What are the four levels of mental retardation?

Intellectual disability is generally classified into four levels: mild intellectual disability, moderate intellectual disability, severe intellectual disability, and profound intellectual disability. The specific details are as follows:

1. Mild intellectual disability: IQ ranges from 50 to 69. Individuals show slightly delayed development in early childhood, with acceptable language expression and comprehension abilities. They can acquire basic life skills and learn simple academic content. As adults, they can perform simple physical labor and adapt to social life with guidance, although their ability to handle complex problems is weak and learning new tasks is slow.

2. Moderate intellectual disability: IQ ranges from 35 to 49. Development is significantly delayed during childhood. Language ability is limited, allowing only simple communication, and systematic academic knowledge is difficult to master. Daily living requires partial assistance from others (e.g., dressing, shopping). As adults, they may engage in simple, repetitive work under supervision but cannot independently manage complex social environments.

3. Severe intellectual disability: IQ ranges from 20 to 34. Development is severely delayed, with poor language function—most individuals can only produce simple sounds and have almost no ability to understand written language. They are completely dependent on others for daily care, unable to feed or dress themselves or move independently. This level is often associated with physical deformities or neurological disorders, and there is a complete lack of social adaptive capacity.

4. Profound intellectual disability: IQ below 20. Marked developmental abnormalities are evident from birth. There is no functional language, and individuals cannot understand any instructions or commands. Motor difficulties are prominent, often accompanied by severe physical illnesses or disabilities. Long-term bed rest or specialized care is required, life expectancy may be reduced, and there is no capacity for independent living or social adaptation.

If a child is observed to have developmental delays, or lags in language or cognitive abilities, an evaluation at a professional institution should be sought as early as possible. Early intervention and training can significantly improve the individual's quality of life and adaptive skills. Family members should provide patient care and support to help the individual better integrate into daily life.