Using the World Health Organization Composite International Diagnostic Interview (CIDI), the US National Comorbidity Survey–Adolescent Supplement (NCS-A) surveyed 10,123 adolescents aged 13 to 18 years. This study was launched as an initiative to address the lack of national statistics on mental health in children. The methodology was of a dual frame with a household subsample and a school subsample. The CIDI was modified for use with adolescents, and information from both the parent and adolescent was combined for major depression and behaviour problems. DSM-IV criteria were used (Merikangas et al. 2010).

The overall lifetime prevalence of disorders with severe impairment or distress was 22 %. The details are given in Table 1.2. Anxiety disorders were the most commonly reported with 8 % having severe impairment. It is important to note the early age of onset of anxiety disorders, followed by behaviour, mood and substance abuse disorders. The early age of onset of disorders highlights the need for early intervention (Table 1.2) (Merikangas et al. 2010).

In this important study undertaken in Bangalore, a sample size of 1,578 children was selected including 438 urban children, 481 slum children and 659 rural children. The prevalence rate in the 4–16-year-old children was 12.0 %. Enuresis, specific phobias, hyperkinetic disorders, stuttering and oppositional defiant disorder were the most frequent diagnoses. When impairment associated with the disorder was assessed, significant disability was found in 5.3 % of the 4–16-year-olds. Middle-class urban families were more likely to report psychiatric morbidity but also recorded the maximum drop in rates, when impairment criteria were included. The urban slum areas had the lowest total prevalence rates possibly due to greater toleration of deviance and low awareness of problems (Table 1.3).

In the Goa study, 2,048 adolescents aged 12–16 years were evaluated for psychiatric disorders. The most common diagnoses were anxiety disorders (1.0 %), depressive disorder (0.5 %), behavioural disorder (0.4 %) and attention-deficit hyperactivity disorder (0.2 %). Where both sets of informants were interviewed, a higher rate of diagnosis was made. Of the 20 individuals diagnosed with anxiety disorders, 10 individuals had a depressive disorder, 9 individuals had behavioural disorders and 4 had ADHD. In this study, the authors stated that the prevalence could be low for three possible reasons: methodological factors, the scope of the study and the prevalence of protective factors (Table 1.4).

In a cross-sectional study, the Childhood Psychopathology Measurement Schedule (CPMS) was used to screen 982 students in the age group of 10–15 years from four randomly selected schools. The screening was followed by detailed evaluation in which children were diagnosed by ICD-10 criteria. One hundred and ninety-nine (20.2 %) students had psychiatric morbidity. Specific phobias were the largest group amounting to nearly 20 % followed by sleep disorders. Tension headache was reported in 11.5 %. Hyperkinetic disorder was found in 6 %, conduct disorder in 1 %, and depressive episodes in 2 % of children (Bansal and Barman 2011).

In a sample of 1,014 school- and college-based adolescents aged 13–19 years, the Beck’s depression Inventory was used to find the prevalence and pattern of depression. School dropouts had the most severe and extreme forms of depression. There was 3 % depression in school-going adolescents and none in college-going adolescents. Prevalence of severe and extreme depression among adolescents using BDI was 9.5 and 1.7 %, respectively, among school dropout girls, 2.6 and 0.2 %, respectively, among school-going girls, 1.4 and 0.2 %, respectively, among school-going boys and nil among college-going girls (Nair et al. 2004) (Table 1.5).

The BDI has been found to be a sound measure for use in a primary care setting in India (Basker et al. 2007).

In a rural sample of 500 rural adolescents, the prevalence for all anxiety disorders was 8.6 % when the international cut-off of 31 was used for SCARED and 25.8 % when the Indian cut-off of 21 was used and 14.4 % when DSM-IV-TR criteria were used. The respective figures for boys and girls were boys = 2 %; girls = 6.6 % (cut-off 31); boys = 6.6 %; girls = 19.2 % (cut-off 21) and boys = 4.8 %; girls = 9.6 % (DSM IVTR) (Table 1.6).

In the NCS-A study, of the affected adolescents, 61 % met criteria for a single disorder. Twenty-five per cent of adolescents affected by one disorder also met criteria for a second disorder, 11.0 % were affected by three classes of disorders, and 3 % were affected by four classes of disorder (Merikangas et al. 2010).

In the Trivandrum sample, depressive disorders were concurrently present in 23.7 % of adolescents with AD. Conversely, 20 % of adolescents with panic disorder, 12.1 % with generalized anxiety disorder, 5.3 % with separation anxiety disorder and 12 % with social anxiety disorder also had depressive disorders (Nair et al. 2004).

In the only Indian incidence study on childhood psychopathology, in a 6-year follow-up study in Chandigarh, children who scored below the cut-off for psychiatric disorder (N = 727) on both the screening instruments used were recontacted 6 years later. Assessments were done by qualified psychiatrists and by well-structured and standardized scales, using ICD 10 criteria. Assessment scales included lifetime versions of symptoms. The follow-up strategy was intensive door-to-door survey. One hundred and eighty-six children and their families were available for re-evaluation. Twenty children out of 186 followed up were identified to have psychiatric disorder. This gives the incidence rate of 18/1000/year. Ten (50 %) children fell into the category of neurotic, stress-related and affective disorders, and 2 (10 %) children had personality and behaviour disorders. These conditions are basically adult disorders which had onset during childhood. Only 8 (40 %) children presented with disorders that have onset specific to childhood (Table 1.5). The methodology excluded children with severe psychopathology as it was a school-based study. Brief disorders of adjustment might have been missed as the group was assessed after a period of six years.

In the NCS-A study, the prevalence of ADHD was 8.7 %, with three times as many males being affected by this condition as females. The prevalence of severe ADHD was 4.2 %, or approximately half of all cases in the sample. Srinath et al. reported a point prevalence estimate for hyperkinetic disorder to be 1.6 %. Pillai et al. reported a rate of only 0.2 % in adolescents aged 12–16 years. In a recent study, in 770 children aged between 6 and 11, the prevalence of ADHD was found to be 11.32 % (Venkata and Panicker 2013).

ODD was present in 12.6 % of the sample (6.5 % for severe cases) and 6.8 % met criteria for CD (2.2 % for severe cases). Although the rates of ADHD and ODD remained relatively stable by age group, rates of CD increased to a peak of 9.6 % among the oldest adolescents (Merikangas et al. 2010). The median 12-month prevalence rate of disruptive behaviour disorders (i.e., conduct disorder or oppositional defiant disorder) is 6 % (range 5–14 %) in studies conducted in developed countries. Srinath reported the prevalence for conduct and oppositional defiant disorder to be 1.3 % whilst Pillai, reported a rate of 0.4 % for disruptive behaviour disorders (Srinath et al. 2005; Pillai et al. 2008).

In a random sample of 240 school students, conduct disorder was found in 4.58 %, the ratio of boys to girls being 4.5:1. Childhood onset was found in 73 % and adolescent onset in 27 % (Sarkhel et al. 2006).

In community samples, estimating prevalence rates of somatic symptoms, somatoform disorders and pain disorders including headache can be fraught with dangers. Epidemiological studies cannot rule out the prevalence of organic disorders. Early studies of abdominal pain from developing countries have cited high rates of infestations and other organic underlying conditions (Balani et al. 2000). Clinic-based figures tend to give a better idea of the number of referrals that fit the diagnosis which has features of prominent somatic symptoms associated with distress or impairment (Fiertag et al. 2012).

In a Norwegian cross-sectional study of 230 boys and 189 girls in grades 1–10, perceived loneliness showed strong and positive associations with sadness, anxiety and headache, with consistently stronger associations for girls than boys. Necessary help from teachers was associated with lower prevalence of stomach ache in girls (Løhre et al. 2010).

In an older German study, with lifetime prevalence of DSM-IV somatoform symptoms, syndromes and disorders in a representative sample of 3,021 adolescents and young adults aged 14–24, an overall prevalence rate of 12.6 % was found. Somatoform disorders were relatively rare with a lifetime rate of 2.7 %, but a considerably higher proportion of respondents met criteria for other disorders like undifferentiated somatoform/dissociative syndrome USDS lifetime prevalence 9.1 % (Lieb 2000).

In a report of hospital-based prevalence, children and adolescents attending the behavioural Paediatrics Unit made up 2.71 % of the annual attendance. Somatoform disorders accounted for 12.12 % of psychiatric referral (Jayaprakash 2012).

In another clinic-based survey, the prevalence of somatoform disorders was 0.59 % (103 among 17,500) and 0.78 % (21 among 2,678) among outdoor and indoor paediatric patients, respectively. The mean age of the study group was 13.2 ± 2.8 years. Among the 124 children (40 boys and 84 girls) meeting ICD criteria, conversion disorder was the commonest (57.3 %), followed by undifferentiated somatoform disorder (25.2 %). Fainting attacks and ataxia were common in conversion disorder. Pain in abdomen and headache were more frequent in other somatoform disorders. Stressors were identified in 73.4 %, and acute precipitating stressors were present in 14.4 % children (Bisht et al. 2008). In another school-based study, tension headache was reported in 11.5 % of adolescents (Bansal and Barman 2011).