Homocysteine and cognitive impairment. Relation with diagnosis and neuropsychological performance.

Objective: Elevated total plasma homocysteine (tHcy) is a risk factor for cardiovascular and cerebrovascular disease, and it has also been proposed as an independent risk factor for dementia and Alzheimer's disease (AD). Its relationship with cognitive impairment, however, remains unclear. We aimed to determine the relationship of tHcy levels with clinical diagnoses and cognitive performance in a sample of outpatients with cognitive impairment.

Methods: Plasma tHcy, folate, vitamin B12 and creatinine levels were assessed in individuals evaluated at the Memory Disorder Unit. Diagnoses included subjective memory complaints (SMC, n = 27), mild cognitive impairment (MCI, n = 142), AD (n = 139) and vascular dementia (VD, n = 17). All patients underwent extensive neuropsychological testing to evaluate attention, memory, language, and visuoconstructional and executive functions, as well as depression and impairments of daily living activities.

Results: tHcy levels did not differ between patients with SMC, MCI, AD or VD. Increased tHcy was associated with worse performance in geometric figure copy and clock drawing tests.

Conclusions: tHcy levels did not discriminate between diagnostic groups of patients with cognitive impairments. Elevated tHcy levels in these patients appear to have a detrimental effect on visuoconstructional performance.