Introduction

Malnutrition in children is expressly detrimental. The damage to physical and cognitive development during early childhood is largely irretrievable1. A wide range of cognitive deficits has been reported in malnourished children2. Malnutrition is linked to suboptimal brain development, which has a negative impact on cognitive development, educational achievement, and economic productivity later in life3. During childhood, the maturation of specific brain areas is associated with the development of specific cognitive functions, such as language, reading, and memory. Synaptic density reaches a high level of brain growth during childhood age, and brain myelination (which regulates higher cognitive functions) persists well into adolescence4.

The genetic program that determines how each person's brain develops is modified by the environment, including nutrition5. Studies have demonstrated a link between good nutrition and optimal brain function6,7. Healthy nutrition supplementation plays a critical role in cell proliferation, DNA replication, neurotransmitter, and hormone metabolism and is an essential component of enzyme systems throughout the brain8. Early in childhood, the brain grows more quickly than the rest of the body, which could make it more susceptible to nutritional deficits9.

One of the factors affecting cognitive development is nutrition. Early childhood may be especially vulnerable to nutritional deficiencies due to the rapid brain growth throughout this period. Children who are malnourished have higher mortality and morbidity rates10. In preschoolers, impaired cognitive development is predictive of later school achievement11. Education increases one's human capital or the knowledge, resources, and skills that eventually determine health and well-being12. Poor motor and cognitive development, lower educational attainment, economic output, and a higher chance of developing metabolic illnesses can all have an impact on productivity during adulthood, which is a public health concern13,14. Studies have reported poor motor skills, adaptive behavior, language, and social skill development among malnourished children. Malnutrition is also linked to deficits in memory, visuomotor coordination, and social skills. Also, decreased IQ scores were associated with the severity of malnutrition2.

Despite the efforts of national and international obligations, the knowledge gaps of caregivers remain a cause for the nutritional status of children, and it affects physical growth and cognitive development. Considering this, the current study made an effort to give mothers comprehensive nutrition education to increase their understanding of and sensitise them to the prevention and management of malnutrition, change dietary habits, and enhance their children's cognitive development.

Material and methods

Study design and sample

This study employed a cluster-randomised controlled trial design. The cluster of moderate and severe uncomplicated underweight preschool children between three and five years of age attending Anganwadi centers and their mothers in rural areas of Udupi district, Karnataka, were included in the study. Udupi district is a coastal part of Karnataka, India (Fig. 1).

Figure 1
figure 1

Area map of study location.

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Sample size

The sample size for the study was calculated considering 80% power, 5% level of significance, an attrition rate of 20%, a design effect of 1.5, an improvement of cognitive status in the standard of care of 30%, and 50% improvement in researcher intervention. Considering these, the required sample size was 230 for the intervention and control groups (115 in each group). Thus, 253 samples were included in the study from the selected clusters (127 + 126).

Eligibility criteria for selection of sample

Inclusion criteria

The study included children between 3 and 5 years with moderate and severe underweight registered in Anganwadi centers and their mothers who could read/write/understand Kannada (local language) or English.

Exclusion criteria

Children aged between 3 and 5 years with known cases of systemic illness such as cardiac problems, renal problems etc., and not registered in Anganwadi centers were excluded from the study.

Ethical approval

All methods were carried out in accordance with relevant guidelines and regulations. The study was approved by Kasturba Hospital Manipal, Institutional Ethics Committee and registered in the Clinical Trial Registry of India (CTRI/31/03/2017/008273). Reference number (REF/2016/08/012051) link http://ctri.nic.in/Clinicaltrials/pmaindet2.php?trialid=15547&EncHid=&userName=.

A detailed subject information sheet was given in the local language (Kannada) to all the mothers, and informed consent was obtained from each mother after explaining the purpose of the study and methodology and ensuring the confidentiality of the data obtained.

Assessment of cognitive status

The cognitive status of the children was assessed with a standardized tool, “Cognitive development test for pre-scholars Scale” (PCDTP-p)15 for Indian children between 3 and 6 years of age by verbal and non-verbal tests. Dr Hema Pandey developed the tool to assess the cognitive development of Indian preschoolers. The tool includes six areas such as conceptual skills, information, comprehension, visual perception, memory, and object vocabulary. The tool had high validity, and the author reported test re-test reliability value is r = 0.95. The researcher also checked the current setting's content validity (CVI = 1) and reliability using the test re-test method (r = 1).

The assessor administered the test individually in an exclusively private room. Each child was given sufficient time to complete all the test items. Before the test, the child was made physically comfortable. Test results were recorded simultaneously on the scorecards. For each correct answer, one mark was awarded. The total score constituted the ‘raw’ scores of the subject (child). The total raw scores were converted to standard scores as per their age according to the table of norms and instructions provided along with the tool by the original authors of the tool. The following formula for conversion of raw score to standard score (Z-scores) was used. Z-Score = (X−M/SD): where X, score; M, mean of the raw score; SD, standard deviation of raw scores.

Based on the z score, the child’s cognitive development was interpreted (Table 1).

Table 1 Interpretation of the status of cognitive development.
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Randomization and procedure for data collection

Cluster randomization was adopted to select the villages. Twelve villages were chosen randomly for the study. Clusters of six villages were randomly assigned for the intervention, and six villages to the control group using the lottery method by the researcher. All Anganwadi centers belonging to allocated villages were included. Based on anthropometric indices, malnutrition status was identified. All malnourished children who met the inclusion criteria were included in the study. One hundred twenty-seven preschool children and their mothers from 27 Anganwadi centers in six villages were recruited for the intervention group, and 126 preschool children and their mothers from 30 Anganwadi centers in six villages were recruited for the control group (Fig. 2). Data were collected between March 2018 and May 2019. The researcher visited Anganwadi centers, and the weight and height of the children were measured. We evaluated the children’s nutritional status using weight-for-age and height-for-age indicators and graded the malnutrition level per NCHS’s new WHO child growth standards16. Moderate underweight was defined as a weight-for-age ratio of less than − 2 z score, severe underweight was defined as weight for age less than − 3 z score, and stunting was defined as a height-for-age − 2 z score. Moderately and severely underweight preschool children and their parents were selected for the study. The mothers of the malnourished children were met and informed about their children’s malnutrition, the purpose of the study, the data collection procedure, intervention, and follow-ups. The date and time for intervention at the Anganwadi center were set. The study’s nature was explained in detail, a subject information sheet was distributed in the local language, and informed consent was obtained.

Figure 2
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CONSORT (2010) flow diagram of the study.

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After the mother signed the informed consent, baseline information was collected from the mother, and the researcher assessed the children’s cognitive development. With the help of power points, posters, and flipcharts, the mothers were educated on malnutrition, its causes, signs, and symptoms, how to identify malnutrition, the consequences of malnutrition on health and development in a child’s life, and a discussion was held on methods to prevent and manage malnutrition at home. A balanced diet, a malnourished child’s dietary requirements, and a sample diet menu plan for moderate and severe malnourished preschool children were also discussed.

One of the nutritious recipes, i.e., mixed vegetables and gram (paustic khichdi), was demonstrated. Additionally, the preparation of various healthy recipes rich in protein, energy, calcium, and iron were explained. The module on the Home-based management of malnutrition was given to the mothers, and they were advised to read it well and follow the practices presented in the module. Mothers were asked to prepare anyone nutritious food daily (or at least four times per week) and maintain a diary. They were also asked to send pictures of feeding the child with the recipe and clarify their doubts during the follow-up visit or telephonically. The monthly nutritional level assessment was carried out, and the findings are published20.

Follow-up and outcome measurement

Mothers’ queries were answered during the intervention phase, and suggestions were given when children had problems. Diary on nutritious diet preparation maintained by the mothers and dietary practices were checked during follow-up.

The outcome assessor performed an outcome assessment of cognitive development. The outcome assessor is a trained, qualified, graduated registered nurse and was blinded by the study group. The outcome measurement of cognitive development assessment was assessed at the end of six months (midline test) and 12 months (endline test) after the intervention in both groups.

Data management and analysis

Data from 253 participants (Fig. 2) were pooled and analyzed using SPSS version 16. A chi-square test was carried out to test the homogeneity of baseline outcome variables among the intervention and control groups. The McNemar test and chi-square test were used to compare the cognitive improvement within and between the groups.

Baseline characteristics of enrolled children

The mean age of children in the intervention group was 4.08 ± 0.71, and in the control group, it was 3.95 ± 0.68. A maximum number of children in both groups belonged to the family with a family income of less than 10,000 rupees/per month. The educational status of the parents (both mother and father) was lower in the intervention group than in the control group. Most of the fathers' occupations were reported as self-employed and mothers’ occupation were reported as small/self-business in both groups (Table 2). However, the comparison of baseline characteristics of both groups showed that, except for parents’ educational level, both groups were similar at baseline (Table 2).

Table 2 Baseline characteristics of enrolled children.
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Effect of intervention on cognitive development of malnourished preschool children

Table 3 demonstrates that most of the malnourished children in both groups at baseline had average and above-average cognitive development (intervention and control group). At baseline, 52% of children in the intervention group were classified as having average cognitive development; however, these numbers dropped by 14.2% in the midline test and 5.5% in the endline test and moved to the category of high and extremely high development. At the start of the trial, 44.4% of the children in the control group had average cognitive development; this number dropped to 28.6% at the midline and 26.2% at the endline test. Similarly, compared to the control group, more children in the intervention group scored high in the high and extremely high development categories on the midline and end-line tests (Table 3).

Table 3 Frequency and percentage distribution of preschool children in the intervention and control groups based on levels of cognitive development status at different points of assessment.
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Comparison of cognitive development status within the intervention group

Table 4 shows a significant difference in the baseline and midline test (Mc \(\upchi\)2(df) = 78.89(1), p =  < 0.001); baseline and endline test (Mc \(\upchi\)2(df) = 53.94(1), p =  < 0.001) of cognitive development scores. It is inferred that there was a significant improvement in the cognitive development scores of children in the intervention group over 12 months.

Table 4 Effect of intervention on cognitive development status in the intervention group.
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Comparison of pretest and post-test cognitive development status between the intervention and control groups

There was a significant improvement in children’s cognitive development from the baseline to the midline test. At six months of intervention (midline), 82 (64.6%) and 72 (57.1%) in both the intervention and the control group, respectively, were in the positive change category of cognitive development. The more positive category was higher (21.3%) in the intervention group than in the control group (12.7%), which was statistically significant (p = 0.006) (Table 5).

Table 5 Comparison of pretest and midline test cognitive development status between the intervention and control groups.
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In the intervention group, there was a significant increase in cognitive development from the pretest to the endline test, which was statistically significant (p < 0.001). In the midline and end-line tests, children in the intervention group moved from positive change (21.3%) to more positive change (36%). However, it was noticed that the more positive difference in the control group declined from the midline test (16, 12.7%) to the endline test (7, 5.6%). This explains a substantial difference in preschoolers' cognitive development between the intervention and control groups (Table 6).

Table 6 Comparison of pretest and endline test cognitive development status between the intervention and control groups.
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Discussion

Various factors, including nutrition, influence the brain development. Nutritional deficiencies may have a significant impact on brain development9. In this study, we found that most of the preschoolers with malnutrition had poor cognitive development. We observed that 52% of malnourished preschool children in the intervention group and 44.4% in the control group had average cognitive development. We observed that, except for the motor speed and coordination test, malnourished children performed poorly on tasks requiring attention, working memory, learning and memory, and visuospatial ability. A study found that cognitive skills such as working memory, visual construction, learning, and memory in malnourished children were not developed as per age compared to adequately nourished children2, which supports the current study's findings.

In another study, children with malnutrition obtained lower social quotient scores than normal children. The effect was more noticeable in stunted, wasted children with poor communication and socialisation skills. Additionally, malnutrition had a significant relationship with immediate and delayed memory17. Higher absenteeism, falling sick, and poor school performance were found among Filipino children18.

Significant improvement in the cognitive development of preschool children was observed after implementing community-based nutrition intervention. The intervention developed and delivered was context-specific and affordable to the rural population19. Mothers exhibited enthusiasm in preparing varieties of nutritious food that were readily available and affordable to the family. We also observed an improvement in nutritional status among these children20. A community-based study from Indonesia reported improvement in the growth and development of children19. A systematic review of the effectiveness of early childhood interventions in promoting cognitive development revealed that the implementation of comprehensive programs on cognitive development was very effective. Interventions such as child-focused education and stimulation, parent-focused support, income supplementation, and nutrition and health interventions were effective in improving the cognitive development of children21. Food prepared by the mothers promote weight gain and cognitive development because the mothers can find food sources based on local availability, and children prefer local food prepared by the mothers22. Nutrition education intervention can improve the child’s growth parameters and overall development, including cognitive development. This intervention can be implemented within the integrated child development scheme (ICDS) framework so that mothers can provide nutritious diets to their children within their socioeconomic capabilities.

Strength of the study

The outcome assessor, blinded to the study group, performed an outcome assessment of cognitive development. The outcome measurement, cognitive development, was assessed for a long duration, i.e., at the end of six months and 12 months after the intervention in both groups.

Limitations of the study

The study included only preschool children and their mothers registered in the Anganwadi centres of selected villages of Udupi taluk. The intervention and control groups differed in terms of the parent’s educational level. The researcher could not control this as the study adopted cluster randomization.

Conclusion

Malnutrition among children impacts their cognitive development. Thus, caregivers must be made aware of the effect of malnutrition on cognitive development so that they will be able to identify these deficits early and take corrective measures. Parenting and its related feeding practices in the first five years of life are closely related to stimulating children's overall growth and development.