Improvement of apathy after levofloxacin treatment: an N-of-1 study

Apathy is common in various neurological conditions. A caregiver of a patient with normal pressure hydrocephalus and cognitive decline repeatedly reported improvement in apathy, social interaction, and ability to perform activities of daily living after treatment with levofloxacin for upper respiratory infections. We sought to determine whether this effect could be objectively supported and replicated outside the context of infection.

An n-of-1 study was performed using 2 treatment and 2 nontreatment phases during an infection-free interval. Treatment arms consisted of 10-day courses of levofloxacin 500 mg daily. The evaluating investigator, caregiver, and patient were blind to treatment assignments. Measures included the Apathy Evaluation Scale (clinician and caregiver), Apathy Inventory (clinician and caregiver), Northwestern University Disability Scale, Disability Assessment for Dementia, and caregiver clinical global impression score.

The patient had less apathy and disability during 2 periods of treatment with levofloxacin 500 mg daily compared with periods without levofloxacin treatment. Caregiver clinical global impression scores were significantly better during days on treatment compared with off treatment (P=0.0007).

Evaluation of a single patient suggests that improvement in apathy may be a previously undescribed effect of levofloxacin. Further study is warranted.