What is a learning disability?

Learning disability (LD) is a term that describes a broad array of possible causes, symptoms, treatments and outcomes. Learning disabilities can show up in many forms, making it difficult to diagnose. They have no known causes and no known cure.

According to the National Institute of Mental Health (NIMH):

LD is a disorder that affects people's ability to either interpret what they see and hear or to link information from different parts of the brain. These limitations can show up in many ways--as specific difficulties with spoken and written language, coordination, self-control or attention. Such difficulties extend to schoolwork and can impede learning to read or write or to do math.

Learning disabilities can last throughout a person's life and affect many aspects, including:

  • School
  • Work
  • Daily routines
  • Personal relationships

Some people have several overlapping learning disabilities, while others may have a single, isolated problem that has little impact on other areas of their lives.

What causes learning disabilities?

Mental health professionals stress that a specific cause of learning disabilities is unknown, and there are too many possibilities to establish a cause with certainty.

Once thought to be caused by a single neurological problem, researchers now say that the causes are more diverse and complex. According to the National Institutes of Mental Health, new evidence seems to show that most learning disabilities do not start in a single, specific area of the brain, but from difficulties in bringing together information from various brain regions.

A leading theory is that learning disabilities stem from subtle disturbances in brain structures and functions that may begin before birth. Other possibilities include:

  • Genetic predisposition
  • Tobacco, alcohol or substance abuse by the mother prior to, during, and after pregnancy
  • Problems during pregnancy or delivery
  • Environment -- both emotional and physical

Different types of learning disabilities:

Learning disabilities are divided into three broad categories, each with more specific designations:

  • Developmental speech and language disorders are usually the first indication that a person has a learning disability.

Signs and symptoms include:

  • Not producing speech sounds
  • Not using spoken language to communicate
  • Not understanding what other people say

Depending on the problem, the specific diagnosis may be:

  • Developmental articulation disorder - problems controlling the rate of speech
  • Developmental expressive language disorder - problems expressing themselves in speech
  • Developmental receptive language disorder - trouble understanding certain aspects of speech

Children with academic skills disorders are behind their classmates in developing reading, writing, or arithmetic skills. The diagnoses in this category include:

  • Developmental reading disorder - also known as dyslexia
  • Developmental writing disorder - involves several brain areas and functions and creates problems in vocabulary, grammar, hand movement, and memory
  • Developmental arithmetic disorder - involves problems with recognizing numbers and symbols, memorizing facts such as the multiplication table, aligning numbers, and understanding abstract concepts like place value and fractions
  • Other - includes certain coordination disorders and learning handicaps not covered by other terms; additional categories such as "motor skills disorders" and "specific developmental disorders not otherwise specified."
  • Attention deficit hyperactivity disorder (ADHD) is not considered to be a learning disability, but since it can affect performance in school, it is often included in the list.

How are learning disabilities diagnosed?

Not all learning problems are necessarily learning disabilities. Children show natural differences in their rate of development, and some are simply slower in developing certain skills. What seems to be a learning disability may simply be a delay in maturation. To be diagnosed as a learning disability, specific criteria must be met.

The NIMH states that:

By law, learning disability is defined as a significant gap between a person's intelligence and the skills the person has achieved at each age.

Criteria and characteristics for diagnosing learning disabilities are listed in a reference book commonly called "the DSM" (Diagnostic and Statistical Manual of Mental Disorders). The actual diagnosis of a learning disability is made by using standardized tests that compare the child's level of ability to what is considered normal development for a person of that age and intelligence.

Each type of learning disability is diagnosed in slightly different ways.

  • Speech and language disorders - a speech therapist tests the pronunciation, vocabulary, and grammar skills; a psychologist tests intelligence; a child's physician checks for ear infections (an audiologist may be consulted to rule out auditory problems) and may examine a child's vocal cords and throat.
  • Academic skills disorders - development in reading, writing and math is evaluated using standardized tests; vision and hearing are also tested.
  • ADHD - diagnosed by checking for the long-term presence of specific behaviors, such as considerable fidgeting, losing things, interrupting, talking excessively, and/or an inability to remain seated, stay on task or take turns.