Introduction:

Studies on developmental psychopathology have shown that several problems and disorders that started during childhood persist into adulthood. Recent epidemiological studies have emphasized the need for the early identification of problems and disorders in childhood and adolescence that may eventually lead to other psychopathologies in adulthood.

A previous paper presented the rationale and development of a brief instrument which could be used to early identify clinical risk conditions in children by health professionals: the Brief Screening and Diagnostic Questionnaire, CBTD. The CBTD is a 27-item questionnaire which is answered by the parents of the child exploring symptoms frequently reported as motives for seeking attention at the out-patient mental health services. The instrument showed good reliability, KR-20= 0.81, and construct validity for identifying groups of symptoms that suggest the presence of the most frequent psychiatric syndromes in children and adolescents.

As our goal was to identify probable psychiatric disorders, and diagnostic criteria are not equal to clusters of symptoms identified by factor analyses, the next task was to explore the data using a different statistical technique and to develop observational units, syndromes, for further clinical evaluation. The objectives of this paper are: 1. to present the resulting algorithms and 2. their prevalence in children and adolescent population in Mexico City.

Method:

The CBTD was included as part of the instruments used in an epidemiological study on psychiatric morbidity in Mexico City. The study was designed as a household survey on a representative sample of the adult population aged 18-65 years in Mexico City. In addition, information was obtained about all the respondents’ children aged 4-16 years living at the same household. The total sample included 1685 children and adolescents with the following distribution by age-groups: 16.3% were 4-5 years old; 25.5%, 6-8 years old; 30.9%, 9-12 years old, and 27.4%, 13-16 years old.

Once the independence of the observations was assured, logistic regression analyses were performed between cardinal symptoms for different diagnoses and the rest of the items from the questionnaire. Statistically significant associations were evaluated clinically and compared to psychiatric syndromes as defined by the DSM-IV and ICD-10 classifications. Based on these results, algorithms for probable psychiatric syndromes were created.

Results:

Using the results from logistic regression analyses, algorithms were created considering different levels of severity for probable disorders: attention-deficit and hyperactivity distinguishing three subtypes, depressive with two definitions and two severity degrees, anxiety with two subtypes, oppositional behavior, conduct disorder, specific language disorder, epilepsy, and other clinical conditions such as problems related with eating attitudes, enuresis and impulsivity.

Depressive and hyperactive attention-deficit syndromes were the most frequent in the population. Among these groups of syndromes, depression, as defined in terms of the presence of irritability or sadness and three or more associated symptoms, and the combined subtype of hyperactive attention-deficit, were the most prevalent. Oppositional behavior and anxiety syndromes were also frequent, and all of the afore mentioned syndromes appeared predominantly associated at least with another one. Mixed externalizing and internalizing syndromes were found in 5% of the population, while only internalizing syndromes were reported in 4.5% and only externalizing syndromes in 2.4%.

Although as a whole no significant differences by sex were found on the number of syndromes presented, in males the frequency increased with age, while in girls more syndromes were reported on the youngest and elder age-groups.

Discussion:

This paper has presented operational definitions for screening syndromes based on the associations among symptoms explored by the CBTD in children and adolescents of the general population in Mexico City.

It is important to highlight that the CBTD is based on symptoms which are frequently reported as motives for consultation. So, the instrument does not merely translate diagnostic criteria into questions but rather use the way in which the population perceive and express concern about their children’s behavior, in order, first, to define caseness and, second, to identify probable disorders.

Recently, Goodman designed an interesting brief instrument, the Strengths and Difficulties Questionnaire (SDQ), that generates scores for conduct problems, inattention-hyperactivity, emotional symptoms, peer problems, and prosocial behavior. One difference between the CBTD and the SDQ is that the former in- cludes items exploring language problems, enuresis, and seizures, which are clinically relevant and frequently associated with conduct and emotional problems. Furthermore, 4% of our study population presented these kind of problems associated with externalizing or internalizing syndromes.

Results indicating that attention-deficit and depressive syndromes are the most common in the population are consistent with the most frequent disorders attended at the Pediatric Psychiatric Hospital in Mexico City. Also interesting is the fact that in a National Psychiatric Epidemiological Survey, 2% of the adult population with depressive disorders reported having their first depressive episode during childhood or adolescence with a mean duration of 31 months. Likewise, results from the present study found that 2.6% of the children and adolescents have the most severe depressive syndrome, IDEP-2S, which also has the highest diagnostic specificity in clinical settings.

These results suggest that the CBTD accomplishes the goal of being a useful tool for epidemiological studies and for the surveillance of mental health in childhood and adolescence. The presence of a syndrome does not lead automatically to a psychiatric diagnosis. The intention is that, in those cases, corroboration should be sought by evaluating interference caused by the reported symptoms in familial, school, social and personal functioning.

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