Malnutrition is the consequence of a combination of inadequate intake of protein, carbohydrates, micronutrients and frequent infections [1
]. In India malnutrition is rampant. WHO report states that for the years 1990–1997 52% of Indian children less than 5 years of age suffer from severe to moderate under nutrition [2
]. About 35% of preschool children in sub-Saharan Africa are reported to be stunted [3
]. Malnutrition is associated with both structural and functional pathology of the brain. Structurally malnutrition results in tissue damage, growth retardation, disorderly differentiation, reduction in synapses and synaptic neurotransmitters, delayed myelination and reduced overall development of dendritic arborization of the developing brain. There are deviations in the temporal sequences of brain maturation, which in turn disturb the formation of neuronal circuits [1
]. Long term alterations in brain function have been reported which could be related to long lasting cognitive impairments associated with malnutrition [4
A wide range of cognitive deficits has been observed in malnourished children in India. In a study, malnourished children were assessed on the Gessell's developmental schedule from 4 to 52 weeks of age. Children with grades II and III malnutrition had poor development in all areas of behaviour i.e., motor, adaptive, language and personal social [5
]. Rural children studying in primary school between the ages of 6–8 years were assessed on measures of social maturity (Vineland social maturity scale), visuo-motor co-ordination (Bender gestalt test), and memory (free recall of words, pictures and objects). Malnutrition was associated with deficits of social competence, visuo-motor coordination and memory. Malnutrition had a greater effect on the immediate memory of boys as compared with those of girls. Malnourished boys had greater impairment of immediate memory for words, pictures and objects, while malnourished girls had greater impairment of immediate memory for only pictures. Delayed recall of words and pictures of malnourished boys was impaired. Malnourished girls had an impairment of delayed recall of only words. The same authors measured the intelligence of malnourished children using Malin's Indian adaptation of the Wechsler's intelligence scale for children. IQ scores decreased with the severity of malnutrition. Significant decreases were observed in performance IQ, as well as on the subtests of information and digit span among the verbal subtests [6
]. The above study has shown that though there is decrease in full scale IQ, yet performance on all the subtests was not affected. This suggests that malnutrition may affect different neuropsychological functions to different degrees. Studies done in Africa and South America have focused on the effect of stunted growth on cognitive abilities using verbal intelligence tests based on assessment of reasoning [7
]. Such an assessment does not provide a comprehensive and specific assessment of cognitive processes like attention, memory, executive functions, visuo-spatial functions, comprehension as conducted in the present study. Information about the functional status of specific cognitive processes has implications for developing a cognitive rehabilitation program for malnourished children.
A neuropsychological assessment would throw light on functional status of brain behaviour relationships affected by malnutrition. Deficits of cognitive, emotional and behavioural functioning are linked to structural abnormalities of different regions of the brain. Brain structures and brain circuits compute different components of cognitive processes [8
]. Malnutrition has long lasting effects in the realm of cognition and behaviour, although the cognitive processes like executive functions have not been fully assessed [9
The differential nature of cognitive deficits associated with malnutrition suggests that different areas of the brain are compromised to different degrees. A neuropsychological assessment would be able to delineate the pattern of brain dysfunction. Malnutrition is a grave problem in our country as 52% of our children are malnourished. Effects of protein-calorie malnutrition are inextricably blended with the effects of social cultural disadvantage; even within the disadvantaged class, literacy environment at home and parental expectation regarding children's education are powerful variables. Perhaps membership in a higher caste confers some advantage in regard to home literacy, and parental expectation. Short and tall children do differ in some cognitive tests, but not in all as demonstrated in a study done in Orissa, India [10
]. But whether or not stunted growth alone is the causative variable for cognitive weakness is not determined as yet. Moreover, the functional integrity of specific cognitive processes is less clear. Chronic PEM resulting in stunting and wasting could result in delay in the development of cognitive processes or in permanent cognitive impairments. Neuropsychological measures can demonstrate delay in normally developing cognitive processes as well as permanent cognitive deficits.
The present study is an attempt to investigate the effect of stunting (as a result of PEM) on the nature of cognitive impairments and on the rate of cognitive development. Neuropsychological measures, standardized with respect to the age trends of cognitive processes in children in the age range of 5–15 years have been employed which would also inform about the neuropsychological performance of malnourished children. The study aimed to investigate if malnutrition would result in a diffuse impairment and a general slowing in the rate of development of all cognitive processes or these effects could be present for some specific cognitive processes. The purpose was also to determine the cognitive processes that are more vulnerable to the effects of malnutrition in two ways: in terms of impairment without affecting the rate of development and with respect to the effect on the rate of development of cognitive processes itself.