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.
A person afflicted with pica has a persistent craving for a substance that is not commonly considered to be food. The substances that are craved and ingested tend to vary with the person's age. Children with pica may eat glue, animal droppings, sand, insects, leaves, or gravel.Adolescents and adults may consume clay, laundry detergent, or soil.he substances that are craved and ingested tend to vary with the person's age. Children with pica may eat glue, animal droppings, sand, insects, leaves, or gravel. Adolescents and adults may consume clay, laundry detergent, or soil.