Dementia differentiating dementia from other diseases

Dementia

• Delirium is distinguished from dementia (chronic organic brain syndrome) which describes an "acquired" (non-congenital) and usually irreversible cognitive and psychosocial decline in function. Dementia usually results from an identifiable degenerative brain disease (for example Alzheimer disease or Huntington's disease). Dementia is usually not associated with a change in level of consciousness, and a diagnosis of dementia requires a chronic impairment.
• Sundowning: Typically observed in patients suffering from dementia. It's an impairment in behavioral patterns in the evening hours. Similar symptomology can be observed in the patients suffering from other ailments such as impaired circardial rhythm. New onset in change in behavioral patterns should always be assessed carefully and diagnosis of delirium should be considered.

The difference between delirium and similar psychiatric illness

Attributes	Delirium	Alzheimer's disease	Depression	Psychotic Disorders
Onset	Sudden/acute/subacute	Gradual	Gradual	Acute or gradual
Progression	Shifts in severity, likely to resolve in days to weeks.	Worsens over period of time	Acute or chronic with acute exacerbation	Chronic with acute exacerbation
Hallucinations	May be present, mostly visual	Mostly absent (exceptions: Lewi body dementia, etc.)	May be present if associated with psychotic features	Present
Delusions	Fleeting	Mostly not present	May be present	Present
Psychomotar activity	Increased or decreased, may shift from increased to decreased states.	May or may not change	Change	Change
Attention	Poor attention span and impaired short term memory.	Progressive worsening short term memory. Attention span is likely to be affected in severe cases	May be altered	May be altered
Consciousness	Altered, rapidly shifts	Mostly intact until severe stages	Normal	Normal
Attention	Altered, rapidly shifts	Mostly intact until severe stages	May be altered	May be altered
Orientation	Altered, rapidly shifts	Mostly intact until severe stages	Not altered	Not altered
Speech	Not coherent	Errors	Slow	Normal or pressured
Thought	Disorganized	Impoverished	Normal	Disorganized
Perceptions	Altered, rapidly shifts	Mostly intact until severe stages	Normal	May be altered
EEG	Moderate to severe background slowing	Normal or mild diffuse slowing	Normal	Normal
Reversibility	Mostly	Very rarely	Yes	Rarely