Menu Types of Intellectual Impairments - Disability Info SA

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Intellectual Impairments are also referred to as Intellectual disability (ID), or intellectual development disorder (IDD). It affects about 2–3% of the general population, about a quarter of these cases are caused by a genetic disorder. Cases of unknown causes affect about 95 million people as of 2013.

For the purposes of this web site, we have subdivided Intellectual disability into Developmental Disabilities & Mental Disabilities.

  • 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". Examples of Developmental Disabilities include Autism, Down Syndrome & Dyslexia, among others.
  • Mental Disabilities or illnesses refers to a wide range of mental health conditions or disorders that affect your mood, thinking and behavior. Examples of mental illness include depression, anxiety disorders, schizophrenia, eating disorders and addictive behaviors. Many people have mental health concerns from time to time.

Below are a List of Intellectual Impairments under their Sub-categories. To view more information about these Intellectual Impairments, and others, view the menu on the left.

Developmental Disabilities


Attention Deficit Hyperactivity Disorder (ADHD), is also known as Attention Deficit Disorder (ADD), though this is considered an outdated term. ADHD is a neurodevelopmental and mental disorder & is characterized by problems paying attention, excessive activity, or difficulty controlling behavior which is not appropriate for a person's age. These symptoms begin by age six to twelve and persist for more than six months.

ADHD is one of the most common childhood disorders & may result in poor school performance due to problems paying attention. Although many children have a good attention span for tasks they find interesting. The condition can vary from person to person.

Despite being the most commonly studied and diagnosed psychiatric disorder in children and adolescents, the cause is unknown in the majority of cases. The World Health Organization estimated that it affected about 39 million people as of 2013.

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Asperger Syndrome

Asperger syndrome (AS) is a developmental disorder characterized by significant difficulties in social interaction & nonverbal communication, along with restricted & repetitive patterns of behavior & interests. It is an autism spectrum disorder (ASD) & differs from other disorders by relatively normal language and intelligence. Although not required for diagnosis, physical clumsiness & unusual use of language are common. Symptoms usually begin before two years old & can last for a person's entire life.

The exact cause of Asperger's is unknown. While there is likely a genetic basis it has not been determined. Environmental factors are also believed to play a role. There is no single treatment, & the effectiveness of particular interventions is supported by only limited data.

Treatment is aimed at improving:

  • poor communication skills
  • obsessive or repetitive routines
  • physical clumsiness.

Treatment efforts include:

  • social skills training
  • cognitive behavioral therapy
  • physical therapy
  • speech therapy
  • parenting training
  • medications for associated problems such as depression or anxiety.

Most children improve as they grow up, but social and communication difficulties may persist.

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Autism is a neuro developmental disorder characterized by impaired social interaction, verbal and non-verbal communication, and restricted and repetitive behavior. Parents usually notice signs in the first two years of their child's life. These signs often develop gradually, though some children with autism reach their developmental milestones at a normal pace and then regress. The diagnostic criteria require that symptoms become apparent in early childhood, typically before age three. Globally, autism is estimated to affect 21.7 million people as of 2013. It occurs four to five times more often in boys than girls.

While autism is often inherited, researchers suspect both environmental & genetic factors as causes. In rare cases, autism is associated with agents that cause birth defects. Autism affects information processing in the brain by altering how nerve cells & their synapses connect & organize.

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Down syndrome

Down syndrome (DS or DNS), also known as Trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is typically associated with physical growth delays, characteristic facial features, and mild to moderate intellectual disability. The average IQ of a young adult with Down syndrome is 50, equivalent to the mental age of an 8 or 9-year-old child, but this can vary.

The parents of the affected individual are typically genetically normal. The extra chromosome occurs by random chance. There is no known behavior or environmental factor that changes the risk. Down syndrome can be identified during pregnancy by prenatal screening followed by diagnostic testing, or after birth by direct observation & genetic testing. Regular screening for health problems common in Down syndrome is recommended throughout the person's life. There is no cure for Down syndrome.

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Dyslexia, also known as reading disorder, is characterized by trouble with reading unrelated to problems with overall intelligence. People are affected to varying degrees. There is no cure for Dyslexia, however it can help if teaching methods are adjusted to meet the person's needs. While not curing the underlying problem, it may decrease the degree of symptoms. Treatments targeting vision are not effective.

Dyslexia is the most common learning disability, affecting 3–7 % of the population; however, up to 20% may have some degree of symptoms. While dyslexia is more often diagnosed in men, it is thought to affect men & women equally. Dyslexia occurs in all areas of the world. Some believe that dyslexia should be best considered as a different way of learning.

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Mental Disabilities

Alzheimer's Disease

Alzheimer's disease (AD), also known as Alzheimer's, accounts for 60% to 70% of cases of dementia. It is a chronic neurodegenerative disease that usually starts slowly and gets worse over time. The cause of Alzheimer's disease is not clear, but about 70% of the risk is believed to be genetic. Other risk factors include a history of head injuries, depression, or hypertension.

In 2015, there were approximately 48 million people worldwide with AD. It most often begins in people over 65 years of age, although 4% to 5% of cases are early-onset Alzheimer's which begin before this. It affects about 6% of people 65 years and older.

The most common early symptom is difficulty in remembering recent events (short-term memory loss). As the disease advances, symptoms increase, they can include:

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Anxiety Disorder

Anxiety disorders are a category of mental disorders characterized by feelings of anxiety and fear, where anxiety is a worry about future events and fear is a reaction to current events. These feelings may cause physical symptoms, such as a racing heart and shakiness.

Anxiety disorders are partly genetic but may also be due to drug use including alcohol & caffeine, as well as withdrawal from certain drugs. They often occur with other mental disorders, particularly major depressive disorder, bipolar disorder, certain personality disorders, and eating disorders. The term anxiety covers four aspects of experiences that an individual may have: mental apprehension, physical tension, physical symptoms and dissociative anxiety. The emotions present in anxiety disorders range from simple nervousness to bouts of terror. There are other psychiatric and medical problems that may mimic the symptoms of an anxiety disorder, such as hyperthyroidism.

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Bipolar Disorder

Bipolar disorder is a mental illness characterized by periods of depression and periods of elevated mood. The elevated mood is significant and is known as mania or hypomania depending on its severity or whether symptoms of psychosis are present. During mania an individual behaves or feels abnormally energetic, happy or irritable. Individuals often make poorly thought out decisions with little regard to the consequences. The need for sleep is usually reduced during manic phases as well. During periods of depression there may be crying, a negative outlook on life, and poor eye contact with others. The risk of suicide among those with the illness is high at greater than 6% over 20 years, while self-harm occurs in 30-40%. Other mental health issues such as anxiety disorder and substance use disorder are commonly associated.

About 1% of people around the world are estimated to have bipolar disorder at some point in their life. The most common age at which symptoms begin is 25. Rates appear to be similar in females as males. People with bipolar disorder often face problems with social stigma. The cause is not clearly understood, but both environmental and genetic factors play a role. Environmental factors include a history of childhood abuse and long term stress.

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Depression is a state of low mood and aversion to activity that can affect a person's thoughts, behavior, feelings and sense of well-being. Depressed mood is a feature of some psychiatric syndromes such as major depressive disorder, but it may also be a normal reaction to life events such as bereavement, a symptom of some bodily ailments or a side effect of some drugs and medical treatments. Women have a higher rate of major depression than men. While women have a greater proportion of somatic symptoms, such as appetite, sleep disturbances and fatigue accompanied by pain and anxiety, than men. Instances of suicide in men is much greater than in women.

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Learning Disabilities

Learning disability is a classification that includes several areas of functioning in which a person has difficulty learning in a typical manner, usually caused by an unknown factor or factors. Given the "difficulty learning in a typical manner", this does not exclude the ability to learn in a different manner. Therefore, some people can be more accurately described as having a "Learning Difference", thus avoiding any misconception of being disabled with a lack of ability to learn and possible negative stereotyping.

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Memory Loss

Memory Loss, also known as Amnesia or amnesic syndrome, is a loss of memory caused by brain damage, disease, or psychological trauma. Amnesia can also be caused temporarily by the use of various sedatives and hypnotic drugs. The memory can be either wholly or partially lost due to the extent of damage that was caused.

Case studies also show that amnesia is typically associated with damage to the medial temporal lobe. In addition, specific areas of the hippocampus (the CA1 region) are involved with memory. Research has also shown that when areas of the diencephalon are damaged, amnesia can occur.

There are two main types of amnesia: Retrograde amnesia and Anterograde amnesia.

  • Retrograde amnesia is the inability to retrieve information that was acquired before a particular date, usually the date of an accident or operation. In some cases the memory loss can extend back decades, while in others the person may lose only a few months of memory.
  • Anterograde amnesia is the inability to transfer new information from the short-term store into the long-term store. People with this type of amnesia cannot remember things for long periods of time.

These two types are not mutually exclusive. Both can occur within a patient at one time. Case studies, such as that of patient R.B., show that both types of amnesia can occur simultaneously.

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Obsessive Compulsive Disorder (OCD)

Obsessive–compulsive disorder (OCD) is a mental disorder where people feel the need to check things repeatedly, perform certain routines repeatedly, or have certain thoughts repeatedly. People are unable to control either the thoughts or the activities. Common activities include hand washing, counting of things, and checking to see if a door is locked. Some may have difficulty throwing things out. These activities occur to such a degree that the person's daily life is negatively affected. Often they take up more than an hour a day. Most adults realize that the behaviors do not make sense. The condition is associated with tics, anxiety disorder, and an increased risk of suicide.

Obsessive–compulsive disorder affects about 2.3% of people at some point in their life. Rates during a given year are about 1.2% and it occurs worldwide. It is unusual for symptoms to begin after the age of thirty-five and half of people develop problems before twenty. Males and females are affected about equally.

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Schizophrenia is a mental disorder characterized by abnormal social behavior and failure to understand reality. Common symptoms include false beliefs, unclear or confused thinking, hearing voices, reduced social engagement and emotional expression, and a lack of motivation. People often have additional mental health problems such as anxiety disorders, major depressive illness or substance use disorder. Symptoms typically come on gradually, begin in young adulthood, and last a long time.

In 2013 there was estimated to be 23.6 million cases globally. About 20% of people do well and a few recover completely. Social problems, such as long-term unemployment, poverty, and homelessness are common. The average life expectancy of people with the disorder is ten to twenty five years less than the average. This is the result of increased physical health problems and a higher suicide rate (about 5%). In 2013 an estimated 16,000 people died from behavior related-to or caused by schizophrenia. Males are more often affected than females.

The cause of schizophrenia is believed to be a combination of environmental and genetic factors.

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A phobia is a type of anxiety disorder, which is usually defined by an intense fear of something that, in reality, poses little or no actual danger. It is normal and even helpful to experience fear in dangerous situations. Fear is an adaptive human response. It serves a protective purpose, but with phobias the threat is greatly exaggerated or nonexistent. For example, it is only natural to be afraid of a snarling Doberman, but it is irrational to be terrified of a friendly poodle on a leash, as you might be if you have a dog phobia.

Common phobias and fears include closed-in places, heights, highway driving, flying insects, snakes, and needles. However, we can develop phobias of virtually anything. Most phobias develop in childhood, but they can also develop in adults.

Phobias are categorized into Specific Phobias & Social Phobias.

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