Other factors that may lengthen recovery time after mTBI include psychological problems such as substance abuse or clinical depression, poor health before the injury or additional injuries sustained during it, and life stress. Longer periods of amnesia or loss of consciousness immediately after the injury may indicate longer recovery times from residual symptoms. Other strong factors include participation in a contact sport and body mass size. Pediatric concussion
Most children recovery completely from concussion in less than four weeks, however 15–30% of youth may experience symptoms that last longer than a month. People aged 65+ with concussion
Mild traumatic brain injury recovery time in people over age 65 may have increased complications due to elevated health concerns, or comorbidities. This often results in longer hospitalization duration, poorer cognitive outcomes, and higher mortality rates. Repeat concussion
For unknown reasons, having had one concussion significantly increases a persons risk of having another. Having previously sustained a sports concussion has been found to be a strong factor increasing the likelihood of a concussion in the future. People who have had a concussion seem more susceptible to another one, particularly if the new injury occurs before symptoms from the previous concussion have completely gone away. It is also a negative process if smaller impacts cause the same symptom severity. Repeated concussions may increase a persons risk in later life for dementia, Parkinsons disease, and depression. Post-concussion syndrome
In post-concussion syndrome, symptoms do not resolve for weeks, months, or years after a concussion, and may occasionally be permanent.
Return-to-school
The resumption of low-risk school activities should begin as soon as the student feels ready and has completed an initial period of cognitive rest of no more than 24–48 hours following the acute injury. Long absences from school are not suggested, however, the return to school should be gradual and step-wise. Prolonged complete mental or physical rest (beyond 24–48 hours after the accident that lead to the concussion) may worsen outcomes, however, rushing back to school before the person is ready, has also been associated with longer-lasting symptoms and an extended recovery time. Students with a suspected concussion are required to see a doctor for an initial medical assessment and for suggestions on recovery, however, medical clearance is not required for a student to return to school. Since students may appear normal, continuing education of relevant school personnel may be needed to ensure appropriate accommodations are made such as part-days and extended deadlines. Accommodations should be based on the monitoring of symptoms that are present during the return-to-school transition including headaches, dizziness, vision problems, memory loss, difficulty concentrating, and abnormal behavior. Students must have completely resumed their school activities (without requiring concussion-related academic supports) before returning to full-contact sports. Return-to-sport
For persons participating in athletics, it is suggested that participants progress through a series of graded steps. These steps include:

Immediately after injury: 24–48 hours (maximum) of relative physical and cognitive rest. Stage 1: Gentle daily activities such as walking in the house, gentle housework, and light school work that do not make symptoms worse. No sports activities.