Subcortical hyperintensities in Alzheimer's disease: no clear relationship with executive function and frontal perfusion on SPECT.

Background/aims: To investigate relationships between subcortical hyperintensities (SH), frontal perfusion and executive function (EF) in a sample of Alzheimer's disease (AD) patients with varying severities of SH.

Methods: A sample of 63 AD patients underwent brain imaging with magnetic resonance imaging (MRI) and single photon emission computed tomography (SPECT) scans. Severity of SH was assessed using a standardized visual rating scale on MRI. Patients were classified into severe (n=20), moderate (n=23) or no SH (n=20) groups. Four frontal SPECT regions of interest (anterior cingulate cortex, dorsolateral prefrontal cortex) and neuropsychological assessment of EF were analyzed.

Results: Overall, no significant relationships were found between severity of SH and measures of SPECT perfusion or EF, except for one subsection of the Dementia Rating Scale, with severe SH scoring slightly worse than the other two groups.

Conclusion: These findings support previous studies which suggest minimal adverse effects of SH on brain function and cognition. Global severity of SH on MRI in AD was not associated with decline in frontal perfusion and only mildly related to a decline in a specific EF task. More accurate measures of SH volume, not just global severity of SH, may be necessary to capture such complex brain behavior relationships; if they do indeed exist.