Tests for diagnosing dementia

There is no single dementia test that can be used to diagnose such a complex syndrome. However a medical professional can use a number of tests and diagnostic procedures to assess an individual.

Assessing mental abilities to diagnose dementia

Questionnaires are commonly used to assess the cognitive abilities of individuals displaying symptoms of dementia. The mini mental state examination (MMSE) is a frequently used dementia test which helps to assess a number of mental capabilities. These include:
• long and short-term memory
• attention span
• concentration
• communication and language skills
• ability to organise and plan
• ability to comprehend instructions

The MMSE is a series of tasks with a maximum score of 30 points assigned to each. Examples of these exercises include:

  • Memorising a small list of items or objects and then repeating that list
  • Spelling a short word and then spelling it backwards
  • Reciting a short sentence and then having repeating it back
  • Copying a simple shape pattern

The MMSE is useful for assessing the degree of mental impairment an individual may have. It is not a definitive test of dementia as test scores can be influenced by a number of other factors such as the individual’s level of education. An individual with a higher level of education may score highly bit still have some form of dementia. Equally an individual with a lower level of education who has difficulties with reading and writing may score lower but not have dementia.

Blood tests for dementia

A blood test is often taken to rule out other conditions that may be responsible for the signs of dementia that an individual is displaying. Commonly these are associated to thyroid hormones or vitamin B12 levels.

Dementia brain scans

Brain scans are used to check for signs of damage to the brain. Certain types of dementia can be diagnosed from specific brain scans but they are also used to rule out other issues affecting the brain, such as a stroke or brain tumour, that may be responsible for the symptoms of dementia being displayed. The specific brain scans include:

Computerised Tomography (CT) scan

Commonly referred to as a CT scan, a computerised tomography scan can be used to check for signs of a brain tumour or a stroke.

However a CT scan cannot provide the same level of detailed information about the structure of the brain as an MRI scan.

Magnetic resonance imaging (MRI) scan

MRI stands for magnetic resonance imaging. This type of brain scan can help with the diagnosis of dementia as it provides more detailed information about the makeup and condition of the brain and in in particular the blood vessels within it. It is especially effective at helping diagnose vascular dementia which is caused by damage to these blood vessels within the brain. An MRI will also highlight any shrinking of the brain that is often seen in patients suffering with Alzheimer’s disease or frontotemporal dementia.

Other dementia tests

There are a number of other scans that can be used as part of the process of diagnosing dementia. If a CT or MRI scans are inconclusive then positron emission tomography (PET) or photon-emission computed tomography (SPECT) scan may be recommended. These scans offer an even more detailed picture of the brain and can show irregularities with the blood within the brain.

An electroencephalogram (EEG) may be recommended in some cases. This test can record the brain’s electrical signals (brain activity).

In some cases a lumbar puncture may also be undertaken. This procedure involves taking samples of spinal fluid to check the protein levels within the brain.