for at least six months to support a diagnosis. Cognitive dysfunction of shorter duration is called delirium. Delirium can be easily confused with dementia due to similar symptoms. Delirium is characterized by a sudden onset, fluctuating course, a short duration (often lasting from hours to weeks), and is primarily related to a somatic (or medical) disturbance. In comparison, dementia has typically a long, slow onset (except in the cases of a stroke or trauma), slow decline of mental functioning, as well as a longer trajectory (from months to years). Some mental illnesses, including depression and psychosis, may produce symptoms that must be differentiated from both delirium and dementia. These are differently diagnosed as pseudodementias, and any dementia evaluation needs to include a depression screening such as the Neuropsychiatric Inventory or the Geriatric Depression Scale. Physicians used to think that people with memory complaints had depression and not dementia (because they thought that those with dementia are generally unaware of their memory problems). However, researchers have realized that many older people with memory complaints in fact have mild cognitive impairment the earliest stage of dementia. Depression should always remain high on the list of possibilities, however, for an elderly person with memory trouble. Changes in thinking, hearing and vision are associated with normal ageing and can cause problems when diagnosing dementia due to the similarities. Given the challenging nature of predicting the onset of dementia and making a dementia diagnosis clinical decision making aids underpinned by machine learning and artificial intelligence have the potential to enhance clinical practice. Cognitive testing Various brief cognitive tests (5–15 minutes) have reasonable reliability to screen for dementia, but may be affected by factors such as age, education and ethnicity. Age and education have a significant influence on the diagnosis of dementia. For example, Individuals with lower education are more likely to be diagnosed with dementia than their educated counterparts. While many tests have been studied, presently the mini mental state examination (MMSE) is the best studied and most commonly used. The MMSE is a useful tool for helping to diagnose dementia if the results are interpreted along with an assessment of a person's personality, their ability to perform activities of daily living, and their behaviour. Other cognitive tests include the abbreviated mental test score (AMTS), the, Modified Mini-Mental State Examination (3MS), the Cognitive Abilities Screening Instrument (CASI), the Trail-making test, and the clock drawing test.