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Learning disability

In broad terms, the phrase learning disability covers any of a range of
conditions that affect a person's ability to learn new information. These
conditions all affect the brain in some fashion. The most common causes are:

   * defects or errors in brain structure
   * lack of communication between various parts of the brain
   * incorrect quantities of various neurotransmitters, or problems in the
     brain's use of these transmitters
        o common neurotransmitter problems include insufficient dopamine,
          improper serotonin regulation, and excessive dopamine reuptake
          where emitting neurons reabsorb too much dopamine after releasing
          them to communicate with other neurons (also implicated in
          depression).

Major afflictions that impair learning

Down syndrome, or Trisomy 21

     Ultimately caused by an extra chromosome in the genetic makeup of the
     sufferer. One of the primary consequences of the extra chromosome is
     mild to severe mental retardation. Other genetic conditions with
     similar consequences include Trisomy 13 and Fragile X Syndrome.

Dyslexia

     This condition has several forms in varying degrees of severity. The
     three primary forms are
        o difficulty in phonetic mapping, where sufferers have difficulty
          with matching various orthographic representations to specific
          sounds
             o difficulty with spatial orientation, which is stereotyped in
          the confusion of the letters  and , as well as other pairs.
          In its severest form,    and , all distinguished
          primarily by orientation in handwriting, look identical to the
          dyslexic
             o difficulty with sequential ordering, such that a person can
          see a combination of letters and recognize what word it
          corresponds to with the help of phonetic mapping, but cannot
          properly sequence the letters when spelling words.
     Dyslexia has obvious effects on the ability to learn to read and/or
     write, as well as more subtle effects on processing visual information

Language processing disorders

     These are poorly-studied, but have clear effects on learning. Effects
     can be semantic, syntactic or analytical, or can resemble aphasias.
     Some people have difficulty with planning, sequencing, using inductive
     logic, or with verbal expression. All can interfere with learning, at
     both the input and output phases of the process.

Attention Deficit Hyperactivity Disorder (ADD and ADHD)

     AD(H)D sufferers have difficulty in intiating and maintaining
     concentration. The underlying neurological causes are not always clear.
     It also appears that many persons labeled as ADD/ADHD either suffer
     from other problems, or have not had the thorough neruological analysis
     needed to help manage their condition.

Alzheimer's disease

     A condition of the elderly, in which the ability to retain new
     information is lost. As the condition progresses, the patient begins
     losing lifelong memories, with the most recent to go first. Eventually,
     they often regress to childhood, and have such poor memory that they
     cannot perform simple tasks such as walking from one room to another
     because they forget where they are going en route.

Brain injury

     This has multiple causes, and consequently, multiple effects. A few
     common ones are:
          Stroke - can lead to aphasia
          Damage to the brain tissue - effect depends on what area of the
          brain is injured
          Lesions and Tumors - effect depends on what area is injured.
          Dysgraphia - inability to write, regardless of ability to read

Color blindness

     While not a true learning disability, it affects the ability to
     perceive visual information. When such information is presented in a
     way that is confusing to the color-blind, learning is compromised.

Physical handicaps can also impede learning when proper accommodations are not made.

     Blindness interferes with the ability to process visual information, so
     information must be presented in tactile or auditory form to be learnt.
     Deafness and hearing impairment interfere with the ability to process
     auditory information. Information presented in auditory format is
     meaningless to the deaf, and not properly perceived by the hearing
     impaired. Learning occurs best when accommodation is made by providing
     visual and tactile means for acquiring information, as well as
     providing Sign Language interpreters where needed.