Nerve damage due to poor blood circulation or a neurological disorder is often the cause of numbness in the tip of an index finger, states Mayo Clinic. Conditions such as carpal tunnel syndrome, diabetes and multiple sclerosis are common causes of this type of numbness, also known as peripheral neuropathy.
Numbness of the tip of an index finger is often a sign of a greater medical issue such as nerve damage or a neurological disorder. Carpal tunnel syndrome, which causes irritation of the nerves in the hand and wrist, is a common culprit of a tingling sensation or numbness of fingertips, according to Medicine Net. Rheumatoid arthritis, a condition in which nerves in joints are inflamed, also causes numbness of index fingers. Both conditions are chronic, and their symptoms present themselves randomly, although a change in weather is known as a contributing factor.
One of the long-term side effects of diabetes is poor blood circulation. This, in turn, can cause fingertips to become numb, notes Mayo Clinic. Poor blood circulation cuts off the blood flow to a person's extremities.
Another cause of the numbness of fingertips is frostbite. When skin is exposed to below-freezing temperatures, the cold causes blood circulation to slow and nerves to become numb.
Autoimmune diseases such as AIDS, lupus and multiple sclerosis can result in the numbness of extremities, according to PDR Health. In cases of autoimmune diseases, the link between the brain and nervous system deteriorates over time, causing nerves to become numb. The first signs of this symptom, also known as neuropathy, occurs in the fingertips.