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Environmental Dependency Syndrome[edit]

Environmental Dependency Syndrome (EDS) is a neurobehavioral disorder in which patients display an exaggerated dependency on the environment for behavioural cues. [1] Depending on their environment, patients will change their behaviour by acting in a way they think is best suited for the environment they are in. For example, if a patient is told that he is in an art gallery, he will start to look at pictures hung on the wall and interpret them as if in an actual art gallery.[2] This behaviour is a result of a lesion to the frontal lobe where patients have been described as being “pulled to stimulus.”[3][4] Among the many functions of the frontal lobe is the inhibition of inappropriate motor, limbic and spatial responses which might impulsively be released as a reaction to various stimuli.[5] This “pull to stimulus” is seen in infants, but as the frontal lobe matures, these instinctive reflexes are inhibited and they can control these urges when interacting in their environment.[5] Patients with EDS have no control over this inhibition and believe it is necessary to utilize and imitate the stimuli in their surroundings.

Classifications[edit]

  • Environmental dependency syndrome is studied as a disorder in the neuroscience and behavioural aspects of cognitive science. It deals with irregular brain functioning resulting in irregular behaviour. It is more specifically classified as a specialized frontal lobe disorder in which all patients exhibiting this behaviour have damage or lesions to their left or right frontal lobe. This results in an imbalance between dependence on and independence from external stimuli.[6] EDS can also be classified as a complex version of utilization behaviour (UB) which involves patients grabbing objects in view and performing the appropriate behaviour with it at an inappropriate time.[7] In this case, the presence of an object compels the patient to either grasp or use the object even when they are asked not to or told to stop. The use of objects at an inappropriate time is seen in almost every, if not all cases of environmental dependency syndrome.
  • A milder version of utilization behaviour, called imitation behaviour (IB), is also observed in EDS patients. Here, patients imitate gestures and behaviours of the examiner even when they are asked not to. The sight of a movement is perceived in the patients mind as an order to imitate it.[8] This may be seen if for example, the experimenter claps his hands and yawns, the patient would perform the same gestures in the same order.

History[edit]

The first experiment to conduct research strictly on environmental dependency syndrome was computed in 1983 by Dr. Jean Lhermitte. Previous studies have touched upon the idea of EDS, but it was Dr.Lhermitte who coined the definition of this syndrome. It was also thought before the conduction of his study that EDS was involuntary.[9] After observing the patients in his study behave voluntarily, this notion was proved incorrect.[1] He had extensively researched utilization behaviour in the lab and wanted to observe such behaviour in a natural setting. He hypothesized that UB and IB would be more apparent when subjects were in environments that are more complex than an experiment situation and that is exactly what he found. Instead of simply using an object for its purpose or imitating someone’s gestures, the subjects took on a role that best fit their knowledge of the environment. For example when entering a bar, the subject immediately took on the role of a bartender and started taking peoples orders and making the drinks. He observed the subjects in various environments and their behaviour in each setting is represented in the table below.

Environment Behaviour
Doctors Office Both patients used almost every tool in the office to their best knowledge on the experimenter as if they themselves were doctors.
Buffet Patient 1 behaved like a guest and waited for food to be brought to him. Patient 2 unstacked chairs and glasses that were not needed to be unstacked and offered the experimenter food as if she was a waitress.
Garden Both patients began to groom and maintain the garden as though it was their responsibility. The experimenter had with him water bottles to drink but the participants took those bottles without saying a word and watered the flowers.
Museum The experimenter had the subjects at his house. He then later told them his house was a museum. Both patients began to walk around his house as if they were in a museum admiring and interpreting the pictures and figurines throughout his home.
House with household items The experimenter presented the male subject with a gun and bullets. He immediately started assembling the gun. The experimenter presented makeup to the female subject and she immediately began to put on the makeup.
Bedroom In the experimenters bedroom, his bed was unmade so Patient 1 undressed and climbed into bed as though they were going to sleep. Patient 2 began to tuck in the covers and make the bed as if they were a housekeeper.

Symptoms[edit]

Patients with environmental dependency syndrome will display similar behaviour to utilization and imitation behaviour. Difference being, EDS is observed in a natural and social environment as opposed to an experimental setting. Objects in the environment and/or the context of the situation appear to demand action on the part of the patient despite the inappropriate nature of their actions.[1] Like in the example presented in the table above, when placed in a bedroom, patients can be seen to undress themselves, climb into a bed regardless if it is theirs, and prepare themselves for sleep. Patients are unable to refrain from the behaviour but feel their actions are normal and they are doing nothing out of the ordinary.

Treatment[edit]

Environmental dependency syndrome has not been effectively studied and has only recently emerged. For this reason, there are currently no formal treatment studies, nor are there any formal, normative based assessments available for the presence and/or severity of the syndrome.[1]

Possible Causes[edit]

As previously stated, EDS has not been adequately researched or experimented on and therefore the following causes are considered possible causes until more research has been conducted:

Frontal Lobe Lesion[edit]

EDS is a subordinate frontal lobe syndrome in which there is damage to the left or right frontal lobe. Damage to the lobe could be a result of a head injury, seizures or any other disorder that affects the frontal lobe.[1] The lesion corresponds to a disorganization of the brains ability to inhibit inappropriate behaviour in their immediate environments.[5] Although spontaneous, this behaviour is not involuntary. Patients actually think that the objects in view are meant to be used and they need to take on a role that the environment is demanding of them. Damage to this area has been proven to be a primary cause of EDS, but the exact location within the lobe is still unknown.

Psychological Features[edit]

In coalition with the biological causes, it is suggested that there are psychological causes as well. The idea of ‘mental inertia’ is suggested to cause the odd behaviour in which they are powerless against the influences of the outside world. They believe that it is their duty to carry out these actions and their decision is not one they make on their own.[1] Their behaviour does not embarrass them however, nor do they think believe it to be odd and this is said to be a result of a loss of self-criticism. Loss of self-criticism is displayed in one patient whom removed her blouse and brassier at the sight of a stethoscope knowing that the clothes would hinder the use of the device.[1]

Social Features[edit]

The social class from where the patients come from also affects the kind of behaviour they display in the various environments.[1] For example, a patient who comes from a high class would take on the role of a guest at a buffet expecting to be served, whereas someone of lower class, would take on the role of a waitress. Objects in their immediate surrounding therefore function as triggers for certain behaviors, predetermined by the individual’s social background.

Loss of Autonomy[edit]

Autonomy is having the right or power of self-government where one can freely determine the laws by which they abide by.[10] EDS is therefore a loss of autonomy. When a patient is introduced to an environment, they consider the social and physical cues as ‘rules’ that they must follow in order to behave as the environment demands them to. For example, if they were to see a chair, they would feel the need to sit on the chair or if they were to see a toothbrush, they would feel obligated to brush their teeth. This loss of autonomy is thought to be result of the lesion to the frontal lobe where the inhibition to follow these ‘rules’ is no longer functioning. Where normal people would be able to inhibit the need to sit on the chair, patients with EDS would not be able to resist the action of sitting on the chair. It is impossible to pinpoint the nervous system organization that allows one to be autonomous because it is not a physiological function. This idea of loss autonomy thus continues to only be a possible cause to this phenomenon.

Types of EDS[edit]

Transient Environmental Dependency Syndrome[edit]

This temporary version of EDS was observed in a 23 year old college student who went out on a jog but was found later in a stranger’s house cleaning and tidying it. She had never displayed anything like this before and her behaviour only lasted for one hour. Her neurological exam was normal and she had never had any head injuries nor seizures. She was however taking phendimetrazine tatrate to induce rapid weight loss which caused a frontal network disturbance.[11] After this episode she no longer took the pills and she never showed any signs of EDS again. Although very temporary, her behaviour was described as a loss of personal autonomy which links it directly to EDS.[1]

Forced Hyperphasia and EDS[edit]

Forced Hyperphasia is a language related fragment of EDS which involves compulsive, environmentally dependent speaking.[5] This type of EDS was observed in an elderly women who was unable to prevent herself from speaking about objects or events in her environment, even though she was asked not to. For example if the doctor were to touch his chin, the patient would scream, “the doctor is touching his chin!” This resembles a syndrome of compulsive writing called forced hypergraphia[12] which is where the name was derived from.[13] She had frontal lobe damage which lead to the inability to respond appropriately without announcing events taking place in her surroundings.[1]

Zelig-like Syndrome[edit]

Here the patient would assume the most relevant job position in whichever context he was in. When he was taken to a bar, he assumed the role of a bartender and when taken to a kitchen, he said that he was a chef and described all the wonderful meals he could cook. He demonstrated a loss of frontal inhibition over the control of his own identity and was attracted towards the social role.[14] His condition recalls Zelig, the mythical Woody Allen character affected by a similar unusual disease in which the name derived from. [15] Who he presented himself to be depended on the kind of working environment he was in and which role he knew best to imitate.

Oral Spelling Behaviour[edit]

If a patient is displaying Oral Spelling Behaviour (OBS) they are spontaneously spelling words out loud based on words they hear and words they read.[16] These patients have a lesion to their frontal lobe where activation to inhibit the spelling out loud is no longer working. This type of behaviour can be compared to multilingual patients with dementia where there is parallel activation of concurrent languages.[17][18] This parallel activation then leads to the loss of inhibition of one language over the other,[17][18] which is similar to what we see in OBS. In OBS they utilize the stimuli around them, pronounce the word out loud and then proceed to spell it.[16] An example of someone suffering from this was an elderly woman who had a lesion to her left prefrontal lobe as result of vascular dementia. She would spell anything she read out loud whether it was a restroom bed panel, book or newspaper. This behaviour only lasted for a short time but reappeared one year later.

Future Research[edit]

Future research would be beneficial to better understand the causes and to discover treatments and evaluations of EDS. Since this syndrome is not very common, Dr.Lhermitte suggested observing the behaviour of monkeys in relation to EDS.[1] He noted that monkeys have been subjected to experiments in which they were led to make a decision involving the outside world and to organize a context dependent behaviour. Environmental dependency syndrome along with utlization behaviour and imitation behaviour have never been measured in such experiments. Conducting an experiment with UB and IB as the focal point, would lead to more information relating to EDS and perhaps a better understanding on how to assess human beings suffering from EDS.

References[edit]

  1. ^ a b c d e f g h i j k L'Hermitte F: Human autonomy and the frontal lobes, part II: patient behavior in complex and social situations: the environmental dependency syndrome. Ann Neurol 1986; 19:335-343.
  2. ^ Archibald, S. J., Mateer, C. A., & Kerns, K. A. (2001)Utilization behavior: Clinical manifestations and neurological mechanisms. Neuropsychology Review, 11(3), 117-130.
  3. ^ Hecaen H, Albert ML. Human neuropsychology. New York: Wiley, 1978.
  4. ^ Stuss DT, Benson DF. The frontal lobes. New York: Raven Press, 1986.
  5. ^ a b c d Tanaka, Y., Albert, M. L., Hara, H., Miyashita, T., & Kotani, N. (2000). Forced hyperphasia and environmental dependency syndrome. Journal of Neurology, Neurosurgery & Psychiatry, 68(2), 224-226. doi: http://dx.doi.org/10.1136/jnnp.68.2.224
  6. ^ Lhermitte, F., Pillon, B., & Serdaru, M. (1986)Human autonomy and the frontal lobes. Part I. Imitation and utilization behavior: A neuropsychological study of 75 patients. Annals of Neurology, 19, 326-334
  7. ^ (Ishihara, K., Nishino, H., Maki, T., Kawamura, M., & Murayama, S. (2002)Utilization behavior as a white matter disconnection syndrome. Cortex, 38(3), 379-387.
  8. ^ Lhermitte, F. (1983)Utilization behavior and its relation to lesions of the frontal lobes. Brain 106: 237–255.
  9. ^ Luria, A. R. (1980)Higher cortical functions in man. New York: Basic Books
  10. ^ Merriam Webster' Collegiate Dictionary. 10th ed. Springfield, Mass: Merriam Webster Inc;1996
  11. ^ Hoffmann, M. (2007). Transient environmental dependency syndrome due to phendimentrazine tartrate. European Neurology, 58(1), 49-50. doi: http://dx.doi.org/10.1159/000102167
  12. ^ van Vugt P, Paquier P, Kees L,et al. Increased writing activity in neurological conditions: a review and clinical study. F Neurol Neurosurg Psychiatry 1996;61:510–14.
  13. ^ Shimomura T, Ikeda M, Imamura T,et al. Forced language response of frontal dementia [abstract]. Japan Journal of Neuropsychology 1995;11:257. (In Japanese.)
  14. ^ Branzelli M, Colombo N, Della Sala S, Spinnler H. Spared and impaired cognitive abilities after bilateral frontal damage. Cortex 1994; 30: 27–52
  15. ^ Conchiglia, G., Della Rocca, G., & Grossi, D. (2007)On a peculiar environmental dependency syndrome in a case with frontal-temporal damage: Zelig-like syndrome. Neurocase, 13(1), 1-5. doi: http://dx.doi.org/10.1080/13554790601160558.
  16. ^ a b Paquier, C. R., & Assal, F. (2007). A case of oral spelling behavior: Another environmental dependency syndrome. Cognitive and Behavioral Neurology, 20(4), 235-237. doi: http://dx.doi.org/10.1097/WNN.0b013e31814da110
  17. ^ a b Lubinski R. Dementia and Communication. San Diego, London:Singular Publishing Group; 1997.
  18. ^ a b Mendez MF, Perryman KM, Ponton MO, et al. Bilingualism and dementia. J Neuropsychiatry Clin Neurosci. 1999;11:411–412