SERUM TUMOR-NECROSIS-FACTOR (TNF) IN ALZHEIMERS-DISEASE AND MULTIINFARCT DEMENTIA

Changes in neuroimmune parameters and cytokine production have been re ported in patients with Alzheimer's disease, including increased level s of interleukin-1 (IL-1) and histamine in brain tissue, cerebrospinal fluid and serum. Specific neuroimmune reactions may be responsible in part for astrogliosis and neuronal death in particular circumstances. Since IL-1 and tumor necrosis factor (TNF) tend to act synergisticall y in physiological conditions and in some pathological processes, we h ave studied the concentration of TNF-alpha in patients with Alzheimer' s disease (AD) or multi-infarct dementia (MID) and in age-matched cont rol subjects (CS) in order to evaluate possible changes in the levels of this cytokine with potential influence on the pathogenesis of AD. S erum TNF-alpha levels were significantly lower in AD (2.5 +/- 1.25 pg/ ml, p < 0.01) and MID (1.64 +/- 1.17 pg/ml, p < 0.001) than in CS (10. 66 +/- 8.92 pg/ml). A negative correlation between serum TNF-alpha lev els and age in AD was found (r = -0.645, p < 0.01); however no signifi cant correlations were detected between serum TNF-alpha levels and men tal performance, cerebrovascular risk heart rate and blood pressure in either AD or MID. In conclusion, there is a marked reduction in the c oncentration of serum TNF-alpha in both AD and MID which seems to be p oorly related to cognitive dysfunction and/or neurovascular damage, pr obably reflecting an endogenous immune dysregulation and/or an inhibit ory reactive process in demented patients.