Types of Developmental Disabilities: Nervous System, Sensory, Metabolic, and Degenerative

According to the Centers for Disease Control and Prevention (CDC), a developmental disability is an umbrella term for several different types of conditions characterized by impairments in language, learning, behavior, and physical parts of life. Here’s a brief guide for understanding nervous system, sensory, metabolic, and degenerative developmental disabilities and how Integrity, Inc. can help you on your journey to better health and independence.

Types of developmental disabilities

Nervous system

Developmental disabilities that affect the nervous system (also called neurodevelopmental disorders) are characterized by their involvement in the brain or nervous system, spinal column, or the nerves. And when a dysfunction in the brain or nervous system exists, psychological or physical symptoms may result.

Neurodevelopmental disorders vary by the:

  • way that they present
  • symptoms that appear
  • outcomes of the condition
  • complications that may accompany them

Symptoms may include physical, cognitive, behavioral, or emotional repercussions. Some disorders have more than one. These individuals may have difficulty learning, remembering, practicing self control, or managing and experiencing emotions.

Examples of neurodevelopmental disorders include:

  • speech and language disorders
  • attention deficit hyperactivity disorder (ADHD)
  • cerebral palsy
  • autism spectrum disorders
  • learning disorders
  • intellectual disabilities

It’s important to remember that developmental issues begin at a young age. Therapies and treatments may allow the individual to manage problematic symptoms, but neurodevelopmental disorders generally require lifelong management.


Sensory development issues are characterized by the ways that an individual processes sensory information. Generally, those with sensory developmental concerns are assumed to have difficulty handling loud noises or bright lights. However, there are many ways that sensory developmental disorders can present.

Sensory Processing Disorders (SPD), for example, includes a range of processing issues across all the senses. STAR Institute maintains that SPD may occur in “visual, auditory, tactile, smell, taste, vestibular, proprioception, [and] interoception” processing. Moreover, it can also affect more than one system at once and can appear differently for each individual. Some people feel as if they’re being overwhelmed by sensory information. Others, however, may only crave certain sensations.

SPD consists of three types of subcategories: Sensory Modulation Disorder, Sensory-Based Motor Disorder, and Sensory Discrimination Disorder. Each of these types may exhibit a crossover between the different senses, and each type may experience too much or too little sensory responsivity or craving.

It’s also important to know that vision impairment or hearing loss can sometimes be easier to manage. If a child who experiences these impairments begins learning how to navigate without being able to hear or see, they may often thrive in life.


Metabolic developmental disabilities are hundreds of different conditions that develop because of an impediment in the way that the metabolism works, often as a result of genetic defects inherited from both parents.

The metabolism is all the chemical reactions that your body uses to live. It creates energy, gets rid of chemicals that you no longer need, stores chemicals for later use, and uses chemicals in the best way. Together, these things are the metabolic process. And when it doesn’t work just right, many things can go wrong.

The metabolic disorder that develops depends on which genetic defect is present. Hunter syndrome, for example, is a rare disorder in which there’s not enough of a certain enzyme. This ultimately affects the person’s appearance, the way that the organs work, physicality, and mental development.

Krabbe disease is another rare condition but characterized by the destruction of the myelin sheath that protects nerves and nerve cells. Although this disease generally results in early fatalities when it begins in infancy, adults and older children may develop different symptoms. These include:

  • vision loss
  • difficulties walking
  • weak muscles
  • lack of dexterity
  • cognitive decline

Tay-Sachs is a more well-known metabolic disorder in which a lack of an enzyme allows fatty substances called gangliosides to build up in the brain. This build up continues until the patient loses muscle control and eventually experiencing paralysis, vision loss, and death.

Each metabolic disability looks a little different, but they’re all the result of as little as one chemical disruption that completely changes the way that the body and/or brain work. This makes developmental milestones slow to appear or interfere with normal function.


Degenerative disorders are characterized by an initial appearance of normalcy followed by a degeneration of function or ability. Years may pass before some types of degenerative disorders become obvious. Childhood disintegrative disorder (CDD), or Heller’s syndrome, is a characteristic degenerative disorder and sometimes described as a rare form of autism.

Rather than seeing a failure to meet developmental milestones, early milestones appear to be on track with this type. Later, children begin to fail to meet milestones or exhibit a reversal of development, especially in social, motor, or language skills.

These reversals can occur quickly or be drawn out. Sometimes the child seems to know that something is changing internally and shows extreme anxiety over it. However, most children don’t show signs of a problem until around four years old, although some may begin as young as two, and others may be as old as ten.

The cause of CDD is unknown. Although quite rare, it’s the more common degenerative disorder. Degenerative disorders in general result in requiring assistance for everyday functioning for the individual’s entire life.

For more information

Developmental disabilities can present in many ways and often without cause. Knowing this, the staff at Integrity, Inc. aims to help children and adults with developmental disabilities reach appropriate levels of independence and to provide support for them and their families.

If you need more information about how we can help, contact us at (501) 406-0442, or submit this form today.

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