Functionally, these neurons are either motor (conducting impulses that will cause activity such as the contraction of muscles) or association (conducting impulses and permitting 'communication' between neurons within the central nervous system).
The scant research that has been done on the causes of pica suggests that the disorder is a specific appetite caused by mineral deficiency in many cases, such as iron deficiency, which sometimes is a result of celiac disease or hookworm infection.
Pagophagia is the compulsive consumption of ice or iced drinks. It is a form of the disorder pica. It has been associated with iron deficiency anemia, and shown to respond to iron supplementation, leading some investigators to postulate that some forms of pica may be the result of nutritional deficiency. Chewing ice may lessen pain in glossitis related to iron deficiency anemia.