studies comparing Swedish-Finnish bilingual children and Swedish monolingual children between the ages of five to seven have also shown that the bilingual children have a smaller vocabulary than monolingual children. In another study throughout America, elementary school English-monolingual children performed better in mathematics and reading activities than their non-English-dominant bilingual and non-English monolingual peers from kindergarten to grade five. Learning two languages simultaneously can be beneficial or a hindrance to a child's language and intellectual development. Further research is necessary to continue to shed light on this debate. In addition to the study of bilingualism in children, similar research is being conducted in adults. Research findings show that although bilingual benefits are muted in middle adulthood, they are more profound in older age when those who develop dementia experience onset about 4.5 years later in bilingual subjects. The increased attentional control, inhibition, and conflict resolution developed from bilingualism may be accountable for the later onset of dementia. Misdiagnoses as a language impairment There is some research that demonstrates that bilingualism may often be misdiagnosed as a language impairment. A subtopic of bilingualism in the literature is nonstandard varieties of English. While bilingualism and nonstandard varieties of English cannot be considered a true language impairment, they are misrepresented in the population of those receiving language interventions. Language disorders A language disorder is the impaired comprehension and or use of a spoken, written, and/or other symbol system. A disorder may involve problems in the following areas: The form of language i.e. phonology, morphology, or syntax The content i.e. semantics The function of language in communication i.e. pragmatics Olswang and colleagues have identified a series of behaviors in children in the 18–36 month range that are predictors for the need of language intervention. These predictors include: A smaller than average vocabulary A language comprehension delay of 6 months or a comprehension deficit with a large comprehension production gap Phonological problems such as restricted babbling or limited vocalizations Few spontaneous vocal imitations and reliance on direct modeling in imitation tasks Little combinatorial or symbolic play Few communicative or symbolic gestures Behavior problems Some of the many conditions that cause language development problems include: Attention deficit hyperactivity disorder Auditory processing disorder Autism Developmental verbal dyspraxia Language delay Otitis media Pragmatic language impairment Specific language impairment Speech delay Speech disorder Speech sound disorder Speech repetition See also Computational models of language acquisition Errors in early word