Purpose: White matter hyperintensities (WMHs) on magnetic resonance imaging (MRI) are commonly found in Alzheimer's disease (AD) and may contribute to cognitive impairment. Plasma total homocysteine (tHcy) had also been linked with cognitive decline in AD. We examined the relationship among change of cognition, tHcy level, and WMHs on MRI in AD patients with a follow-up periods of 6 months.
Methods: AD patients with normal creatinine level and initial clinical dementia rating (CDR) of 1 to 2 were enrolled. tHcy and biochemistry tests related to cerebral vascular risk factors were collected. WMHs were measured on MRI fluid attenuated inverse recovery sequence and classified into deep white matter hyperintensities (DWMHs) and periventricular white matter hyperintensities (PWMHs) by visual rating scale. Neuropsychological tests including cognitive ability screening instrument (CASI), mini-mental state examination (MMSE) converted from CASI scores and CDR were collected twice during the follow- up period of 6 months.
Results: Ninety-two AD patients, 30 men and 62 women completed the study while the tHcy level was not significantly different between AD and age matched controls. tHcy level showed no correlation with CASI or MMSE score, at either the first or second examination. tHcy showed positive correlation with decline of CASI total score and abstract thinking (both p<0.01) but not in MMSE decline. There was no significant correlation between neuropsychiatric assessment and WMHs, but the decline of abstract thinking score was related to frontal PWMHs (R square=0.237, p=0.007).
Conclusion: tHcy might be associated with rapid cognitive decline in AD after a 6-month follow-up period and the effect might not be directly through WMHs. tHcy level correlated with greater WMHs in the trigone area although greater lesion load by MRI was in the occipital lobe.