Why does my intellect fluctuate so much

Intellectual disability


Stephen Brian Sulkes

, MD, Golisano Children's Hospital at Strong, University of Rochester School of Medicine and Dentistry

Last full review / revision May 2020 | Content last changed May 2020
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People with an intellectual disability (ID) have significantly below average intellectual abilities that have existed since birth or early childhood. Their ability to cope with normal everyday tasks is limited.
  • Intellectual disability can be genetic or the result of a disorder that affects the development of the brain.

  • Most intellectually disabled children do not develop clearly recognizable symptoms until they reach preschool.

  • The diagnosis is based on the results of a formal test.

  • Adequate prenatal care reduces the risk of having an intellectually disabled child.

  • With the help of specialists, therapy and special lessons, intellectually disabled children can achieve the highest possible level of function.

The expression used earlier mental disability is increasingly attached to a social stigma, which is why medical professionals are now from intellectual disability speak.

Intellectual disability (ID) is not a specific medical disorder like pneumonia or strep throat, nor is it a mental health disorder. An intellectually disabled person is only able to cope with everyday tasks to a limited extent in one or more areas due to their below-average intellectual performance (adaptive skills), so that they need ongoing support. Adaptive skills can be broken down into several areas, including

  • Conceptual area: memory performance as well as reading, writing and arithmetic skills

  • Social area: awareness of the thoughts and feelings of others, interpersonal skills and social judgment

  • Practical area: personal care, organization of tasks (for school or work), dealing with money, health and safety

Intellectually disabled people are damaged to varying degrees, from slightly to severely disabled. While the disability itself is caused by decreased mental performance (typically measured by standardized intelligence tests), the degree of disability depends primarily on the amount of support the person needs. For example, a person who is only slightly disabled on the intelligence test may have such poor adaptive skills that extensive support is required.

The degree of support is divided into

  • Intermittent: Occasional support is required

  • Limited: support e.g. B. in the form of a day program in a workshop for the disabled

  • Comprehensive: Daily, ongoing support

  • In-depth High level of care in all day-to-day activities, possibly even full-time care

Based on the results of IQ tests alone, around 3 percent of the population have an intellectual disability (IQ less than 70). However, based on the number of people in need of assistance, only about 1 percent of the population has a severe intellectual disability.

Degree of intellectual disability

Skills in preschool age (birth to 6 years)

Adaptive skills at school age (6 to 20 years old)

Required assistance in adulthood (21 years and older)

Often shows delays in speech and language development

Often diagnosed late

Can acquire social and communication skills

Certain reading, writing and arithmetic difficulties, but can reach the level of a primary school certificate in adolescence

Challenges with planning and managing money

Socially immature but can learn adequate social skills

Certain limitations in judgment and risk assessment - more easily manipulated by others

Needs guidance and support in complex tasks (such as health and legal decisions) and in times of strong social or economic pressure

Can usually develop sufficient social and professional skills to lead an independent life

Low social awareness

May benefit from self-employment training

Can learn to speak or communicate

Can achieve elementary school level with support for schoolwork

Learn to move around familiar places by yourself

Social judgment and understanding are limited, but the person affected can learn certain social and professional skills

Can build successful friendships and romantic relationships

Takes care of simple personal needs and household chores following extensive instructions

Needs supervision and support when dealing with money, planning and all slightly more complex everyday tasks

Can lead an independent life as an unskilled or semi-skilled worker in a supportive environment

Can cope with his basic needs himself to a certain extent

Has limited language skills

Can speak a few words

Can speak or learn to discuss simple, everyday events and can learn simple health behaviors

Little understanding of written language, numbers, time, or money

Benefits from behavior training

Usually successful relationships with family members and known confidants

Sometimes inappropriate behavior (including self-harm)

Can develop some useful self-protection techniques in a sheltered environment

Needs support with all everyday tasks, but can sometimes take care of himself under constant supervision

Must be cared for due to limited self-sufficiency

Extreme cognitive limitation

Often sensory and / or physical disabilities

Limited understanding of language or gestures, mainly communicates non-verbally

Enjoy the company of familiar family members and caregivers, but the sensory and physical disabilities often limit social activities

Often in need of maintenance

Self-sufficiency is only possible to a very limited extent


A number of medical and environmental factors can cause intellectual disability. Some diseases are genetic. already present before or at the time of conception. Other factors occur during pregnancy or during or after childbirth. What all factors have in common is that they impair the growth and development of the brain. Even with the latest advances in genetics, particularly in chromosome analysis techniques, a specific cause of intellectual disability can often not be identified.

Some causes that before or during conception can occur are:

Some causes that during pregnancy can occur are:

Some causes that during birth can occur are:

Some causes that after birth can occur are: