By Dr Ananya Mandal, MD
Amnesia or memory loss can be transient or short term and may have a sudden or gradual onset and worsening.
With age most people tend to lose memory. However, when memory loss tends to interfere with activities of daily living, a more careful evaluation is warranted.
In many of these pathological cases forgetfulness becomes frequent and consistent and becomes cause for concern.
Assessment of amnesia
Assessment and diagnosis of amnesia and its cause involve (1-4):
- Detailed look at medical and mental health history of the patient. Many patients presenting with memory loss suffer from other conditions like stress, anxiety and depression.
- A detailed family history of memory related conditions like Alzheimer’s disease etc. is enquired.
- Questions are asked regarding frequency of memory lapses, types of things forgotten, repetition of same phrases or questions in the same conversation, forgetting routine tasks—like brushing, bathing etc.
Patients are assessed for confusion, trouble in decision making, judgement and handling money.
Anterograde amnesia or loss of memory about events that occurred before a specific experience or retrograde amnesia or loss of memory about events that occurred soon after a specific experience is differentiated and detected. It is seen if memory loss is short term or long term.
- History of triggering factors is enquired. This includes history of head injury in the recent past, an emotionally traumatic event in the recent past, recent requirement of a surgery under general anaesthesia, history of illicit drug or alcohol abuse.
- A detailed physical examination is performed next to assess for different causes of amnesia.
For example, in Korsakoff’s psychosis that occurs due to long term alcohol abuse also leads to numbness and loss of sensation in the fingers and toes.
There is also a symptom of confabulation in Korsakoff’s psychosis when patient fills up gaps in his memory by making up information on his or her own.
Tests for amnesia
Tests for amnesia include blood tests, brain scans and so forth.
Blood tests for amnesia
Blood tests include:
- Tests for low thyroid function. This is done by assessment of thyroid hormone.
- Low vitamin B12 may also be detected by blood tests.
- Routine blood tests assessing total blood count, liver and kidney functions are often prescribed for diagnosis of cause of memory loss
Brain scans for amnesia
A CT scan or MRI of the brain is often prescribed. This is done to detect a stroke, bleeding inside the brain or head injury that may have led to amnesia.
Other tests for amnesia
Other tests for amnesia include Cerebral angiography, EEG and so forth.
- A Cerebral angiography may be prescribed.
This test includes injection of a special dye via a vein in the arm. This travels to the blood vessels of the brain and the image is recorded. This gives a idea regarding a brain bleeding or stroke that may have led to the memory loss.
Other imaging studies include magnetoencephalography and PET scan.
- EEG or electroencephalogram is prescribed to detect abnormal electric activities in the brain. These are often diagnostic of epilepsy.
- An infection or other brain pathology may be detected using assessment of the Cerebrospinal fluid by lumbar puncture.
- Most important method of diagnosis includes psychometric tests or cognitive tests.
There are numerous tools that are used to diagnose amnesia. These involve series or questionnaires and verbal, audiovisual or visual tests to detect the extent of memory loss.
The most used tool is the Mini Mental State Examination (MMSE). It is most commonly used to diagnose memory loss.
Another test is the Six Item Cognitive Impairment Test (6CIT) or the Kingshill test.
For memory loss related to aging especially in the hospital settings commonly used test is the Abbreviated Mental Test (AMT).
Edited by April Cashin-Garbutt, BA Hons (Cantab)
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