Developmental topographical disorientation

Further information: Topographical disorientation

Developmental Topographical Disorientation, also known as DTD, is caused by the inability to segregate landmarks and derive navigational information from them, navigate through a non-verbal process, or generate cognitive maps. This is a newly discovered cognitive disorder in which patients who do not have brain structural abnormalities, such as lesions, and exhibit symptoms since childhood. Not to be confused with healthy individuals who have a poor sense of direction, DTD patients get lost in very familiar surroundings, such as their house or neighborhood, daily. This disorder could stem from a lack of experience in navigation during development and could present in different degrees of severity.^[1][2]

Case One

A woman in Vancouver, referred to as Pt1, presented with topographical disorientation in absence of any structural lesions. Despite normal cognitive development, she has never been able to orient with in the environment. Further testing showed that she was able to follow route based, landmark based, and verbal directions to reach a destination in an urban environment. In map based testing, the patient was unable to determine the shortest path between two locations on a map, but was able to follow a route traced on a map. The patient was unable to draw a detailed schematic of her house. Although the number of rooms and their locations were accurate, the spatial scaling was distorted.^[1]

Other Cases

F.G. is a normally developed 22 year old male with more severe symptoms than Pt1. He has no medical history of motor, neurological, or cognitive developmental delays or of neurological or psychiatric diseases. He has been unable to find his bearings in an environment since childhood. F.G. is unable to form a cognitive map, identify landmarks, derive verbal instructions used in navigation, retain a previously learned path, or read a map. He is able to accomplish rudimentary navigational tasks, such as those in a virtual environment, by adopting a verbal strategy. F.G. is unable to segregate and identify a landmark in his environment or determine location or directional information from a landmark he recognizes.^[2]

Emergent Disorder

Selective topographical disorientation have been in 120 new cases using an online neuropsychological test.^[3] The participants reported getting lost daily or 1 to 5 times a week in familiar surroundings such as their neighborhood or house and having this difficulty since childhood. They have no other cognitive difficulties that affect daily activities. The test evaluated their object and face recognition ability, landmark recognition, ability to recall directional information, left/right orientation, and ability to reverse a route to return to starting position. The final two tests involved the formation and use of a cognitive map. The test provided objective confirmation of topographical disorientation and preliminary evaluation of different orientation skills. Future research will include in-person testing to further evaluate orientation skills in a real-world environment along with Neuropsychological evaluation and structural imaging to rule out cognitive defects.^[4]

References

1. ^ ^{a b} Iaria, Giuseppe; Bogod, Nicholas; Fox, Christopher J.; Barton, Jason J.S. (2009-01). "Developmental topographical disorientation: Case one". Neuropsychologia 47 (1): 30–40. doi:10.1016/j.neuropsychologia.2008.08.021. PMID 18793658. http://www.neurolab.ca/2009(3)_Iaria.pdf. 
2. ^ ^{a b} Bianchini, F; Incoccia, C; Palermo, L; Piccardi, L; Zompanti, L; Sabatini, U; Peran, Patrice; Guariglia, C. (2010). "Developmental topographical disorientation in a healthy subject". Neuropsychologia 48 (6): 1563–1573. doi:10.1016/j.neuropsychologia.2010.01.025. http://www.neurolab.ca/2009(6)_Incoccia.pdf. 
3. ^ "Getting Lost". University of Calgary. http://gettinglost.ca. 
4. ^ Iaria, Giuseppe; Barton, Jason J.S. (2010). "Developmental topographical disorientation: a newly discovered cognitive disorder". Exp Brain Res 206 (2): 3189–196. doi:10.1007/s00221-010-2256-9. http://www.neurolab.ca/2010(2)_Iaria.pdf. 

External links

• "Orientation Testing". University of Calgary. http://www.orientationtesting.com/. 
• "CTV News Segment". YouTube. http://www.youtube.com/watch?v=AEqFrCYiSEQ. 
• Radiolab episode on woman with DTD