Do raised brain aluminium levels in Alzheimer's dementia contribute to cholinergic neuronal deficits?

Raised aluminium levels have been found in brains of patients with Alzheimer's dementia (1,2), a disease in which reductions have been reported in various parameters of presynaptic cholinergic nerve function, including choline uptake, acetylcholine synthesis and choline acetyltransferase activity (3). Aluminium has been found to inhibit choline transport by isolated rat brain nerve endings (4) and human erythrocytes (5), and also to cause an encephalopathy in rabbits with neurofibrillary tangles and reduced neuronal choline acetyltransferase activity (6). It is therefore hypothesised that raised brain aluminium levels in Alzheimer's dementia may contribute to the cholinergic neuronal deficits in this disease. If this is the case, then aluminium chelating agents may be of value in its treatment.