Agraphesthesia is a disorder of directional cutaneous kinesthesia or a disorientation of the skin's sensation across its space. It is a difficulty recognizing a written number or letter traced on the skin after parietal damage.
Agraphesthesia, or the lack of graphesthesia ability, results from brain damage, particularly to the parietal lobe, thalamus, and secondary somatosensory cortex.
A significant relationship has been found between agraphesthesia and people living with Alzheimer's disease. Alzheimer’s patients typically experience the lack of sensation in both their dominant and non-dominant hands.
Astereognosis, the inability to identify a physical object solely by touch, is commonly found in conjunction with agraphesthesia in Alzheimer’s patients.
Some research suggest that agraphesthesia can be used to track the cognitive decline in Alzheimer’s patients once the disease is diagnosed.
Studies also show that patients diagnosed with schizophrenia and their immediate relatives have a decreased ability to perform graphesthesia tasks in comparison to people without relatives diagnosed with schizophrenia. Therefore, researchers have suggested that somatosensory dysfunction in the parietal cortex is a potential cause of graphesthesia impairments.