Chronic Seizures Worsen Cognitive Function with Loss of Presenilin 2 Function in a Sex-Related Manner
Patients with early-onset Alzheimer's disease (EOAD) are at elevated risk for seizures, including patients with variants in presenilin 2 (PSEN2). Like patients with epilepsy, untreated seizures may also worsen cognitive function in AD. We therefore sought to define the impact of loss of normal PSEN2 function and chronic seizures on cognitive function in the aged brain. Male and female PSEN2 KO and age- and sex-matched wild-type (WT) mice were sham or corneal kindled beginning at 6-months-old. Kindled and sham-kindled mice were then challenged up to 6 weeks later in a battery of cognitive tests: non-habituated open field (OF), T-maze spontaneous alternation (TM), and Barnes maze (BM), followed by immunohistochemistry for markers of neuroinflammation and neuroplasticity. PSEN2 KO mice required significantly more stimulations to kindle (males: p<0.02; females: p<0.02). Chronic seizures more significantly worsened anxiety-like behaviors of female PSEN2 KO mice as measured by percentage of total time exploring the center of an OF. TM performance was significantly worsened in kindled female (p=0.024), but not male, PSEN2 KO mice. Male BM performance was generally worsened by seizures (p=0.038), but not by genotype. Conversely, kindled PSEN2 KO females made the most BM errors (p=0.007). Chronic seizures also significantly altered expression of hippocampal neuroinflammation and neuroplasticity markers in a sex-specific manner. This study demonstrates that hippocampus-dependent cognitive function may be only worsened by uncontrolled chronic seizures in female, but not male, PSEN2 KO mice. Our work aligns with clinical evidence of sex-specific worsening of AD burden and supports sex-specific anticonvulsant interventions in AD.