The role of routine laboratory studies and neuroimaging in the diagnosis of dementia: A clinicopathological study

OBJECTIVE: To determine the neuropathological diagnoses of longitudinally f ollowed patients with potentially reversible causes of dementia and to exam ine the results of the "dementia work-up," especially neuroimaging, by comp arison with the pathological diagnosis. DESIGN: A neuropathologic series of 61 consecutive patients, with review of clinical, laboratory, neuroimaging, and pathological results. RESULTS: Of the 61 patients, forty-eight (79%) had a clinical diagnosis of probable or possible Alzheimer's disease (AD). Compared with the pathologic al diagnosis, the sensitivity and specificity of the clinical diagnosis of AD were 96% and 79%, respectively. Of the 61 patients, 9 had abnormal labor atory tests, the correction of which did not improve:the subsequent course. These patients were found to have AD(8) and frontotemporal demential on pa thology. In two patients, neuroimaging was helpful in the clinical diagnose s of frontotemporal dementia and progressive supranuclear palsy (PSP). Neur oimaging revealed cerebrovascular disease in 18 patients, only two of whom were suspected clinically. Pathology confirmed AD in 17 and PSP in 1 of the se patients. Sensitivity and specificity for the clinical diagnosis of cere brovascular disease in comparison with. pathology were 6% and 98%, respecti vely. With the added information from neuroimaging, Chat sensitivity increa sed to 59% and specificity decreased to 81%. CONCLUSIONS: All cases with abnormal laboratory or neuroimaging results had AD or some other neurodegenerative disease on pathology. The "dementia wor k-up" did not reveal any reversible causes for dementia in this group of pa tients. Neuroimaging may have a role, especially in the diagnosis of possib le AD with concomitant cerebrovascular disease.