HIV-infected or AIDS patients may develop ADC which causes damage to the nervous system. ADC may be caused by some action of the AIDS virus on the nervous system, although similar problems can be caused by other infections because the AIDS virus lowers the body's ability to fight other infections. It is important to determine whether symptoms are due to ADC or to some other infection since treatment varies for different conditions. AZT has been shown to be beneficial to people with ADC although its effectiveness has only been studied in a small number of patients. Studies suggest that higher doses of AZT are more likely to be effective than standard doses in improving symptoms of ADC.