Doxycycline shows potential schizophrenia-lowering benefit

Psychiatric patients exposed to doxycycline appear to have a reduced risk of schizophrenia, according to a study.

Researchers used nationwide Finnish health register data and identified individuals who had accessed adolescent psychiatric services between ages 13 and 18 years and had used any antibiotics. These individuals were tracked from first dispensed antibiotic prescription up to age 30 years.

The primary outcome of schizophrenia diagnosis was evaluated across doxycycline exposure levels (cumulative dose doxycycline use: no use, low use at <1,499 mg, medium use at 1,500–2,999 mg, high use at ≥3,000 mg) during different follow-up periods.

The analysis included 56,395 individuals, of which 16,189 (28.7 percent) had been exposed to doxycycline.

Over 10 years of follow-up, the risk of schizophrenia was significantly lower among adolescent psychiatric patients who had been exposed to doxycycline than among their counterparts who had been exposed to non-doxycycline antibiotics. This was true across doxycycline exposure levels, namely low cumulative dose (1.4 percent vs 2.1 percent with non-doxycycline antibiotic exposure; risk ratio [RR], 0.70, 95 percent confidence interval [CI], 0.48–0.85), medium cumulative dose (1.4 percent vs 2.1 percent; RR, 0.65, 95 percent CI, 0.25–1.04; high cumulative dose: 1.5 percent vs 2.1 percent; RR, 0.70, 95 percent CI, 0.43–0.97).

These data point to the “exciting possibility” that doxycycline treatment may reduce schizophrenia risk in adolescent psychiatric patients, the researchers said.