 One of the major concerns following acute carbon monoxide poisoning is the severe delayed neurological manifestations that may occur . Problems may include difficulty with higher intellectual functions , short @-@ term memory loss , dementia , amnesia , psychosis , irritability , a strange gait , speech disturbances , Parkinson 's disease @-@ like syndromes , cortical blindness , and a depressed mood . Depression may occur in those who did not have pre @-@ existing depression . These delayed neurological sequelae may occur in up to 50 % of poisoned people after 2 to 40 days . It is difficult to predict who will develop delayed sequelae ; however , advanced age , loss of consciousness while poisoned , and initial neurological abnormalities may increase the chance of developing delayed symptoms . 
