WASHINGTON - ELDERLY people with high blood pressure may be more likely to develop thinking and learning problems that can lead to dementia, researchers said on Monday.

Hypertension was linked to one of two types of mild cognitive impairment, a condition that can foreshadow the development of dementia, but not the type strongly associated with Alzheimer's disease, according to the study published in the journal Archives of Neurology.

People with mild cognitive impairment can have difficulties with language, memory, attention span or other mental functions significant enough to be noticeable to other people and to be detected in tests. One type significantly affects memory, and the other does not.

The impairment is not enough to interfere with daily life and the person does not show other symptoms of dementia.

The elderly people with high blood pressure in this study often had a form of mild cognitive impairment that can be a precursor to vascular dementia, the second most common form of dementia after Alzheimer's disease.

It is often associated with stroke. High blood pressure raises the risk for stroke.

'It looks like hypertension leads to a cognitive impairment which is actually not really memory impairment but impairment in other cognitive domains,' in particular, language and the ability to perform familiar tasks, Dr Christiane Reitz of Columbia University Medical Center in New York, one of the researchers said..

The researchers tracked 918 people in New York, average age 76, who did not have mild cognitive impairment when they entered the study from 1992 through 1994.

They were given physical exams and cognitive tests when they entered the study, and then were reexamined about every 18 months. They were followed for an average of 4-1/2 years, during which 334 of them developed mild cognitive impairment.

Those with high blood pressure had a 40 per cent increased risk of developing mild cognitive impairment, and, more significantly, a 70 per cent higher risk for the 'non-amnestic' form that does not involve broader memory difficulties.

'These findings suggest that prevention and treatment of hypertension may have an important impact in lowering the risk of cognitive impairment,' the researchers wrote.

Previous research has been inconclusive about a link between high blood pressure and either mild cognitive impairment or dementia, they added.

Another study focusing on the health consequences of high blood pressure appeared in the journal Archives of Internal Medicine. Those researchers tracked a nationally representative sample of 4,646 US adults.

About three-fourths of those who had conditions such as coronary heart disease, stroke, diabetes or others that raise the risk for cardiovascular complications also had high blood pressure, the study found. -- REUTERS