Intellectual impairment
| Developmental Disability | |
|---|---|
| Classification and external resources | |
| Specialty | Psychiatry |
| MeSH | D002658 |
Developmental disability is a diverse group of chronic conditions that are due to mental or physical impairments. Developmental disabilities cause individuals living with them many difficulties in certain areas of life, especially in "language, mobility, learning, self-help, and independent living". Developmental disabilities can be detected early on, and do persist throughout an individual's lifespan. Developmental disability that affects all areas of a child's development is sometimes referred to as global developmental delay.
Most common developmental disabilities:
The causes of developmental disabilities are varied and remain unknown in a large proportion of cases. Even in cases of known etiology the line between "cause" and "effect" is not always clear, leading to difficulty in categorizing causes.
Genetic factors have long been implicated in the causation of developmental disabilities. There is also a large environmental component to these conditions, and the relative contributions of nature versus nurture have been debated for decades.
Current theories on causation focus on genetic factors, and over 1,000 known genetic conditions include developmental disabilities as a symptom.
Developmental disabilities affect between 1 and 2% of the population in most western countries, although many government sources acknowledge that statistics are flawed in this area. The worldwide proportion of people with developmental disabilities is believed to be approximately 1.4%. It is twice as common in males as in females, and some researchers have found that the prevalence of mild developmental disabilities is likely to be higher in areas of poverty and deprivation, and among people of certain ethnicities.
Developmental disabilities can be initially suspected when a child does not reach expected child development stages. Subsequently, a differential diagnosis may be used to diagnose an underlying disease, which may include a physical examination and genetic tests.
The degree of disability can be quantified by assigning a developmental age to a person, which is age of the group into which test scores place the person. This, in turn, can be used to calculate a developmental quotient (DQ) as follows:
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