Lack of prognostic significance of SPECT abnormalities in non-demented elderly subjects with memory loss

Objective: To determine if hypoperfusion abnormalities on single photon emi ssion computed tomography (SPECT) are associated with poorer cognitive func tion at baseline or increased risk of decline in cognitive function and pro gression to dementia in memory-impaired but non-demented elderly subjects m eeting the criteria for aging associated cognitive decline (AACD). Design: Cross sectional study of 36 AACD subjects comparing hexamethyl propylene-am ine oxime (HMPAO) SPECT results rated by visual inspection with base line c ognitive functioning. Prospective study of these AACD subjects with clinica l and neuropsychological follow-up over 35 months. Setting: The memory clin ic and nuclear medicine unit of a university teaching hospital. Subjects: T hirty-six subjects meeting the criteria for AACD recruited from patients se en on a physician referral basis. Main outcome measures: 1) Baseline cognit ive function as measured by the Mini Mental State Examination (MMSE), Bosto n naming, Logical Memory I subtest of the WAIS-R, and verbal fluency, corre lated with SPECT status. 2) Decline in cognitive function as measured by cl inical exam and the MMSE, with progression to dementia on follow-up being c orrelated with SPECT status at baseline. Results: 18 of the 36 subjects pro gressed to dementia (probable Alzheimer's Disease) over follow-up. No corre lation was found between the presence or absence of SPECT abnormality and M MSE or other cognitive measures. There was no correlation between the prese nce or absence of SPECT abnormality at initial examination, and cognitive d ecline according to the MMSE, or with the occurrence of clinical dementia o n follow-up. Conclusions: We conclude that SPECT abnormalities assessed by visual inspection do not correlate with severity of impairment in AACD indi viduals, and are not useful in predicting progression to dementia in AACD s ubjects.