Dementia

Dementia is the general name for a decline in cognitive abilities that impacts a person's ability to do everyday activities. This typically involves problems with memory, thinking, and behavior. Aside from memory impairment and a disruption in thought patterns, the most common symptoms include emotional problems, difficulties with language, and decreased motivation. The symptoms may be described as occurring in a continuum over several stages. Dementia ultimately has a significant effect on the individual, caregivers, and on social relationships in general. A diagnosis of dementia requires the observation of a change from a person's usual mental functioning and a greater cognitive decline than what is caused by normal aging. Several diseases and injuries to the brain such as a stroke can give rise to dementia. However, the most common cause is Alzheimer's disease, a neurodegenerative disorder. The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), has re-described dementia as either a mild or major neurocognitive disorder with varying degrees of severity and many causative subtypes. The International Classification of Diseases (ICD-11) also classes dementia as a neurocognitive disorder (NCD) with many forms or subclasses. Dementia is listed as an acquired brain syndrome, marked by a decline in cognitive function, and is contrasted with neurodevelopmental disorders. Dementia is also described as a spectrum of disorders with causative subtypes of dementia based on a known disorder, such as Parkinson's disease, for Parkinson's disease dementia; Huntington's disease, for Huntington's disease dementia; vascular disease, for vascular dementia; HIV infection, causing HIV dementia; frontotemporal lobar degeneration for frontotemporal dementia; or Lewy body disease for dementia with Lewy bodies, and prion diseases. Subtypes of neurodegenerative dementias may also be based on the underlying pathology of misfolded proteins such as synucleinopathies, and tauopathies.