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Understanding Dementia & Praxis - DementiaGuide.com
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Understanding Dementia


This is an excerpt from the book Understanding Dementia, which is meant to be a practical manual for primary care physicians and other health care professionals. Chapter5 deals with the type of memory impairment that is involvied,which includes a description of praxis.

Apraxia is defined as the inability to carry out a previously learned motor activity, despite normal function of all the component parts (muscles, nerves, joints, etc.). Symptoms mentioned during the history, such as difficulties dressing or using a knife and fork, are often clues that apraxia is present. Testing for the presence of apraxia can be addressed throughout the visit, where problems such as using a pencil, undressing and dressing will be apparent. Other simple procedures include having the patient pantomime common activities such as combing their hair ("pretend you have a comb in your hand and comb your hair") and slicing bread ("show me, with both hands, how you would use a knife to cut a slice off a loaf of bread"). The abnormal response is to use the body part as the object, using a finger as the knife, or hand as the comb, gestures sometimes referred to as 'body-as-part apraxia.' Patients can also be asked to mimic meaningless gestures (ask the patient to do what you do, and then touch the desk with the edge of your hand, then the palm, then your fist) and spontaneously perform common gestures, such as waving. To have apraxia the muscles and nerves must function normally, and coordination and proprioception should be unimpaired. These features can be confirmed during the physical examination.

Visuospatial function
Visuospatial function contains, to some extent, elements of praxis, orientation, parts of memory, planning and concentration. Abnormalities in visuospatial function can be suspected from the history if the patient has become lost while driving, while walking in the neighbourhood, or within their home. In addition to the copying task in the MMSE, two quick tests of visuospatial function are clock drawing and house drawing. We ask the patient to draw a circle, fill in the numbers as if it were a clock, and then place the hands at a specified time (we ask for 10 minutes after 11). Abnormalities are obvious, and changes in clock drawing over time can be used to follow the course of the disease (see Figure 5.1). The patient can also be asked to draw (or copy) a house in perspective. We ask for a house with a front, a side, a roof, a door, windows and a chimney. Both the overall planning of the house and the level of detail are important to consider (see Figure 5.2). In somewhat more detailed testing, an inability to spontaneously draw a clock or a house that is corrected by cuing (i.e. by providing a clock or a house to copy) can point to frontotemporal dementia .

Rockwood & MacKnight, 2001. p. 80

Rockwood & MacKnight, 2001. p.81


Taken from Understanding Dementia: A Primer of Diagnosis and Management
Kenneth Rockwood & Chris MacKnight, 2001
Chapter 5, pp 78-81


See Also:
About Dementia > Alzheimer's Disease > Apraxia
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Last updated December 7, 2018
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