Cognitive impairment and dementia update

12:12 pm Health Care, Medicine, Social Health Community

 Suresh Kalmadi is suffering from dementia. This has given us an opportunity to revise the subject of dementia.

What is dementia?

Dementia is a disorder characterized by impairment of memory and at least one other cognitive domain (aphasia, apraxia, agnosia, executive function). These must represent a decline from previous level of function and be severe enough to interfere with daily function and independence.

What are cognitive functions?

The cognitive functions are: Memory, reasoning, language, calculations and spatial orientation.

How common is dementia?

About 5 % of individuals over age 65 years and 35-50 % of persons over age 85 years have dementia; the pretest probability of dementia in an older person with reported memory loss is estimated to be at least 60 %.

What are dementia syndromes?

The major dementia syndromes include

  • Alzheimer’s disease
  • Dementia with Lewy bodies
  • Frontotemporal dementia
  • Vascular (multi-infarct) dementia
  • Parkinson’s disease with dementia

What is Alzheimer’s disease?

Alzheimer’s disease is the most common form of dementia in the elderly, accounting for 60-80 % of cases.

What is DSM-IV definition of dementia?

Evidence from the history and mental status examination that indicates major impairment in learning and memory as well as at least one of the following:

  • Impairment in handling complex tasks (e.g., balancing a checkbook)
  • Impairment in reasoning ability (e.g., unable to cope with unexpected events)
  • Impaired spatial ability and orientation (getting lost in familiar places)
  • Impaired language (word finding)

The cognitive symptoms must significantly interfere with the individual’s work performance, usual social activities, or relationships with other people. There must be a significant decline from a previous level of functioning. The disturbances are of insidious onset and are progressive. The disturbances are not due to delirium (a major psychiatric diagnosis), systemic disease or another brain disease.

Patients with dementia may also have difficulty with

  • Learning and retaining new information (e.g., trouble remembering events)
  • Behavior

Who reports dementia in a patient?

Most patients with dementia do not present with a complaint of memory loss; it is often a spouse or other informant who brings the problem to the physician’s attention.

What is age-related cognitive decline?

The normal cognitive decline associated with aging consists primarily of mild changes in memory and the rate of information processing, which is not progressive and does not affect daily function. Learning or acquisition performance decline uniformly with age. Delayed recall or forgetting remains relatively stable. Aging is associated with a decline in the acquisition and early retrieval of new information but not in memory retention.

What is mild cognitive impairment?

Mild cognitive impairment is the presence of memory difficulty and objective memory impairment but preserved ability to function in daily life. These patients appear to be at increased risk of dementia.

Should these patient be screened for B12 levels?

The American Academy of Neurology  recommends screening for B12 deficiency and hypothyroidism in patients with dementia.

Should MRI be done in all cases?

Neuroimaging rules out patients who might have reversible causes of dementia that can be diagnosed with imaging studies (subdural hematoma, normal pressure hydrocephalus, treatable cancer). Structural neuroimaging with either a non-contrast head CT or MRI should be considered in the initial evaluation of all patients with dementia.

Is there a role of biopsy?

Brain biopsy has a very limited role in the diagnosis of dementia.

What is the association with depression?

Screening for depression in patients with dementia is recommended because depression is a common treatable co-morbidity that may also masquerade as dementia.

What is Mini-Mental State Examination?

Mini-Mental State Examination (MMSE) is the most widely used cognitive test for dementia. The examination takes approximately 7 minutes to complete. It tests a broad range of cognitive functions including orientation, recall, attention, calculation, language manipulation, and constructional praxis.

The MMSE includes the following tasks:

  • What is the date: (year)(season)(date)(day)(month) – 5 points
  • Where are we: (state)(county)(town)(hospital)(floor) - 5 points
  • Name three objects: Ask the patient all three after you have said them. Give one point for each correct answer. Then repeat them until he/she learns all three. Count trials and record. The first repetition determines the score, but if the patient cannot learn the words after six trials then recall cannot be meaningfully tested. Maximum score – 3 points.
  • Serial 7s, beginning with 100 and counting backward: one point for each correct; stop after five answers. Alternatively, spell WORLD backwards: one point for each letter in correct order. Maximum score – 5 points.
  • Ask for the three objects repeated above: one point for each correct answer. Maximum score – 3 points.
  • Show and ask patient to name a pencil and wrist watch – 2 points.
  • Repeat the following, “No ifs, ands, or buts.” Allow only one trial – 1 point.
  • Follow a three stage command, “Take a paper in your right hand, fold it in half, and put it on the floor.” Score one point for each task executed. Maximum score – 3 points.
  • On a blank piece of paper write “close your eyes;” ask the patient to read and do what it says – 1 point.
  • Give the patient a blank piece of paper and ask him/her to write a sentence. The sentence must contain a noun and verb and be sensible – 1 point.
  • Ask the patient to copy a design (e.g., intersecting pentagons). All 10 angles must be present and two must intersect – 1 point.

A total maximal score on the MMSE is 30 points.

A score of less than 24 points is suggestive of dementia or delirium.

Using a cutoff of 24 points, the MMSE had a sensitivity of 87 % and a specificity of 82 %.

The test is not sensitive for mild dementia, and scores may be influenced by age and education, as well as language, motor, and visual impairments.

For research purposes, some investigators use a cutoff score of 26 or 27 in symptomatic populations in order to not miss few true cases.

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