‘Dementia’ is an umbrella term for a number of progressive, organic brain diseases that affect approximately 850,000 people in the UK. Most neurodegenerative diseases leading to dementia are characterized by processes that result in the aberrant polymerization of proteins. A small proportion of individuals with these diseases develop dementia as a direct result of mutations or polymorphisms in genes influencing these processes. The most common cause of dementia is Alzheimer's disease. Other important causes include vascular dementia, dementia with Lewy bodies and fronto-temporal dementia. The management of dementia largely focuses on helping patients and families to cope with increasing care needs as the disease progresses, and with the emergence of troublesome neuropsychiatric symptoms. Current pharmacological treatments are based on the neurochemical changes that are found in these diseases. Cholinesterase inhibitors and N-methyl-d-aspartate receptor antagonists offer some help in ameliorating the inevitable cognitive decline found in Alzheimer's disease. However, the treatment of neuropsychiatric symptoms in dementia is still largely empirical and is hampered by either limited efficacy or troublesome adverse effects.