Types Of Developmental Disabilities

When we talk of developmental disabilities, we mean birth defects that involve a problem with how a part of the body or body system functions. Known also as functional birth defects, developmental disabilities affect several body parts or systems. Developmental disabilities can be of many types including nervous system disabilities, sensory related disabilities, metabolic disorders and degenerative disorders.

Nervous system disabilities are birth defects that affect the functioning of the brain, spinal cord, and nervous system. Such disabilities can affect learning and intelligence. These disabilities create problems like behavioral disorders, speech or language difficulties, convulsions, and movement disorders.

Among familiar nervous system disabilities are mental retardation and autism spectrum disorders. Mental retardation, in which victims have lower intelligence levels than average, is caused among other factors by Down Syndrome and Fragile X Syndrome. Down syndrome means a set of mental and physical characteristics related to having an additional copy of Chromosome 21. The most familiar inherited form of mental retardation is Fragile X Syndrome which is caused by a deficiency in a particular part of the Fragile X Mental Retardation-1 gene. This reduces the body's capacity to produce a certain protein without which the brain cannot develop normally.

Autism spectrum disorders consist of a range of problems that can adversely affect a person's communication skills, social skills, and intelligence. People with autism, both children and adults, face difficulties in verbal and non-verbal communication, social interactions, and leisure activities. The severity of this condition may vary from mild to severe.

Sensory-related disabilities are mostly a part of complex birth defect patterns. For example, kids with congenital rubella may be deaf, or develop cataracts of the eyes.

Those who have Williams Syndrome find it difficult to see spatial relationships between objects around them. Those who have Fragile X syndrome are found to be extremely sensitive to loud noises, and may react vehemently to such noises.

Metabolic disorders, a type of functional birth defects, affect a person's metabolism, which holds the key to the growth and development of the human body. Two familiar metabolic disorders are phenylketonuria (PKU) and hypothyroidism. PKU is caused by a problem with a particular enzyme, a protein that speeds up certain chemical reactions, leads to mental retardation. Hypothyroidism is a hormonal condition that can lead to mental retardation if left untreated in a child.

Children who are born with degenerative disorders sometimes appear normal at birth, but then lose abilities or functions because of the condition. In such instances, the defect remains undetected until an older age, when the child or adult starts showing indications of loss of function. Some degenerative disorders are caused by metabolic disorders.

Degenerative disorders can result in physical, mental, and sensory problems, depending on the particular defect. Rett syndrome is a type of degenerative birth defect that more often than not affects girls, and is caused usually by a specific genetic abnormality.

We now often find children with developmental disabilities such as cerebral palsy and epilepsy. Those having cerebral palsy find it hard to talk, see, hear, sit or swallow. However, many people with cerebral palsy are found to possess normal intelligence. People with epilepsy have seizures, varying from momentary disruption of the senses, to short periods of unconsciousness or convulsions.