Alzheimer's delusions linked to dense brain tangles

NEW YORK, Dec 18 (Reuters Health) - A type of microscopic brain lesion that is a hallmark of Alzheimer's disease appears to be more dense in people with the illness who develop hallucinations and delusions, researchers report.

About half of all Alzheimer's disease patients develop such symptoms--known as psychosis--in addition to memory loss, depression and personality changes more commonly associated with the disease.

In a new study of 109 Alzheimer's disease patients, 63% were found to have hallucinations, delusions and other symptoms of psychosis. Based on autopsies, the researchers found that formations called neurofibrillary tangles in one region of the brain were 2.3 times as dense in patients with psychotic symptoms compared with those without such symptoms.

These differences were "particularly notable" in patients with mild Alzheimer's disease, Dr. Nuri B. Farber from Washington University in St. Louis, Missouri, and colleagues report in the December issue of the journal Archives of General Psychiatry.

The investigators also found that tangles tended to be denser in patients with more severe dementia, but they did not detect any significant relationship between dementia severity and psychotic symptoms.

Farber's team reports that there was no relationship between psychotic symptoms and tangles found in other parts of the brain and deposits called plaques, which have also been linked to Alzheimer's disease.

"Psychosis occurs very frequently" in patients with Alzheimer's disease, Farber told Reuters Health in an interview. But, Farber added, "We don't want people to come away with the idea that the tangles make you psychotic." He noted that tangles have not been found in the brains of people with other diseases that cause psychosis, such as schizophrenia.