Every 3 seconds a person is diagnosed with dementia, leading to nearly 10 million new cases of dementia worldwide each year. Alzheimer’s Disease is the most common form of dementia and contributes to 60–70% of cases. Dementia with Lewy bodies comes 2nd, constituting 10-15% of all cases. Lewy body dementias are often difficult to distinguish from Alzheimer’s Disease in the early stages due to overlapping symptoms. Lewy body dementia patients are in many cases initially misdiagnosed as Alzheimer disease, Parkinson's disease or as a psychiatric disorder and tend to have numerous visits to many doctors before getting an accurate diagnosis.
For doctors, one of the concerns is that antipsychotic drugs, which can help Alzheimer’s patients, may have life- threatening side effects for Lewy body dementia patients. Mentis Cura’s Sigla can distinguish Lewy body dementias from other types of dementia with high accuracy.
The diagnoses of dementia and other causes of cognitive impairment are based on clinical signs and symptoms in addition to biological markers for those diseases. Doctors follow national or international guidelines when diagnosing dementia. Some of the methods in current use have the disadvantages of high cost (e.g. PET, SPECT) or being invasive (e.g. CSF). Sigla offers a simple, cost-effective, and non-invasive tool that complements existing protocols by combining a standard 5-minute EEG and statistical pattern analysis.
Sigla is an advanced and effective diagnostic aid for dementia that offers valuable support for dementia specialist making their diagnosis.
The pathologies of different types of dementia can vary greatly, but they all affect the electrophysiology of the brain, which is reflected directly in the EEG recording (electroencephalogram). Sigla analyses specific patterns in a patient’s EEG that indicate possible dementia and can help differentiate between Lewy body dementia and other types of dementia.
Sigla uses standard EEG recordings for the diagnosis and differentiation of dementia. Sigla is a user friendly software that produces results with high accuracy in a simple report within minutes, detailing two critical perspectives: The Dementia Index that helps clinicians rule out dementia and the Lewy body Index that differentiates Lewy body dementias from other types of dementia.
Sigla is a CE marked class 1 medical device and has been in routine clinical use since 2012.
The Dementia Index indicates whether an individual’s EEG signals resemble those of individuals suffering from dementia.
Any score below 50 is consistent with EEG signals from individuals with normal cognition and constitutes a negative result. The likelihood that a person receiving a negative result truly does not have dementia is 77%. Thus, the negative predictive value of the test is 77%.
The cut-off value at 50 is designed to correspond to 90% sensitivity. That means that at least 90% of true dementia cases should score 50 or above on the Dementia Index.
The specificity, however, is only 37%, meaning that many individuals with normal cognition will receive a score of 50 or higher on the Dementia Index. The likelihood that a person receiving a positive result truly does have dementia is 66%. Thus, the positive predictive value of the test is 66%.
For these reasons, the Dementia Index should not be used as a standalone test for diagnosing dementia.
The Lewy Body Index indicates whether an individual’s EEG signals resemble those of individuals suffering from Lewy body dementias and should be used to rule out or confirm Lewy body dementia.
Any score above 50 is consistent with EEG signals from individuals suffering from Lewy body dementia. The cut-off score 50 is designed to correspond to 90% sensitivity. The true sensitivity is 87 % meaning that at least 87% of true Lewy body dementia cases should score 50 or above on the Lewy Body Index.
The specificity of the test is 82%, meaning that of those not diagnosed with Lewy body dementia by the test 82% truly do not suffer from Lewy body dementia. The likelihood that a person receiving a negative result (score below 50) truly does not have Lewy body dementia is 98%. Thus, the negative predictive value of the test is 98%.
The likelihood that a person receiving a positive result truly does have Lewy body dementia is, however, 31%. Thus, the positive predictive value of the test is 31%. The low positive predictive value is linked to the relatively low prevalence of Lewy body dementia.
A 5 minute standard EEG is obtained using equipment that is already available at most hospitals and clinics while the patient rests comfortably.
The EEG is uploaded through a simple, user-friendly interface with existing hardware and processed in our cloud-based diagnostic software.
The software delivers documented results with actionable information in an easy-to-read report.
Sigla is indicated for use in the evaluation of adult patients between 50-90 years of age with suspected or verified dementia.
Sigla is intended to support other diagnostic evaluations and should not be used as a stand-alone instrument for diagnosing dementia.
The Sigla report should only be interpreted by qualified clinicians who are responsible for and experienced in providing dementia diagnosis.