PO Box 39081 Point Grey, Vancouver, BC Canada V6R 4P1
Phone/Fax 604-521-5535


This is the website for obtaining forms to order the

Behavioral Diagnostic Guide for Developmental Disabilities
© 1998 A. Gedye

- and the -

Gedye Dementia Scale for Down Syndrome
© 1995 A. Gedye

- et -

Échelle d'évaluation de la démence pour le Syndrome de Down
© 2000 A. Gedye (version française)

-- This site was last updated February 2015 --.

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Q        Does the acronym G-DSDS refer to the same test as the DSDS?
A        Yes. In 2015 the author's surname was added to the test's title to clearly indicate the developer of this dementia scale. The scale's acronym was therefore modified to G-DSDS from the former DSDS.

      Are there restrictions on who can purchase and use the GEDYE DEMENTIA SCALE FOR DOWN SYNDROME (G-DSDS)?

A        Yes. Only psychologists and psychometrists are permitted to use this psychological assessment tool. Only psychologists/psychometrists with university training in standardized testing and with experience in administering intelligence tests are qualified to purchase and use the G-DSDS. It is a very serious clinical decision to diagnose someone with dementia. It is additionally important to look for differential diagnoses when cognitive impairment presents and to consider possible reversible causes for cognitive decline. Although some physicians, psychiatrists, and nurses are experienced in the area of dementia, their training does not include using standardized instruments for assessing intelligence. The assessment of intelligence -- or a decline in intelligence -- is especially crucial when working with adults who were already below average intellectually before the onset of cognitive decline.

      I'm a psychiatrist in the field of Developmental Disabilities, and I want to purchase the G-DSDS.  Is that OK?
      Sorry, no. See the answer to the previous question.

Q        Are there any restrictions on who can purchase the Behavioural Diagnostic Guide ?
      No. In fact, it has been very useful to those not permitted to buy the G-DSDS

      Can I pay using a VISA or Mastercard credit card ?
      Sorry, no credit cards accepted, only checks, money orders, and bank drafts.

      Can I pay by wiring money to your bank account ?
      No. Please send a money order, bank draft or check for payment.

      What happens if I send in an order for the G-DSDS without signing or submitting the Purchaser Qualification Form (PQForm)?
      The order will not be processed until the psychologist/psychometrist who will be using the G-DSDS agrees to the conditions for use by signing and faxing/mailing in the PQForm.

      Do bookstores sell the G-DSDS or the Behavioral Diagnostic Guide for DD ?
A        The G-DSDS is not sold to Bookstores but only to psychologists and psychometrists. Bookstores can order the Behavioral Diagnostic Guide for DD, but it is just as easy for you to order it yourself directly from the author.  The price is unlikely to be less by going through a bookstore.

      I've found another Canadian site that sells the G-DSDS to psychologists. Why it is more expensive ?
A        That distributor first pays the same price as do psychologists who buy the G-DSDS Booklets and Manual directly from the author. Then that distributor adds its own costs to the price they charge.

Q        Is the G-DSDS for sale to psychologists in other languages ?
A        Yes, the G-DSDS/DSDS Manual and Test Booklet in FRENCH are available for psychologists using forms from this website.  The G-DSDS Test Booklet in SWEDISH is also available for psychologists. There is a dementia scale in Dutch by epidemiologist Dr. Marian Maaskant and educational specialist Dr. Joop Hoekman that uses the test items and differential diagnostic questions from Gedye’s Dementia Scale for Down Syndrome ©  A. Gedye 1995 by prior agreement.  However, that Dutch scale has many significant clinical differences from Dr. Gedye's scale and none of those changes was ever approved by Dr. Gedye. The Dutch scale is not a translation of the G-DSDS/DSDS and is NOT a substitute for the Dr. Gedye’s dementia scale.  (The title of the Dutch scale is:  "Dementieschaal voor mensen met een verstandelijke handicap".)

Q        When did the prices last change for the Dementia Scale and Behavioral Diagnostic Guide for DD ?
      The prices of the clinical book and test materials were reduced May 2012.

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