Dear Dr. Gott: I applaud your approach to Alzheimer's disease and other cognitive impairments. Blood work and imaging studies are important in making or ruling out certain diagnoses.

I take strong exception, however, to your statement that there is no specific testing for Alzheimer's disease.

The field of clinical neuropsychology is a subspecialty within clinical psychology. It has existed as a clinical discipline since about the late 1970s.

Neuropsychologists use detailed standardised testing of a range of brain functions (e.g. memory, attention, perception, executive abilities, language, personality, etc.).

Decades of careful research now allow neuropsychologists to recognise the hallmark early features of a range of neurological disorders that affect cognition, and to assist with the diagnosis of these conditions. As a clinical neuropsychologist, it is often part of my job to differentiate between normal changes in memory that occur with ageing, isolated memory problems (that do not constitute dementia) and a range of patterns that are associated with the different dementias. For example, in the early to middle stages, it is possible to differentiate between a subcortical presentation (as you would see in Parkinson's disease) and presentations that are more cortical (like Alzheimer's disease).

Another common clinical presentation is frontotemporal dementia, with its classic features that are different than Alzheimer's.

Vascular dementia has other patterns. Neuropsychologists also commonly differentiate between depression and dementia.

Alzheimer's disease, in particular, has been heavily studied for decades. Although it is not a perfect science, we can detect early Alzheimer's classic features, and there are even markers for pre-Alzheimer's presentations that are under study, allowing us to predict who will go on to develop it.

My goal is to highlight to you the contributions of neuropsychology as an important diagnostic tool in dementia evaluations.

All patients who are suspected of having memory problems or other cognitive changes should be seen for neuropsychological testing.

Reply: I was unaware (as I am sure many other doctors are, as well) of your field and the apparent advancements it has made with respect to the early diagnosis of various dementias.

I have printed your letter in the hopes it will bring awareness of your speciality.

Both physicians and patients could benefit from being able to refer patients for early diagnosis, or to rule out a diagnosis. Thank you for informing me of your speciality.

For readers who would like more information, I recommend ordering my "Alzheimer's Disease" Health Report. It is available by sending a self-addressed, stamped number 10 envelope and $2 to Newsletter, PO Box 167, Wickliffe, Ohio 44092. Be sure to mention the title.

Doctor Gott is a retired physician and the author of "Dr. Gott's No Flour, No Sugar Diet" and "Dr. Gott's No Flour, No Sugar Cookbook". Contact him c/o United Media, 200 Madison Avenue, fourth floor, New York, New York 10016.