Plasma and platelet clusterin ratio is altered in Alzheimer's disease patients with distinct neuropsychiatric symptoms: findings from a pilot study.

BACKGROUND: Clusterin protein in plasma has been found to differentiate between people with and without cognitive changes. However, these findings are not conclusive, despite the clusterin gene variations repeatedly being linked to increased risk for dementia, in particular Alzheimer's disease (AD). METHOD: We analysed the level of clusterin in platelet and plasma in 25 subjects with a clinical diagnosis of AD and 26 subjects with no cognitive impairment. RESULTS: In the current study, we report that the levels of both plasma and platelet clusterin are similar between AD and cognitively intact individuals. Clusterin plasma and platelet levels, as well as the plasma/platelet clusterin ratio, were not affected by age, gender, cognitive impairment and/or overt behavioural symptomatology, including presence of hallucinations and delusions, as well as depression. However, the plasma/platelet clusterin ratio was positively associated in with the Neuropsychiatric Inventory measures of agitation, apathy, irritability and motor aberrant behaviour in AD subjects. CONCLUSION: Previous inconsistencies in reported blood clusterin levels may be a result of underlying non-cognitive symptoms in people with AD. Our findings need now to be replicated in larger group of dementia subjects.