Observations on dementias with possibly reversible symptoms.

While the evaluation of patients with dementia must also address the possibility of treatable illnesses, recent studies found that reversible diseases are detected in only about 1% of dementia cases. Data on the frequency and evolution of potentially reversible dementias (PRD) in defined clinical settings can be useful in order to optimize diagnostic protocols, thus reducing over-investigation and waste of resources. We reviewed a series of 513 patients (mean age 69.3 +/- 4.2 years, mean education level 7.4 +/- 4.5 years, sex ratio M/F 217/296) referred to a memory clinic by their general practitioner, in order to identify PRD. All the subjects had undergone neurological and neuropsychological examination, and laboratory tests. Patients considered to be demented also underwent CT brain scan. 362 patients (70.6%) met the criteria for dementia. We identified 26 PRD cases (7.2% of dementia cases, 5.1% of the entire sample). In 13 patients (3.6% of dementia cases), a complete clinical and neuropsychological reversal of dementia was seen after treatment. In 5 of them (1.4%), a partial regression was obtained, while 8 showed no improvement. We conclude that potential and actual reversibility do not coincide, and that "true" reversibility is rare (even if not negligible) in clinical practice. Careful clinical history and examination appeared the most useful part of the evaluation to identify PRD. Standard blood tests and vitamin B12 assay were also useful, while CT scan detected PRD causes only in patients with evidence of neurological signs.