-α), and other parameters with the control group.

Methods

Ethics approval and consent

The goal of the study was clarified to the guardians of all participants. Written informed consent was obtained from all the parents of the children before they were enrolled in this study, which was permitted by the Ethical Committee, Faculty of Medicine, Delta University of Science and Technology, Egypt (FM2108007) in July 2021.

Participants

A total of 75 Egyptian children were enrolled from October 2021 to March 2022; CP was confirmed by clinical symptoms assessed by a neurological pediatrician. The CP children were enrolled as they were seeking physical therapy and follow up with pediatric clinicians. A total of 45 children with CP and 30 controls were enrolled; and they were matched by age, sex and socioeconomic status. The ages varied from 2 to 7 years old (mean age of controls: 3.9 ± 1.5, mean age of cases: 4.3 ± 1.5). As for control participants, they were selected by pediatric clinicians to be eligible for our study. They were enrolled following physical examination if they were determined to not show any symptoms or signs of active infection or chronic disease.

Participants were classified into two main groups. Group І comprised the controls, Group II included the participants with CP, which was further divided into three groups, spastic CP (26 patients), dyskinesia CP (12 patients) and mixed CP (seven patients) (Physiopedia).25

Study design

Exclusion criteria of the CP patients and healthy volunteers included neurological, inflammatory, endocrine, cardiovascular, hepatic, renal or any clinically significant chronic disease and immunocompromised subjects. To all participants the following were done:

  • 1. Detailed history taking: detailed history was taken from all participants including starting of showing any delayed milestones.

  • 2. Complete physical examination: complete physical examination was done for all groups.

  • 3. Anthropometric measurements: namely body weight, height measurements.

  • 4. Biochemical assessments

Biochemical assessments

Assessment of liver function

Liver function enzyme alanine aminotransferase (ALT) was estimated using fully automated chemistry analyzer Cobas-C and Cobas.26

Assessment of C-reactive protein (CRP)

CRP was assessed using a fully automated Nephelometric quantitative technique, which is more specific than Latex. The analyzer includes a dilutor with temperature controlled (37°C) transfer arms; reagent, sample, standards rack stations (with barcode reading); buffer compartment; dilution racks; temperature controlled (37°C) cuvette rotor; cuvette washing device; bar code wand reader; and optical system.27

Assessment of erythrocytic sedimentation rate (ESR)

Using the Westergren method, which measures the distance (in millimeters) that red blood cells in anticoagulated whole blood fall to the bottom of a standardized, upright, elongated tube due to gravity over one hour, ERS was determined.28

Complete blood count (CBC)

CBC was analyzed using an automated blood cell counter (XE 2100). Haemoglobin; HBG, Neutrophil/lymphocyte ratio (NLR) was evaluated as the absolute neutrophil count divided by the absolute lymphocyte count, while the platelet lymphocyte ratio (PLR) was calculated by platelet count divided by absolute lymphocyte count.29

Quantification of TNF-α

TNF-α levels in serum was measured using a Human TNF alpha ELISA Kit (Abcam Cat# ab181421, RRID:AB_2924775).

Quantification of BDNF

BDNF levels in serum were measured using a Human BDNF ELISA Kit (Abcam Cat# ab212166, RRID:AB_2924770).

Both ELISA tests were done according to the manufacturer’s instructions. The full protocol can be found at protocols.io.

Sample number

Assuming that the confidence interval (CI) = 95% and the error = 5%, a cross-sectional study based on the previous situation in literature, was 8% among children (5–15 years old). Knowing that the average incidence of CP is estimated to range between 1.5 and 3.0 per 1,000 live births in Dakahalia, the estimated sample size to achieve 95% confidence and avoid α error, was calculated (Calculator.net).

Statistical analysis of the data

Data were analyzed using IBM SPSS Statistics (RRID:SCR_016479) software package version 20.0 (Armonk, NY: IBM Corp). Checking for normality was performed by the Shapiro-Wilk test. Quantitative data were expressed as a range from minimum to maximum, mean, standard deviation, and median. For normally distributed quantitative variables, Student t-test was used to compare two groups, while one-way ANOVA test was used for comparing the four studied groups and followed by a post hoc test (Tukey) for pairwise comparison. The significance of the obtained results was judged at the 5% level. A Pearson correlation coefficient was performed between BDNF and TNF with different parameters.

Results

A total of 75 subjects were involved in our work (Table 1).45 Their age ranged from 2 to 7 years old. A total of 35 patients were male (46.6%), and 40 were female (53.3%). No significant differences between the control group and patients regarding age, sex, weight, and ALT were found (Table 1).

Table 1. Comparison between the two studied groups according to demographic data and laboratory investigation.

ParameterControl (n = 30)Cases (n = 45)p-value
Age (years)
Mean ± SD.3.9 ± 1.54.3 ± 1.50.280
Median (Min. – Max.)3.5 (2 – 7)4 (2 – 7)
Sex
Male15 (50%)20 (44.4%)0.637
Female15 (50%)25 (55.6%)
Weight (kg)
Mean ± SD.18.4 ± 2.318.5 ± 2.60.849
Median (Min. – Max.)18.5 (14 – 23)19 (13 – 24)
ALT (U/L)
Mean ± SD.20.1 ± 4.819.6 ± 4.60.674
Median (Min. – Max.)19 (12 – 29)19 (13 – 29)
CRP (mg/l)
Mean ± SD.1.7 ± 0.310.9 ± 2.6<0.001*
Median (Min. – Max.)1.7 (1.2 – 2.2)10 (8 – 19)
TNF (pg/ml)
Mean ± SD.16.4 ± 1.228 ± 3.6<0.001*
Median (Min. – Max.)16 (15 – 18)28 (14 – 34)
ESR (mm/hr)
Mean ± SD.7.9 ± 1.527.2 ± 3.9<0.001*
Median (Min. – Max.)8 (5 – 10)27 (20 – 35)
HBG g/dl
Mean ± SD.11.1 ± 0.612 ± 0.9<0.001*
Median (Min. – Max.)11 (10.3 – 12.8)11.9 (10.5 – 13.5)
WBCs (103/ul)
Mean ± SD.6865.3 ± 728.14981.1 ± 494.3<0.001*
Median (Min. – Max.)6875 (4590 – 7900)5100 (4150 – 5790)
BDNF (pg/ml)
Mean ± SD.30.7 ± 4.214.1 ± 2.5<0.001*
Median (Min. – Max.)30 (23 – 38)13 (10 – 18)

* Statistically significant at p ≤ 0.05. ALT, alanine aminotransferase; CRP, C-reactive protein; TNF, tumor necrosis factor; ESR, erythrocytic sedimentation rate; HBG, hemoglobin; WBCs, white blood cells; BDNF, brain-derived neurotrophic factor.

The ESR, CBC, hemoglobin, lymphocyte, and NLR showed a statistically significant difference between the control group and cases (Table 2).

Table 2. Comparison between the two studied groups according to CBC.

ParameterControl (n = 30)Cases (n = 45)p-value
Neutrophils (103/ul)
Mean ± SD.4,245.5 ± 434.82,654.8 ± 244.1<0.001*
Median (Min. – Max.)4,180 (2,988 – 4,988)2,670 (2,250 – 3,090)
Neutrophils, %
Mean ± SD.61.9 ± 2.153.4 ± 2<0.001*
Median (Min. – Max.)62 (58 – 65)53 (50 – 58)
Lymphocytes (103/ul)
Mean ± SD.2,619.8 ± 344.42,326.3 ± 282.3<0.001*
Median (Min. – Max.)2,750 (1,602 – 3,150)2,400 (1,790 – 2,900)
Lymphocytes, %
Mean ± SD.38.1 ± 2.146.6 ± 2<0.001*
Median (Min. – Max.)38 (35 – 42)47 (42 – 50)
Neutrophils/Lymphocytes
Mean ± SD.1.6 ± 0.21.1 ± 0.1<0.001*
Median (Min. – Max.)1.6 (1.4 – 1.9)1.1 (1 – 1.4)

* Statistically significant at p ≤ 0.05. CBC, complete blood count.

BDNF levels in the CP group (14.1 ± 2.5 (pg/ml)) were significantly lower (P < 0.001) than those of controls (30.7 ± 4.2 (pg/ml)). When comparing the different groups of CP with each other; there were no significant differences. On the other hand, comparing each subtype of CP with the control group showed a significantly higher value for the control group (P < 0.001) (Tables 3 and 4).

Table 3. Comparison between the four studied groups according to demographic data and laboratory investigation.

ParameterControl (n = 30)Cases (n = 45)p-value
Spastic (n = 26)Dyskinesia (n = 12)Mixed (n = 7)
Age (years)
Mean ± SD.3.9 ± 1.54.1 ± 1.64.8 ± 1.74.1 ± 1.10.449
Median (Min. – Max.)3.5 (2 – 7)4 (2 – 7)5 (2 – 7)4 (3 – 6)
Sex
Male15 (50%)13 (50%)5 (41.7%)2 (28.6%)MCp= 0.779
Female15 (50%)13 (50%)7 (58.3%)5 (71.4%)
Weight (kg)
Mean ± SD.18.4 ± 2.317.7 ± 2.819.6 ± 1.919.6 ± 1.90.098
Median (Min. – Max.)18.5 (14 – 23)17.5 (13 – 24)19.5 (17 – 22)19 (17 – 22)
ALT (U/L)
Mean ± SD.20.1 ± 4.820.8 ± 5.118.1 ± 2.317.9 ± 50.256
Median (Min. – Max.)19 (12 – 29)20 (13 – 29)18.5 (14 – 22)18 (13 – 25)
CRP (mg/l)
Mean ± SD.1.7 ± 0.311 ± 3.210.7 ± 1.610.6 ± 1.7<0.001*
Median (Min. – Max.)1.7 (1.2 – 2.2)10 (8 – 19)11 (8 – 14)11 (8 – 13)
p0<0.001*<0.001*<0.001*
Sig. bet. grps.p1 = 0.953,
p2 = 0.949,
p3 = 1.000
TNF (pg/ml)
Mean ± SD.16.4 ± 1.226 ± 2.832.5 ± 128 ± 0.8<0.001*
Median (Min. – Max.)16 (15 – 18)26.5 (14 – 29)32.5 (31 – 34)28 (27 – 29)
p0<0.001*<0.001*<0.001*
Sig. bet. grps.p1 < 0.001*,
p2 = 0.064,
p3 < 0.001*
ESR (mm/hr)
Mean ± SD.7.9 ± 1.528.2 ± 3.925.3 ± 3.427 ± 3.7<0.001*
Median (Min. – Max.)8 (5 – 10)29 (20 – 35)25.5 (20 – 30)27 (22 – 33)
p0<0.001*<0.001*<0.001*
Sig. bet. grps.p1 = 0.039*,
p2 = 0.810,
p3 = 0.623
HBG (g/dl)
Mean ± SD.11.1 ± 0.612 ± 0.812 ± 111.7 ± 0.9<0.001*
Median (Min. – Max.)11 (10.3 – 12.8)12 (10.5 – 13.5)11.9 (10.5 – 13.5)11.8 (10.5 – 12.9)
p0<0.001*0.008*0.248
Sig. bet. grps.p1 = 0.999,
p2 = 0.792,
p3 = 0.892
WBCs (103/ul)
Mean ± SD.6,865.3 ± 728.15,047.3 ± 512.64,951.7 ± 455.94,785.7 ± 500.3<0.001*
Median (Min. – Max.)6,875 (4,590 – 7,900)5,100 (4,230 – 5,790)5,160 (4,200 – 5,500)4,700 (4,150 – 5,350)
p0<0.001*<0.001*<0.001*
Sig. bet. grps.p1 = 0.968,
p2 = 0.738,
p3 = 0.938
BDNF (pg/ml)
Mean ± SD.30.7 ± 4.214.8 ± 2.513.6 ± 2.712.3 ± 0.8<0.001*
Median (Min. – Max.)30 (23 – 38)14 (10 – 18)12.5 (11 – 18)12 (11 – 13)
p0<0.001*<0.001*<0.001*
Sig. bet. grps.p1 = 0.703,
p2 = 0.271,
p3 = 0.835

* Statistically significant at p ≤ 0.05. ALT, alanine aminotransferase; CRP, C-reactive protein; TNF, tumor necrosis factor; ESR, erythrocytic sedimentation rate; HBG, hemoglobin; WBCs, white blood cells; BDNF, brain-derived neurotrophic factor.

Table 4. Comparison between the four studied groups according to CBC.

ParameterControl (n = 30)Cases (n = 45)
Spastic (n = 26)Dyskinesia (n = 12)Mixed (n = 7)p-value
Neutrophils (103/ul)
Mean ± SD.4,245.5 ± 434.82,674.2 ± 257.72,675 ± 1992,548 ± 268.2<0.001*
Median (Min. – Max.)4,180 (2,988 – 4,988)2,655 (2,250 – 3,090)2,760 (2,290 – 2,950)2,450 (2,280 – 2,980)
p0<0.001*<0.001*<0.001*
Sig. bet. grps.p1 = 1.000,
p2 = 0.814,
p3 = 0.856
Neutrophils, %
Mean ± SD.61.9 ± 2.153.1 ± 254.1 ± 253.1 ± 2<0.001*
Median (Min. – Max.)62 (58 – 65)53 (50 – 58)54 (51 – 58)52 (51 – 56)
p0<0.001*<0.001*<0.001*
Sig. bet. grps.p1 = 0.495,
p2 = 1.000,
p3 = 0.767
Lymphocytes (103/ul)
Mean ± SD.2,619.8 ± 344.42,373.1 ± 288.42,276.7 ± 279.62,237.7 ± 265.90.001*
Median (Min. – Max.)2,750 (1,602 – 3,150)2,435 (1,790 – 2,900)2,390 (1,900 – 2,700)2,250 (1,840 – 2,564)
p00.020*0.009*0.022*
Sig. bet. grps.p1 = 0.809,
p2 = 0.734,
p3 = 0.993
Lymphocytes, %
Mean ± SD.38.1 ± 2.146.9 ± 245.9 ± 246.9 ± 2<0.001*
Median (Min. – Max.)38 (35 – 42)47 (42 – 50)46 (42 – 49)48 (44 – 49)
p0<0.001*<0.001*<0.001*
Sig. bet. grps.p1 = 0.495,
p2 = 1.000,
p3 = 0.767
Neutrophils/Lymphocytes
Mean ± SD.1.6 ± 0.21.1 ± 0.11.2 ± 0.11.2 ± 0.1<0.001*
Median (Min. – Max.)1.6 (1.4 – 1.9)1.1 (1 – 1.4)1.2 (1 – 1.4)1.1 (1.1 – 1.3)
p0<0.001*<0.001*<0.001*
Sig. bet. grps.p1 = 0.390,
p2 = 0.697,
p3 = 0.778

* Statistically significant at p ≤ 0.05. CBC, complete blood count.

The TNF level in the CP group (28 ± 3 (pg/ml)) was significantly higher (P < 0.001), than those of the control group (16.4 ± 1.2 (pg/ml)). When comparing the different groups of CP with each other; there was a significant difference between the group with Spastic CP (26 ± 2.8 (pg/ml)) and dyskinesia (32.5 ± 1 (pg/ml)) (P < 0.001). Moreover, when comparing Dyskinesia CP (32.5 ± 1 (pg/ml)) and mixed CP (28 ± 0.8 (pg/ml)) there was a significant difference (P < 0.001), with higher levels found in the Dyskinesia group. On the other hand, comparing spastic CP and dyskinesia CP showed no significant difference (p2 = 0.064) (Tables 3 and 4).

Furthermore, the CRP level was significantly higher in the CP group (10.9 ± 2.60 (mg/l)), than those of the control group (1.7 ± 0.3 (mg/l)) (P < 0.001). While comparing the different groups of CP with each other; there was no significant difference. On the other hand, comparing each subtype of CP with the control; it showed a significantly higher value for the control group (P < 0.001) (Tables 3 and 4).

Also, the NLR was significantly lower in the CP group (1.1 ± 0.1), than those of the control group (1.6 ± 0.2) (P < 0.001). When comparing the different groups of CP with each other; there was no significant difference. On the other hand, comparing each subtype of CP with the control; it showed a significantly higher value for the control group (P < 0.001) (Tables 2 and 4).

With regard to the correlation of BDNF with the various studied parameters, our study only showed a positive correlation between BDNF and TNF levels with spastic CP (Table 5), otherwise there were no significant correlations with other parameters (Table 6).

Table 5. Correlation between BDNF with different parameters.

BDNF (pg/ml) vs.Control (n = 30)Cases (n = 45)Spastic (n = 26)Dyskinesia (n = 12)Mixed (n = 7)
rprprprprp
CRP (mg/l)0.2100.265-0.1700.263-0.2410.236-0.2420.4480.2380.607
Neutrophils0.1650.383-0.1060.487-0.2020.323-0.0720.825-0.6510.113
Lymphocytes0.0070.972-0.1220.426-0.3080.1260.0100.975-0.5300.221
N/L ratio0.2080.271-0.0150.9230.1890.356-0.1670.604-0.2580.576
TNF (pg/ml)0.0020.9920.0150.9230.3980.044*0.0500.8770.0001.000

* Statistically significant at p ≤ 0.05. BDNF, brain-derived neurotrophic factor; CRP, C-reactive protein; TNF, tumor necrosis factor.

Table 6. Correlation between TNF with different parameters.

TNF vs.Control (n = 30)Cases (n = 45)Spastic (n = 26)Dyskinesia (n = 12)Mixed (n = 7)
rprprprprp
CRP (mg/l)0.0380.840-0.1940.201-0.3220.1090.3940.2050.5940.160
N/L ratio0.0930.6270.1630.283-0.0800.6990.5600.058-0.4180.350

Discussion

CP is mainly a neuromotor disorder that affects the muscle tone, posture and development of movement.30 Precise CP diagnosis needs either an abnormality on an MRI scan and/or clinical history and motor dysfunction to ensure long-term functional outcomes based on positively modulating neuroplasticity.31

NTs are a family of proteins, which include BDNF, that are actively produced throughout the brain and are implicated in neuronal activity regulation; they also help and stimulate neurogenesis, which is why they are known to play an important role in both the recovery and protective function following neurodegenerative diseases.32

Many researchers have been dedicated to elucidating its role in pathological and physiological conditions. Multiple factors give complexity to the BDNF system, i.e., different receptors with their multiple signaling pathways, the functional isoforms and heterogeneous population of mRNAs, demanding more accurate procedures to make field improvements.33

In our study, the level of BDNF was significantly lower in the CP group compared with the control group. Hansen et al., stated that the reduced level of BDNF in the CP group was observed in children with severe CP, specifically low intake of n-3 fatty acids, energy, and dietary fibers and low physical activity levels.34 BDNF plays a great role in the development of the nervous system by affecting synaptogenesis, neurogenesis, neuronal development, growth and survival, synaptic plasticity and cell differentiation.19

AL-Ayadhi, suggested in her study a highly possible pathophysiological role played by BDNF in autism, as they also found significantly lower BDNF levels in participants with autism but it was not related to the severity level, this correlation may interpret the pathogenesis of autism and other possible neurological dysfunctions.35

Forsgren et al.,36 found a correlation between BDNF and TNF levels in patients with rheumatoid arthritis (RA), they stated that the level of BDNF was lowered significantly with anti-TNF treatment, which was associated with pain relief. Likewise, we found only a positive correlation between BDNF and TNF levels with spastic CP.

On the other hand, Siang Ng et al., suggested in their study that BDNF is increased in mild cognitive impairment (MCI) cases as a compensatory mechanism in preclinical dementia, supporting the partially inflammatory and neurotrophic hypotheses of cognitive impairment.22 Plasma BDNF appears to be a useful biomarker to differentiate MCI from patients with no cognitive impairment. This supports the suggestion that augmented peripheral BDNF acts as a compensatory mechanism in the preclinical stage of dementia.37

Palasz et al., suggested that NTs has been demonstrated that synaptic plasticity defects associated with insufficient neuronal supply of BDNF and other neurotrophic factors may contribute to neurodegenerative and neuropsychiatric diseases as in Parkinson’s and Alzheimer’s disease.38 Nevertheless, neither efforts to enhance BDNF expression with gene therapy nor direct delivery of exogenous BDNF into the patient’s brain led to any improvements.

Yeom et al., stated that a high peripheral BDNF concentration was found in preschool aged children with cognitive and attention intellectual disabilities, suggesting that it may help as a biomarker for any intellectual problems in early life.39

Weinstein et al., found that older adults with higher peripheral BDNF levels had lower chance of developing Alzheimer’s disease.21 Decreased BDNF levels may explain the lack of trophic support, contributing to neuronal degeneration.40

Furthermore, it has been shown that neurodegeneration and psychiatric diseases may be partially affected by low levels of BDNF and other members of the NT family.41 Therefore, a search is needed for new strategies to increase the levels of BDNF as a tool in the treatment and prevention of neurological diseases.38

Wu J et al., revealed that children with cerebral palsy have greater levels of TNF-α than controls42; this corresponded to our findings, in addition, they suggested that pharmaceutical therapies to reduce inflammation in infants with cerebral palsy may alleviate symptoms and warrant further investigation. Increased baseline TNF-α levels might be an indicator of more extensive brain damage when correlated with severity.

Also, it was suggested that the inflammatory response might diminish with age, whereas the cerebral palsy symptoms are not necessarily improved.43 Similarly, Soliman S et al., concluded that TNF-α levels in children with spastic CP are positively correlated with disease severity, showing a significant difference between pretreatment levels of TNF-α, which improved after rehabilitation and correlated with improvement in all outcome measures.44

Conclusions

BDNF has been shown to have a significant relationship with brain development early in life. However, further studies are needed to assess its value as a biomarker and/or as a treatment to enhance or avoid further complications of CP as still there is insufficient progress in prediction, early diagnosis, treatment, and prevention. Searching for novel strategies to increase BDNF levels may open a new opportunity for the treatment of neurological diseases.

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Hanna H, Youness ER, Orban HAA and El-Bassyouni HT. BDNF as a potential predictive biomarker for patients with pediatric cerebral palsy [version 1; peer review: 1 approved with reservations]. F1000Research 2022, 11:1347 (https://doi.org/10.12688/f1000research.127917.1)
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Reviewer Report 10 May 2024
Henrique Gouveia, Federal University of Pernambuco, Recife, Brazil 
Approved with Reservations
VIEWS 0
In general, I suggest having the text proofread by a native speaker, as there are some grammatical errors.
Abstract
- Given that the abstract needs to present the work in a complete way, I suggest adding some information. ... Continue reading
CITE
CITE
HOW TO CITE THIS REPORT
Gouveia H. Reviewer Report For: BDNF as a potential predictive biomarker for patients with pediatric cerebral palsy [version 1; peer review: 1 approved with reservations]. F1000Research 2022, 11:1347 (https://doi.org/10.5256/f1000research.140463.r269379)
NOTE: it is important to ensure the information in square brackets after the title is included in all citations of this article.

Comments on this article Comments (0)

Version 1
VERSION 1 PUBLISHED 18 Nov 2022
Comment
Alongside their report, reviewers assign a status to the article:
Approved - the paper is scientifically sound in its current form and only minor, if any, improvements are suggested
Approved with reservations - A number of small changes, sometimes more significant revisions are required to address specific details and improve the papers academic merit.
Not approved - fundamental flaws in the paper seriously undermine the findings and conclusions
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