Global cognitive and verbal episodic memory impairment in the post-acute phase of anti-nmdar encephalitis: a systematic review and meta-analysis with narrative synthesis.

In 30 seconds

This systematic review and meta-analysis examined standardized cognitive outcomes in adults with cell-based-assay-confirmed anti-NMDAR encephalitis during the post-acute or convalescent phase. Fourteen observational cohorts included 439 patients. In the primary analysis, six cohorts comparing 191 patients with 182 healthy controls found substantial global cognitive impairment (Hedges’ g -1.26, 95% CI -1.49 to -1.04; I²=0%). Verbal episodic memory was also impaired (g -0.88, 95% CI -1.13 to -0.63; five cohorts). Narrative synthesis identified deficits in several other domains, while visuospatial findings were less consistent.

Key findings

• Global cognition was impaired versus healthy controls: Hedges’ g -1.26, 95% CI -1.49 to -1.04; I²=0%, across six cohorts.
• Verbal episodic memory was impaired: g -0.88, 95% CI -1.13 to -0.63, across five cohorts.
• Recognition was impaired alongside recall in the two cohorts reporting recognition trials.
• Narrative synthesis found frequent executive, working-memory, processing-speed, visual episodic memory, and language deficits; visuospatial findings were less consistent.

Why it matters

Cognitive difficulties may remain relevant after the acute encephalitis phase, and the pooled findings indicate that impairment extends beyond a single domain. Recognizing this broader pattern can inform assessment of ongoing cognitive needs and support attention to recovery over time. The review also highlights that the available evidence does not yet establish how these deficits change longitudinally.

What to keep in mind

The evidence came from observational cohorts, and only six cohorts contributed to the primary global-cognition analysis; several domains were synthesized narratively because fewer than three cohorts were available.