and from the same site you quote, Mainah "The Family Caregiver Alliance" :
Prevention
* Motorcycle helmets provide protection for motorcycle drivers for all types and locations of head injuries, and, contrary to a popular misconception, are not associated with increased neck injuries.21
* Studies indicate that the risk of brain injury in hospitalized motorcyclists is nearly twice that for unhelmeted motorcyclists and that unhelmeted drivers had acute care costs three times ($30,365) that of helmeted drivers 22, 23
* In California, the first year's implementation of the 1992 helmet law resulted in a 37.5% decrease in statewide motorcycle crash fatalities over the previous year; those likely to sustain TBI-related impairments decreased 34%. California has demonstrated a more than 99% compliance rate in helmet use. This suggests that, with adequate enforcement, unrestricted helmet laws can achieve nearly 100% compliance.24, 25, 26
* As many as 74% to 85% of bicycle-related head injuries could be prevented if bike riders were to wear protective helmets. An average of 140,000 head injuries per year are attributed to children and adolescents in bicycle accidents.18, 19
Prevention
* Motorcycle helmets provide protection for motorcycle drivers for all types and locations of head injuries, and, contrary to a popular misconception, are not associated with increased neck injuries.21
* Studies indicate that the risk of brain injury in hospitalized motorcyclists is nearly twice that for unhelmeted motorcyclists and that unhelmeted drivers had acute care costs three times ($30,365) that of helmeted drivers 22, 23
* In California, the first year's implementation of the 1992 helmet law resulted in a 37.5% decrease in statewide motorcycle crash fatalities over the previous year; those likely to sustain TBI-related impairments decreased 34%. California has demonstrated a more than 99% compliance rate in helmet use. This suggests that, with adequate enforcement, unrestricted helmet laws can achieve nearly 100% compliance.24, 25, 26
* As many as 74% to 85% of bicycle-related head injuries could be prevented if bike riders were to wear protective helmets. An average of 140,000 head injuries per year are attributed to children and adolescents in bicycle accidents.18, 19