Tick-borne encephalitis leaves lasting cognitive scars, study finds

A new prospective study out of Norway is challenging the assumption that tick-borne encephalitis (TBE) is a short-lived illness. Researchers followed 109 hospitalized TBE patients and 80 matched controls over 12 months, using validated questionnaires to track memory, executive function, and overall symptom burden — and the results were striking.

At the one-year mark, TBE patients reported significantly more everyday memory difficulties and a heavier symptom burden than their healthy counterparts. Working memory was the standout cognitive domain affected. Factors like anxiety, depression, female sex, and greater acute disease severity were all tied to worse outcomes.

By the Numbers

• EMQ-R scores (everyday memory): 13.8 (patients) vs. 7.7 (controls), p <.001
• RPQ scores (symptom burden): 16.8 vs. 6.0, p <.001
• Patients were ~6x more likely to report clinically elevated memory difficulties (30.1% vs. 6.3%)
• Patients were ~8x more likely to report clinically elevated symptom burden (45.5% vs. 9.0%)

Why it matters

Clinicians may be too quick to declare TBE patients "recovered," especially after milder cases. This study makes a strong case for structured cognitive follow-up — including brief standardized tests and questionnaires — as a routine part of post-TBE care.