The validity of the family history method for identifying Alzheimer disease
G. Li, M. Aryan, J. M. Silverman, V. Haroutunian, D. P. Perl, S. Birstein, M. Lantz, D. B. Marin, R. C. Mohs and K. L. Davis
Department of Psychiatry, University of Washington, Seattle, USA.
OBJECTIVE: To examine the validity of the family history method for
identifying Alzheimer disease (AD) by comparing family history and
neuropathological diagnoses. METHODS: Seventy-seven former residents of the
Jewish Home and Hospital for the Aged, New York, NY, with neuropathological
evaluations on record were blindly assessed for the presence of dementia
and, if present, the type of dementia through family informants by
telephone interviews. The Alzheimer's Disease Risk Questionnaire was used
to collect demographic information and screen for possible dementia. If
dementia was suspected, the Dementia Questionnaire was administered to
assess the course and type of dementia, i.e., primary progressive dementia
(PPD, likely AD), multiple infarct dementia, mixed dementia (i.e., PPD and
multiple infarct dementia), and other dementias based on the modified
Diagnostic and Statistical Manual of Mental Disorders, Third Edition,
criteria. RESULTS: Sixty (77.9%) of 77 elderly subjects were classified as
having dementia and 17 (22.1%) were without dementia by family history
evaluation. Of the 60 elderly subjects with dementia, 57 (95%) were found
at autopsy to have had neuropathological changes related to dementia. The
sensitivity of the family history diagnosis for dementia with related
neuropathological change was 0.84 (57 of 68) and the specificity was 0.67
(6 of 9). Using family history information to differentiate the type of
dementia, the sensitivity for definite or probable AD (with or without
another condition) was 0.69 (36 of 51) and the specificity was 0.73 (19 of
26). The majority (9 of 15) of patients testing false negative for PPD had
a history of stroke associated with onset of memory changes, excluding a
diagnosis of PPD. CONCLUSIONS: Identifying dementia, in general, and AD, in
particular, has an acceptable sensitivity and specificity. As is true for
direct clinical diagnosis, the major issue associated with misclassifying
AD in a family history assessment is the masking effects of a coexisting
non-AD dementia or dementia-related disorders, such as stroke. Including
mixed cases, ie, PPD and multiple infarct dementia in estimates of the
familial risk for AD can reduce the extent of underestimation of PPD.
