Early-onset Alzheimer's not always associated with memory loss

22 may 2011-- In a recent study published in the journal Neurology, scientists say that individuals who develop early-onset Alzheimer's in middle age are at a high risk of being misdiagnosed because many of their initial symptoms are not memory related.

Scientists, led by Dr. Albert Llado from the Hospital Clinic of Barcelona, examined the brain tissue from 40 patients who had suffered from early-onset Alzheimer’s disease. Of these 40 patients, 15 had not shown any of the typical signs of memory loss. The patients had displayed language disturbances, vision problems and behavioral changes. Out of these 15 patients, 53 percent had been misdiagnosed with neurological disorders and other forms of dementia, with 47 percent still having the incorrect diagnosis at their time of death. Of the patients that did show signs of memory loss, only four percent had been misdiagnosed at the beginning.

Early-onset Alzheimer’s usually hits patients between the ages of 40 and 60, and this study stresses the importance in recognizing that memory loss is not always an initial symptom. While there is currently no cure for Alzheimer’s, there is medication and behavioral treatment designed to delay the progression of the disease. In all 40 patients in the study, there was a delay of almost three years before a diagnosis was given, even in those with memory issues. The scientists believe this is because most physicians do not look for dementia and Alzheimer’s in patients in this age group.

The Alzheimer’s Association reports that 5.4 million Americans currently have Alzheimer’s and of this number 200,000 of them are between the ages of 40 - 65.

More information: Clinical features and APOE genotype of pathologically proven early-onset Alzheimer disease, Neurology May 17, 2011 vol. 76 no. 20 1720-1725. doi:10.1212/WNL.0b013e31821a44dd

Abstract

Objectives: Early-onset Alzheimer disease (EOAD) diagnosis often represents a challenge because of the high frequency of atypical presentations. Our aim was to describe the clinical features, APOE genotype, and its pathologic correlations of neuropathologic confirmed EOAD.

Methods: Retrospective review of clinical data (age at onset, family history, clinical presentation, diagnostic delay, diagnosis) and APOE genotype of patients with neuropathologically confirmed EOAD (<60 years).

Results: Forty cases were selected. Mean age at onset was 54.5 years (range 46–60). The mean disease duration was 11 years with a mean diagnostic delay of 3.1 years. A total of 37.5% had a nonmemory presentation. Behavioral/executive dysfunction was the most prevalent atypical presentation. Incorrect initial clinical diagnoses were common (53%) in patients with atypical presentations, but rare when anterograde amnesia was the presenting symptom (4%). The incorrect initial clinical diagnoses were 2 behavioral variant frontotemporal lobar degeneration, 2 normal pressure hydrocephalus, 1 semantic dementia, 1 primary progressive aphasia, 1 corticobasal degeneration, 1 pseudodementia with depression, and 1 unclassifiable dementia. APOE genotype was ϵ3/ϵ3 in 59%, with no significant differences between typical and atypical presentations. APOE ϵ4 was 3.3 times more frequent in subjects with family history of AD. A total of 97.5% of the cases presented advanced neurofibrillary pathology. A total of 45% of the patients had concomitant Lewy body pathology although localized in most cases and without a significant clinical correlate.

Conclusion: One third of patients with pathologic confirmed EOAD presented with atypical symptoms. Patients with EOAD with nonamnestic presentations often receive incorrect clinical diagnoses.