The purpose of laboratory tests is to rule out other causes of cognitive decline, and to identify comorbid factors which aggravate cognitive disorders. By determining the serum vitamin B12 levels, deficiency can be ruled out. This is crucial as B12 deficiency state is described by cognitive complaints, irritability, and mood disorders. Determining mean corpuscular hemoglobin concentration (MCHC), simply put the amount of hemoglobin in red blood cells, also aids us in diagnosis. In vitamin B12 deficiency, the number of red blood cells decreases and their volume increases (so-called macrocytic anemia). Another set of parameters test thyroid function, such as TSH and T3, T4. In its underfunction (hypothyroidism) symptoms mimicking dementia may appear. A TSH determination is usually sufficient to rule out this condition. Liver function tests (AST, APT, GGT), rule out dysfunction which can also manifest with cognitive complaints. Blood sugar level, HbA1C and sugar balance can also be assessed, as diabetes is an important risk factor for dementia. The determination of total cholesterol, LDL cholesterol and HDL cholesterol levels can help to delineate cardiovascular risk factors. Elevated total cholesterol and LDL cholesterol are associated with an increased risk, while high HDL levels are associated with a reduced risk. In some cases, infectious diseases can also be diagnosed via blood serum levels such as HIV and syphilis, both of these cause severe cognitive impairment. Genetic analysis can also by done via serum testing, however this requires a special laboratory background. In such cases, we examine the genetic mutations most characteristic of the given disease (e.g. PSEN1 gene in the case of Alzheimer's disease), as well as those genetic changes that can significantly increase the risk of the disease (e.g. ApoE4 genotype).
Liquor or cerebrospinal fluid is a clear liquid produced in the ventricules of the central nervous system, which protects and nourishes the nerve tissue. The examination is performed with a lumbar puncture. The patient is in a seated, forward-bending position and a needle is inserted between the lower lumbar vertebrae. Following this a few ccs of fluid is collected from the cerebrospinal fluid space surrounding the end of spinal cord. It is important to know that the spinal cord cannot be damaged during the examination, as it terminates at a higher level, so the procedure is a safe and routinely used technique in neurology. After the test, we usually recommend a 24-hour inhospital observation. During the first hours bed rest is recommende, as headache may develop after the puncture, caused by a slight, temporary leakage of the fluid. With adequate fluid replacement and rest, the chance of this developing is low.Cerebrospinal fluid testing is suitable for the detection of abnormal proteins that accumulate in neurocognitive diseases, so we can essentially reach a complete diagnosis. Although the test is more burdensome for the patient compared to an MR scan, its diagnostic accuracy far exceeds that of an imaging test.