Dementia has been defined as €a syndrome consisting of progressive impairment in two or more areas of cognition, sufficient to interfere with work, social function or relationships€.

In 2015, there were an estimated 856,700 people with dementia in the UK. Prevalence rates link the risk of dementia with increasing age, rising from one in 688 people under 65 years, to one in 14 people over 65 years, one in six over 80 years and one in three over 90 years.

Recent research suggests the proportion of people living with dementia has decreased by 20 per cent over the past two decades, linked mainly to a reduction in male smoking, leading healthier lives and a reduction of cardiovascular risks.

General symptoms

Dementia is gradual in onset, often noticed at times of stress or change. Early symptoms include:

• Memory loss, especially for recent events
• Difficulties with learning and/or retaining new information 
• Being more repetitive or misplacing objects such as car keys or spectacles
• Having trouble with complex tasks such as cooking, driving or dealing with finances
• Reduced ability to reason and problem-solve
• Impairment of spatial and visuospatial awareness, including bumping into objects, getting lost in a familiar place
• Language problems, including an inability to find the right word or difficulty following conversations
• Behavioural changes, including being more irritable, passive, withdrawn or suspicious.

There is no definitive marker for dementia. Diagnostic assessments include laboratory screening of blood indices and imaging techniques such as computed tomography (CT) scans to exclude space occupying lesions, and magnetic resonance imaging (MRI) and positron emission (PET) scanning to establish where brain loss is occurring and its severity. 

Psychological scales assess disease severity, cognitive functioning, activities of daily living, and problem solving.