Dementia (from Latin demens) is progressive decline in cognitive function due to damage or disease in the brain beyond what might be expected from normal aging. Particularly affected areas may be memory, attention, language and problem solving, although particularly in the later stages of the condition, affected persons may be disoriented in time (not knowing what day, week, month or year it is), place (not knowing where they are) and person (not knowing who they are). Dementia can be classified as either reversible or irreversible depending upon the etiology of the disease. Dementia is a non-specific term that encompasses many disease processes just as fever is attributable to many etiologies.

Affected persons may also show signs of psychosis, depression and delirium. Early symptoms consisting of personality changes, to change in behavior. Often dementia can be first evident during a episode of delirium. There is a higher prevalance of eventually developing dementia in individuals who experience an acute episode of confusion while hospitilized.

Dementia can effect language, comprehesion, motor skills, short term memory, ability to identify commonly used items, reaction time, personality traits, and executive functioning.

Diagnosis

Proper differential diagnosis between the types of dementia (see below) will require, at the least, referral to a specialist, e.g. a geriatrician or neurologist. However, to establish dementia as a possibility the abbreviated mental test score and the mini mental state examination are used.

An AMTS score of less than six and an MMSE score under 24 suggests dementia. Routine blood tests should be performed to rule out treatable causes. These tests include vitamin B12, folic acid, thyroid-stimulating hormone (TSH), C-reactive protein, full blood count, electrolytes, calcium, renal function and liver enzymes. Abnormalities may suggest vitamin deficiency, infection or other problems that commonly cause confusion or disorientation in the elderly. Chronic use of substances such as alcohol can also predispose the patient to cognitive changes suggestive of dementia.

A CT scan is commonly performed. This may reveal normal pressure hydrocephalus, a reversible cause of dementia, and can confirm other types of dementia (ischemic changes in vascular dementia and atrophy in Alzheimer's).

The final diagnosis of dementia is made on the basis of neuropsychological testing for various cerebral functions. This rules out frequent comorbidity, such as depression, and has the benefit of identifying areas in which the patient will need more help to function properly.

Types

The most common types of dementia are as follows and vary according to the history and the presentation of the disease:

• Alzheimer's disease
• Multi-infarct dementia (also known as vascular dementia), including Binswanger's disease
• Dementia with Lewy bodies (DLB)
• Pick's disease (or frontotemporal lobar degeneration/FTLD)
  • Frontal variant frontotemporal dementia
  • Semantic dementia
  • Progressive non-fluent aphasia

Approximately 10% of a sample of suspected dementia cases have a potentially treatable cause. These include:

• Depressive pseudodementia
• Acute confusional state or delirium
• Hypothyroidism
• Normal pressure hydrocephalus
• Vitamin B12 deficiency
• Vitamin B6 (thiamin) deficiency
• Tumour
• Or, in very rare cases:
  • Head trauma
  • Parkinson's disease
  • Huntington's disease
  • Down's syndrome
  • Creutzfeldt-Jakob disease
  • AIDS

External links

• Dementia tutorial for U.K. practitioners by the Alzheimer's Society