BioCog Test: Ten Minutes to Orient Yourself in a Patient’s Cognitive Status

Early AD Diagnosis in the General Practitioner’s Office

Diagnosing Alzheimer’s disease (AD) in primary care is challenging, especially in its early stages. Paper-based tests show limited accuracy, and their results depend on the approach and experience of the examiner.

Modern blood biomarkers, such as p-tau217, can significantly improve AD detection. However, their use is mainly recommended for individuals with objectively confirmed cognitive impairment. In patients who report memory or attention problems but perform within normal limits on testing, the risk of false-positive results is higher.

Therefore, identifying objectively measurable cognitive impairment should precede the indication for biomarker testing. For this purpose, the short digital test battery BioCog was developed, which patients can complete independently on a tablet. It is capable of detecting cognitive impairment even in primary care and, when combined with a blood biomarker, can substantially improve the identification of patients with clinical AD.

BioCog consists of three main components: repeated learning and delayed recall of a 10-word list, a task assessing cognitive processing speed, and questions evaluating time orientation. Completion takes approximately 11 minutes.

Study Populations

Data from 223 individuals in secondary care were used to develop the BioCog diagnostic model. The model was then tested in 403 patients examined by general practitioners for suspected neurodegenerative disease.

Participants in primary care were older, had lower educational attainment, and a higher prevalence of comorbidities, more closely reflecting a typical clinical population. Objective cognitive impairment was determined using the RBANS neuropsychological test or its equivalent.

Model Development in Secondary Care

A logistic regression model, BioCog6, was created from individual BioCog test components and demographic data. It primarily included delayed word recall and cognitive processing speed. In secondary care, the model detected cognitive impairment with an accuracy of approximately 89%.

The authors also established two diagnostic thresholds. Individuals whose results fell between these thresholds were referred for additional neuropsychological assessment.

Validation in Primary Care

The accuracy of the BioCog6 model during validation in primary care was 85%. This outperformed assessment by general practitioners (approximately 73%), commonly used paper-based tests (Mini-Mental State Examination, Montreal Cognitive Assessment, Mini-Cog), as well as another digital test (CANTAB). When using two diagnostic thresholds, accuracy increased to 90%, with approximately 18% of individuals classified into an indeterminate zone.

According to the authors, BioCog can provide a more accurate and standardized assessment of cognitive status than commonly available tests and may help identify individuals who require further evaluation or biomarker testing.

Combining the Digital Test With a Blood Biomarker

In a two-step diagnostic approach, the blood biomarker was used only in patients with cognitive impairment identified by BioCog. The combination of the digital test and the p-tau217 biomarker achieved an accuracy of 90% in identifying clinical Alzheimer’s disease. This exceeded both the accuracy of general practitioner assessment and that of the biomarker alone.

Integration Into Standard Diagnostics

The digital BioCog test may serve as an effective tool for identifying objective cognitive impairment and offers higher accuracy than commonly used tests. When combined with the blood biomarker p-tau217, it enabled reliable diagnosis of clinical AD and outperformed standard clinical assessment.

The authors note that digital cognitive tests can improve standardization and efficiency in diagnostics. BioCog is intended to complement, not replace, clinical decision-making. They further recommend its integration into structured diagnostic pathways and validation across multiple languages and cultural settings.

Editorial Team, Medscope.pro

Source:

Tideman P., Karlsson L., Strandberg O. et al. Primary care detection of Alzheimer’s disease using a self-administered digital cognitive test and blood biomarkers. Nat Med 2025, doi: 10.1038/s41591-025-03965-4.