Organic retardation is primarily caused by:

Organic retardation, often referred to as intellectual disability, primarily stems from genetic disorders or brain damage. This form of retardation is associated with identifiable biological factors that affect cognitive functioning and development. For instance, conditions such as Down syndrome, fetal alcohol syndrome, or birth injuries due to lack of oxygen are examples of how genetic and physiological influences can lead to significant impacts on a person's cognitive abilities.

In contrast to organic retardation, environmental factors, while they can influence cognitive development, do not have the same direct and measurable effects as genetic disorders or brain damage. Poor education and psychological stress may affect a person's functioning or learning potential but are not classified as organic causes of intellectual disabilities.