Diagnosis of cognitive impairment

When dementia is suspected, it is necessary to confirm it with the help of a family member or main caregiver. Family participation from the beginning is essential, even as a key part of discovering it. The diagnosis of dementia is fundamentally clinical, by taking a medical history and psychometric tests, speaking of a probability diagnosis. It is essential to carry out a clinical history in which the form of onset of the deterioration, the time and form of evolution, the initial symptoms and the current symptoms. It is essential that in this collection of information the patient is accompanied by a person from his immediate environment (informant) who can attest to the behavioral changes experienced by the patient from the beginning of the clinical picture to the present moment.

The physical examination should include weight, heart rate, and blood pressure, to obtain baseline data that can be compared with subsequent measurements, as well as the basic physical examination (cardiac, respiratory, abdominal, etc.).

The extent of the physical examination will be determined by the history and should always include a neurological examination that is as complete as possible.

Neuropsychological assessment is one of the most important activities in the diagnostic process of dementias. This assessment is made from:

• Brief cognitive scales. The screening instruments are short, accessible tests, of rapid application and without the need for great instructions, which provide initial and valuable information on the affectation of areas such as memory (immediate and delayed), language, praxis, abstract thinking, etc.
• Scales of functional evaluation. They allow estimating the impact of cognitive impairment on daily behavior and activities of daily living, both instrumental and basic.
• Brief and comprehensive neuropsychological batteries. In reality they are extensive cognitive scales that systematize a general assessment of mental state. Applied by specialists, they allow us to assess which areas are the most affected and allow the different types of dementia to be systematized, in addition to assessing components of depression or anxiety.

The complementary tests that are recommended to perform are basically to exclude treatable causes. As complementary tests, a blood and urine analysis should be carried out. A complete serum biochemistry should be performed including glucose, kidney and liver function, thyroid function, and vitamin B12. It is rare for dementia to be caused by hypothyroidism or a vitamin B12 deficiency, but both are common conditions for which treatment should be instituted. A complete blood count, syphilis serology should also be performed if the patient has specific risk factors (the Spanish Society of Neurology recommends its routine performance) and an elemental urinalysis. Neuroimaging techniques are both structural imaging techniques (computerized axial tomography (CT) or nuclear magnetic resonance imaging (NMR)), or functional imaging techniques (positron emission tomography (PET) and single photon emission computerized tomography). SPECT—). With these results, a differential diagnosis of other conditions that can cause cognitive alterations can be made, such as acute confusional syndrome (this basically due to the clinic) and depression. Once the diagnosis of suspected dementia is established, the doctor, preferably a specialist (geriatrician, neurologist), will make an etiological diagnosis, that is, will look for the most probable cause of the many diseases that can cause dementia in that patient. There are internationally agreed compliance criteria for the most important causes. Subsequently, it will establish a degree of severity that serves to know the prognosis, control the evolution, predict the response to the treatments and plan and make decisions. In the very near future, biological markers of certain dementias may appear. In this sense, Alzheimer's disease is the most widely investigated and for which authentic diagnostic markers have been postulated. Work is being done on possible genetic markers and other pathogenic markers such as certain proteins in blood and cerebrospinal fluid, such as the betaamyloid protein.