Individuals with mild to moderate intellectual disabilities exhibit warning signs very similar to those of individuals with normal intellectual functioning, although these can be more complex to identify due to difficulties in verbal expression and the diagnostic overlap caused by intellectual disability. These warning signs precede psychotic symptoms (they may begin a few days or even weeks earlier) and are crucial for providing early intervention for psychosis.

In cases of individuals with moderate to severe intellectual disability , warning signs focus more on changes in baseline behavioral patterns and are often associated with challenging behaviors. Some of these signs may include :

• High psychophysical anxiety.
• Self- or hetero-aggression.
• Destruction of objects.
• Atypical habits.
• Worsening of repetitive behaviors.
• Behaviors related to withdrawal or negativism.
• Loss of learned skills.
• A feeling of dread or fear.
• Disruption of the sleep-wake cycle.
• Impact on food intake.

People with intellectual disabilities are three times more likely to have this disorder compared to the general population.