Rate of memory decline differs by dementia type

By Scott Baltic

NEW YORK , 12 feb 2009– The rate at which people with dementia lose their memory differs significantly according to the type of dementia they have, new research from France suggests. The research also highlights the importance of early health care in elderly people who develop dementia.

After Alzheimer's disease (AD) alone, AD with cerebrovascular disease and vascular dementia are the leading causes of dementia. Vascular dementia is often associated with stroke. High blood pressure and smoking are risk factors.

Little is known about the progression of either AD with cerebrovascular disease or vascular dementia, Dr. Florence Pasquier of Hopital Salengro in Lille and colleagues note.

To investigate, they followed for an average of 4.7 years 970 patients diagnosed at a memory clinic between 1995 and 2001 -- 663 were diagnosed with AD alone, 166 with AD plus cerebrovascular disease and 141 with vascular dementia. The average age of study subjects was 73 years.

The researchers assessed cognitive function every 6 to 12 months during follow up using the Mini Mental State Examination

(MMSE).

Results showed that patients with AD plus cerebrovascular disease were older than patients with the other two types of dementia, both at onset and at first study visit.

The starting MMSE score was highest -- indicating better cognitive function -- for patients with vascular dementia compared with those with AD plus cerebrovascular disease and AD alone.

It is noteworthy, according to Pasquier and colleagues, that the average annual decline in cognitive function was significantly different for the three types of dementia.

The decline was greatest for patients with AD alone, followed by those with AD plus cerebrovascular disease and those with vascular dementia.

Although mortality was not significantly affected by dementia type, the older that patients were at the time of clinical assessment, the sooner they died, independently of diagnosis and starting cognitive function.

Also, regardless of diagnosis, the shorter the time between the onset of symptoms and the first visit to the memory clinic, the longer the patients survived. This finding, the researchers say, highlights the beneficial role of early healthcare in people who show signs of memory trouble.

SOURCE: Journal of Neurology, Neurosurgery, and Psychiatry, February 2009.