Good care for patients suffering from serious cognitive impairment can be even more expensive and difficult to find than ordinary long term care, according to results of a new survey.

Only half of U.S. nursing homes have separate care units for dementia patients, and only 61% of assisted living facilities provide care for people suffering from Alzheimer’s disease and other forms of dementia, according to a report on the survey, which was sponsored by the MetLife Mature Market Institute, Westport, Conn.

Nursing homes charge $10 to $25 extra per day for patients in the dementia units, researchers say.

About half of the assisted living facilities that provide dementia care charge extra fees for that service, with the costs ranging from $50 to $3,000 per month, researchers say.