Introduction compromised in AD [2] and the resultant cholinergic deficit contributes to the cognitive impairment of these Alzheimer’s Disease (AD) is the most common single cause of dementia in our ageing society. Traditionally patients [3]. Although many believe this ‘cholinergic hypothesis’ to be important, others feel it represents a less thought of as an untreatable degenerative condition, recent advances in drug therapy have challenged this view. significant component of the disease process [4]. Many other neurotransmitters are affected in AD, and the The disease is characterised by an insidious decline in cognitive and non-cognitive function. Classically, short relative importance of each in relation to clinical findings has not been fully elucidated. and long-term memory is impaired while language skills, concentration and attention are often affected. Thisresults Initial work focused on the use of acetylcholine precursors, using a similar rationale to dopamine therapy in impaired ability to learn and retain new skills as well as the loss of existing ones. Non-cognitive function is in Parkinson’s disease. A series of small trials using precursors such as choline and phosphatidylcholine the global term used to describe problems such as depression, agitation, personality changes, delusions and showed no reliable improvement in cognitive function, with only 10 out of 43 trials reporting any positive effect hallucinations. These factors have a significant impact on patient behaviour and a very real impact on the quality[5]. There has been renewed interest in muscarinic agonists drugs, which when first introduced, had major of life for both patients and caregivers. Diagnosis of AD is clinically based, and using the NINCDS-ADRDA problems with adverse cholinergic effects. Better understanding of the molecular pathology of muscarinic criteria (Table1)[1], a diagnosis of probable or possible AD can be made. Definitive diagnosis relies on pathologi- receptors and their subtypes has led to the development of more specific agonists. Drugs such as xanomeline, cal confirmation, which in the majority of cases is rarely completed. With the development of AD specific milameline, and civimeline have reached clinical trials, and the improvements seen in cognitive function are treatments, definition of AD from other types of dementia is very important. reviewed by Avery et al.[6]. There are also claims that these drugs have disease modifying properties, with effects on APP processing and tau phosphorylation. Muscarinic