Socio demography of mental retardation: A community-based study from a goitre zone in rural sub-Himalayan India

Introduction

Mental retardation is defined by the American Association on Mental Retardation (AAMR) as “significantly sub-average intellectual functioning existing concurrently with related limitations in two or more of the following applicable adaptive skill areas: Communication, self-care, home living, social skills, community use, self-direction, health and safety, functional academics, leisure and work, with such limitations manifested “before the age of 18.”[1]

Mental Retardation is one of the most common disabilities occurring in childhood.[2] Studies of the frequency of and risk factors for cognitive disorders in children have almost entirely been limited to the developed countries where service records and registries provide feasible means of case identification.[3] Pilot studies of severe mental retardation in selected populations conducted in India and Pakistan have reported extraordinarily high prevalence estimates in the range of 12–24/1000.[4] Because some of the specific causes and risk factors that are now uncommon in developed countries remain highly prevalent in less developed countries, and because child survival is beginning to improve in some countries (a situation which in developed countries appears to have resulted in increase in the prevalence of childhood disabilities), the possibility of an elevated frequency of severe mental retardation in less developed countries is plausible and requires confirmation.

District Kangra forms a part of the 2400 km long goitre belt along the southern slopes of the Himalayas. Various studies have been carried out in this district on iodine deficiency and prevalence of goitre, but even after an extensive search on PubMed, no work on the prevalence and causes of mental retardation carried out in this district were found. Iodine deficiency forms one of the major causes of mental retardation among children. Prevalence estimates of mental retardation are important for determining the educational and health care needs of the children with this condition. Population-based epidemiological studies on childhood disabilities are needed for identifying risk factors and causes, and for needs assessment to facilitate planning of services for children and families with special needs. Studies across populations need to be undertaken as a consideration of culture is essential in the process of the interview, case formulation, diagnosis, and treatment of culturally diverse individuals. Furthermore, the evaluation of these individuals raises many issues that clinicians need to address to formulate an accurate diagnosis and treatment plan that will be acceptable to the patient.

Materials and Methods

Kangra district of Himachal Pradesh lies between 31°21’ to 32°59’ N latitude and 75°47’ to 77°45’ E longitude. It is situated on the southern escarpment of the Himalayas. The total geographic area of Kangra district is 5,739 sqkm.

A cross-sectional two-phase study was carried out in a single block in the rural area of district Kangra, with a population of about one lakh block. A total of five panchayats with a population of about 12,000 were randomly selected. During the first phase of the study, a door to door survey was conducted. The consent for the participation in the study was obtained from the guardian (preferably parents) of the children. All the children within the age group of 1–10 years were screened using the ten questions screen.[5] The ten questions screen has been used by the researchers across populations for the assessment of mental retardation.[345]

The sensitivity of ten questions as a global screen for serious cognitive, motor and seizure disabilities is high (84–100%). Five of the questions focus specifically on cognitive development, two questions relate to movement disability, and one question each focuses on seizures, vision and hearing respectively.[5] Importantly the children of this age group represent iodine nutriture of a community.[6]

Results

The crude prevalence of mental retardation in this region was found to be 2.15%, which is higher than prevalence reported in other parts of the country. According to the modified Uday Parekh scale used for assessing the socio-economic status of the families of the children examined in the first phase, 686 (28.3%) belonged to middle class, 1670 (69%) belonged to the lower middle class and 64 (2.6%) belonged to the lower class [Table 1].

Table 1 Socio-economic status (using Uday Parekh scale) of the study population

Maximum children with mental retardation belonged to the lower middle class, wherein of the 1670 children examined, 41 were found to be mentally retarded (2.4%). A total of 8 children of the 686 belonging to the middle class were found to be mentally retarded (1.16%) and 3 children of the 63, belonging to the lower class, were found to be mentally retarded (4.7%) [Table 2].

Table 2 Socio-economic status (using Uday Parekh scale) of the mentally retarded

The prevalence was more among males as compared to the female children. About 59.6% (31/52) of the mentally retarded children were males. Of these 16.1% (5/31) male children belonged to the middle class, 77% (24/31) belonged to the lower middle class and 6.45% (3/31) belonged to the lower class. About 40.3% (21/52) of mentally retarded children were females. Of these 14.2% (3/21) belonged to the middle class, 80.95% (17/21) lower middle class and 4.7% (1/21) belonged to the lower class.

The variable which is of interest, as it was found to be statistically significant from among the Uday Parekh scale was the education status of the father (P = 0.001) [Table 3]. About 46.1% children were from families where the father had attended high school and 28.8% of the mentally retarded belonged to fathers who had attended middle school.

Table 3 Education status of fathers of mentally retarded children (N=52)

Discussion

The prevalence of mental retardation has greatly varied across the different countries of the world with Atlanta, Georgia, US 0.33%,[7] UK 0.34%,[8] Australia showing a prevalence of 0.3%,[9] Canada with a prevalence of 0.72%[10] and China showing a prevalence of 0.93%.[11] In a study conducted in eight developing countries, a variation in prevalence of mental retardation was found from 0.9% (Philippines) to 15.6% in Bangladesh.[12]

The prevalence of mental retardation in India has shown a variation from 0.72% in J and K,[3] 0.3% in Mangalore[13] to 2.3% in Karnataka.[14] Our study revealed a prevalence of 2.15%, which is on the higher side as compared to the rest of the country. The survival rate of children in Himachal Pradesh is quite high due to the efficient primary health care system in the state. The percentage of institutional deliveries in Himachal Pradesh is high (70% in 2011–12). This probably leads to the survival of children who have congenital anomalies or suffer birth trauma and later present with mental retardation. The study reveals that most of the children belonged to the lower middle class and lower class families. The living conditions of the family, the occupation and the education of the father could be an important factor in the development or the diagnosis of mental retardation. Most of the fathers had attended high school. This could possibly be because educated parents are able to identify mental disorders and delay in developmental milestones better than lesser educated parents and hence are able to give better history. The fear of social stigma may also be lesser among the educated people than the uneducated ones.

The low-socio-economic status is the strongest and the most consistent predictor of mild mental retardation. Islam et al. in their study in Bangladesh found the prevalence of severe mental retardation to be 0.5% and mild-mental retardation 0.14%. Prevalence of mild-mental retardation was found to be strongly and significantly associated with low-socio-economic status.[15] Strome et al. in a cross-sectional study in Oslo, Norway found a high risk of mild mental retardation in families with a low-socioeconomic status. However, they also state that parents of children with severe mental retardation belonged to the higher socio-economic strata.[16] A study in Australia showed that children of mothers in the most disadvantaged 10% had five times more the risk of mild and moderate ID as compared with those in the least disadvantaged 10%.[17]

This highlights the role of poverty and social deprivation in the development of mental retardation. Perinatal infections, post-natal infections and lack of screening for congenital/chromosomal disorders are some of the common causes of mental retardation which are more often seen in the lower income strata of society. Further, the prevalence of certain other childhood conditions like cerebral palsy or other motor deficits, language delays, or hearing needs to worked out for arriving at true prevalence of mental retardation. Such motor or sensory impairments can mimic cognitive impairment, but are not in themselves causes of it. As children mature, some develop anxiety or depression if they are socially rejected by other children or if they are disturbed by the realization that others see them as different and deficient. Well-managed, inclusive school programs can help to maximize social integration, thereby minimizing such emotional responses. Appropriate medical care and education given to the lower middle class families could go a long way in reducing mental retardation among children.