Dementia and delirium: Clinical

The brain is responsible for various mental functions, including memory, language, visuospatial function,  concentration, executive function, praxis, which is the ability to carry out complex motor activities, and personality. A subtle decline in cognitive function like a slowed reaction time, is a common part of normal aging, and usually doesn’t impair daily functioning and independence - this is called mild cognitive impairment. On the other hand, if there’s a decline in cognitive skill that does impair daily functioning and independence, then it’s called dementia. The major risk factor for most forms of dementia is advancing age, but dementia is not considered an inevitable consequence of normal aging. 

Most of the time, in dementia, a close family member or friend notices the individual’s change in cognition. This includes impaired memory, which leads to repeating conversations or misplacing belongings. Language impairment can make it hard to think of common words. Additionally, concentration and executive function are impaired, so individuals have a hard time with complex tasks, like managing their finances. Impairment in praxis leads to an inability to perform complex motor tasks, such as buttoning one’s shirt. Visuospatial impairment can lead to an inability with recognizing familiar faces or using simple instruments like utensils. Sometimes, family members will notice a change in the individual’s personality. To do a neurological examination, the Montreal cognitive assessment or MOCA or the mini-mental status examination, or MMSE, can be done to assess orientation, registration, recall, attention, and language. For example, orientation is assessed by asking individual what time it is, where they are, or who the president is. Registration is assessed telling the individual three words - like dog, table, and cake, and then asking them to repeat it immediately. Then, they’re asked to repeat those three names five minutes later, which assesses recall. Attention can be assessed by asking the individual to spell a word backwards. Language is tested by asking the individual to name presented objects, repeating a phrase, and following a 3-step command such as: “take this paper, fold it in half, and place it on the table”. Additionally, individuals are asked to obey a command written on a paper, such as “pick up the pen on the table”. Finally, individuals are asked to write a sentence and copy an illustration, such as a pentagon. The MMSE totals to 30 points, and a score of less than 24 implies cognitive impairment, which may suggest dementia or delirium, which can be differentiated by the time course and the clinical context. Now it’s important to differentiate delirium from dementia. Delirium is usually acute in onset, lasts only a couple of hours to days, and the cognitive symptoms fluctuate - meaning they come and go. On the other hand, dementia is usually gradual in onset, lasts months to years, and the cognitive symptoms are usually progress over time. Also consciousness and awareness are almost always impaired in delirium. However, they are only impaired in the later stages of dementia. Additionally, delirium usually  occurs in the event of an acute insult, such as an infection, electrolyte imbalance, change in medication or intoxication. It can also be due to a psychiatric condition, like schizophrenia or major depression. In fact, cognitive impairment associated with depression is called “pseudodementia”.