PREVALENCE OF POTENTIALLY REVERSIBLE DEMENTIAS AND ACTUAL REVERSIBILITY IN A MEMORY CLINIC COHORT

Background: Although clinics for the evaluation of cognitive dysfuncti on have typically emphasized the detection and treatment of the revers ible causes of dementia, it remains unclear whether the treatment of s uch causes results in reversal of the dementia. Therefore, the appropr iate work-up for dementia is in dispute. Methods: A chart review was p erformed with records from an urban tertiary care referral-based memor y clinic. The records for 196 patients with dementia or suspected deme ntia, seen between October 1991 and December 1993, were examined to de termine the prevalence of potentially reversible dementias and whether the cognitive dysfunction improved or resolved after treatment. Data abstracted from the medical charts included demographic information, m edication use, presence of depression, and results of neuropsychologic al tests, blood work and neuroimaging. The clinical diagnosis, the res ponse to treatment, if applicable, and the outcome (mean follow-up per iod 16 months) were analysed. The recommendations of the 1989 Canadian Consensus Conference on the Assessment of Dementia (CCCAD) on the use of CT were retrospectively applied in each case. Results: Of the 196 patients, 45 (23.0%) had a potentially reversible condition identified by history, physical examination, blood testing or CT; in only 7 (3.6 % of the total) did treatment result in improvement or resolution of t he dementia. These 7 patients had higher results for the Mini-Mental S tate examination (mean result 26) and exhibited only mild cognitive de ficits. Potentially reversible lesions were found in the CT scans of 6 (3.1%) patients: 4 had normal-pressure hydrocephalus and 2 had a brai n tumour. If the CCCAD recommendations had been followed, CT would hav e been performed in 76 (38.8%) of the patients, and 1 of the 6 patient s with a lesion would have been missed. Interpretation: Both potential and actual reversibility of dementia was low in these memory clinic p atients. The patients whose condition improved with intervention had e arly and milder cognitive deficits, which suggests that thorough evalu ation of early memory loss is warranted.