Behavioural and psychological symptoms of Alzheimer type dementia are not correlated with plasma homocysteine concentration.

Background/aims: Vitamin B12 and folate deficiencies have been associated with cognitive impairment and various psychiatric symptoms but not specifically with behavioural and psychological symptoms of dementia (BPSD). A limitation of previous studies in dementia was lack of concurrent homocysteine measurement especially as it may provide a better indicator of tissue activities of these vitamins. This study was designed to clarify whether a relationship exists between plasma homocysteine concentration and BPSD.

Methods: Plasma homocysteine, serum vitamin B12 and folate were measured in 23 Alzheimer's disease (AD) patients with BPSD and 27 AD patients without BPSD as determined through the use of the Neuropsychiatric Inventory (NPI). Blood levels of measured substances were also correlated with individual NPI scores and with cumulative NPI scores for different cluster of symptoms.

Results: There was no significant difference (p = 0.956) in the mean plasma homocysteine levels between AD patients with BPSD (17.48 micromol/l) and AD patients without BPSD (17.34 micromol/l). Similarly, there was no significant difference between the two groups in the mean serum B12 (382.61 and 391.60 pg/ml, respectively) and folate (7.95 and 10.02 ng/ml, respectively). Mean levels for both vitamins were well within the laboratory reference range. Neither individual nor cluster NPI scores correlated significantly with plasma homocysteine.

Conclusion: This study shows for the first time that BPSD are not associated with hyperhomocysteinaemia in Alzheimer dementia. Although previous studies have identified homocysteine as an independent risk factor in AD, the results reported here do not lend weight to an aetiological role for homocysteine specifically in BPSD.