Dementia with Lewy bodies (DLB) is caused by the development of tiny protein deposits called 'Lewy bodies' inside nerve cells in areas of the brain that control aspects of memory and motor function. These disrupt brain activity by reducing levels of chemical messengers and causing cell death. DLB accounts for around one in 25 cases of dementia and is more common in men than women.

In the early stages, patients often show similar symptoms to Parkinson's disease, with tremors (particularly in the hands), stiffness, shuffling gait, blank facial expression and reduced mobility. Other symptoms may include:

• Visual hallucinations €“ a very common symptom (auditory hallucinations are less common). These can be distressing for both the patient and their family or carers
• Difficulty judging distances and identifying 3D objects
• Problems with planning and organising
• Depression
• Memory problems (less common in the early stages of DLB than in AD)
• Falls due to motor symptoms and imbalance
• Sleep disorders, which can be distressing and physically harmful for their sleeping partner.