The cholinergic hypothesis of Alzheimer’s disease: a review of progress
- aDementia Research Laboratory, Neuroscience Research Centre, Guy’s, King’s and St Thomas’ Schools of Biomedical Sciences, King’s College, London, SE1 9RT, UK, bCerebrus, Oakdene Court, 613 Reading Road, Winnersh, Wokingham, RG41 5UA, UK, cDepartment of Care of the Elderly, Frenchay Hospital, Bristol, BS16 2EW, UK
- Dr Paul T Francis, Dementia Research Laboratory, Division of Biomolecular Sciences, Guy’s, King’s and St Thomas’ Schools of Biomedical Sciences, King’s College, St Thomas Street, London SE1 9RT, UK. Telephone 0044 171 955 2611; fax and answer phone 0044 171 955 2600; email p.francis{at}umds.ac.uk
- Received 11 June 1998
- Revised 20 October 1998
- Accepted 30 October 1998
Abstract
Alzheimer’s disease is one of the most common causes of mental deterioration in elderly people, accounting for around 50%-60% of the overall cases of dementia among persons over 65 years of age. The past two decades have witnessed a considerable research effort directed towards discovering the cause of Alzheimer’s disease with the ultimate hope of developing safe and effective pharmacological treatments. This article examines the existing scientific applicability of the original cholinergic hypothesis of Alzheimer’s disease by describing the biochemical and histopathological changes of neurotransmitter markers that occur in the brains of patients with Alzheimer’s disease both at postmortem and neurosurgical cerebral biopsy and the behavioural consequences of cholinomimetic drugs and cholinergic lesions. Such studies have resulted in the discovery of an association between a decline in learning and memory, and a deficit in excitatory amino acid (EAA) neurotransmission, together with important roles for the cholinergic system in attentional processing and as a modulator of EAA neurotransmission. Accordingly, although there is presently no “cure” for Alzheimer’s disease, a large number of potential therapeutic interventions have emerged that are designed to correct loss of presynaptic cholinergic function. A few of these compounds have confirmed efficacy in delaying the deterioration of symptoms of Alzheimer’s disease, a valuable treatment target considering the progressive nature of the disease. Indeed, three compounds have received European approval for the treatment of the cognitive symptoms of Alzheimer’s disease, first tacrine and more recently, donepezil and rivastigmine, all of which are cholinesterase inhibitors.
