Clinicopathologic Dissociation: Robust Lafora Body Accumulation in Malin KO Mice Without Observable Changes in Home-Cage Behavior.

Lafora disease (LD) is a syndrome of progressive myoclonic epilepsy and cumulative neurocognitive deterioration caused by recessively inherited genetic lesions of EPM2A (laforin) or NHLRC1 (malin). Neuropsychiatric symptomatology in LD is thought to be directly downstream of neuronal and astrocytic polyglucosan aggregates, termed Lafora bodies (LBs), which faithfully accumulate in an age-dependent manner in all mouse models of LD. In this study, we applied home-cage monitoring to examine the extent of neurobehavioral deterioration in a model of malin-deficient LD as a means to identify robust preclinical endpoints that may guide the selection of novel genetic treatments. At 6 weeks, ∼6-7 months, and ∼12 months of age, malin-deficient mice ("KO") and wild-type (WT) littermates underwent a standardized home-cage behavioral assessment designed to non-obtrusively appraise features of rest/arousal, consumptive behaviors, risk aversion, and voluntary wheel-running. At all timepoints, and over a range of metrics that we report transparently, WT and KO mice were essentially indistinguishable. In contrast, within WT mice compared across the same timepoints, we identified age-related nocturnal hypoactivity, diminished sucrose preference, and reduced wheel-running. Neuropathological examinations in subsets of the same mice revealed expected age-dependent LB accumulation, gliosis, and microglial activation in cortical and subcortical brain regions. At 12 months of age, despite the burden of neocortical LBs, we did not identify spontaneous seizures during an electroencephalographic (EEG) survey, and KO and WT mice exhibited similar spectral EEG features. However, in an in vitro assay of neocortical function, paroxysmal bursts of network activity (UP states) in KO slices were more prolonged at 3 and 6 months of age, but similar to WT at 12 months. KO mice displayed a distinct response to pentylenetetrazole, with a greater incidence of clonic seizures and a more pronounced postictal suppression of movement, feeding, and drinking behavior. Together, these results highlight the clinicopathologic dissociation in a mouse model of LD, where the accrual of LBs may latently modify cortical circuit function and seizure threshold without clinically meaningful changes in home-cage behavior. Our findings allude to a delay between LB accumulation and neurobehavioral decline in LD: one that may provide a window for treatment, and whose precise duration may be difficult to ascertain within the typical lifespan of a laboratory mouse.

Clinicopathologic Dissociation: Robust Lafora Body Accumulation in Malin KO Mice Without Observable Changes in Home-cage Behavior.

Lafora Disease (LD) is a syndrome of progressive myoclonic epilepsy and cumulative neurocognitive deterioration caused by recessively inherited genetic lesions of EPM2A (laforin) or NHLRC1 (malin). Neuropsychiatric symptomatology in LD is thought to be directly downstream of neuronal and astrocytic polyglucosan aggregates, termed Lafora bodies (LBs), which faithfully accumulate in an age-dependent manner in all mouse models of LD. In this study, we applied home-cage monitoring to examine the extent of neurobehavioral deterioration in a model of malin-deficient LD, as a means to identify robust preclinical endpoints that may guide the selection of novel genetic treatments. At 6 weeks, ~6-7 months and ~12 months of age, malin deficient mice ("KO") and wild type (WT) littermates underwent a standardized home-cage behavioral assessment designed to non-obtrusively appraise features of rest/arousal, consumptive behaviors, risk aversion and voluntary wheel-running. At all timepoints, and over a range of metrics that we report transparently, WT and KO mice were essentially indistinguishable. In contrast, within WT mice compared across timepoints, we identified age-related nocturnal hypoactivity, diminished sucrose preference and reduced wheel-running. Neuropathological examinations in subsets of the same mice revealed expected age dependent LB accumulation, gliosis and microglial activation in cortical and subcortical brain regions. At 12 months of age, despite the burden of neocortical LBs, we did not identify spontaneous seizures during an electroencephalographic (EEG) survey, and KO and WT mice exhibited similar spectral EEG features. Using an in vitro assay of neocortical function, paroxysmal increases in network activity (UP states) in KO slices were more prolonged at 3 and 6 months of age, but were similar to WT at 12 months. KO mice displayed a distinct response to pentylenetetrazole, with a greater incidence of clonic seizures and a more pronounced post-ictal suppression of movement, feeding and drinking behavior. Together, these results highlight a stark clinicopathologic dissociation in a mouse model of LD, where LBs accrue substantially without clinically meaningful changes in overall wellbeing. Our findings allude to a delay between LB accumulation and neurobehavioral decline: one that may provide a window for treatment, and whose precise duration may be difficult to ascertain within the typical lifespan of a laboratory mouse.

Actigraphic correlates of neuropsychiatric symptoms in adults with focal epilepsy.

OBJECTIVES: Disability in patients with epilepsy (PWEs) is multifactorial: beyond seizure frequency/severity, PWEs are prone to a range of neuropsychiatric, cognitive, and somatic comorbidities that significantly affect quality of life. Here, we explored how variations in seizure severity and the burden of self-reported somatic/neuropsychiatric symptoms correlate with disruptions to 24 h activity patterns (rest-activity rhythms [RARs]), determined through wrist accelerometry/actigraphy. METHODS: Multiday wrist-actigraphy recordings were obtained from 59 adult patients with focal epilepsy (44% male, ages 18-72), who contemporaneously responded to validated psychometric instruments to measure anxiety, depression, sleepiness, and somatic symptoms. We conducted a similar in silico psychometric-actigraphic correlation in a publicly available data set of 1747 Hispanic subjects (35% male, ages 18-65) from the Study of Latinos (SOL) Sueño Ancillary Study. RARs were analyzed via a sigmoidally-transformed cosine model (quantifying amplitude, steepness, acrophase, and robustness) and nonparametric measures to estimate RAR stability, fragmentation, and sleep. RESULTS: Compared with matched SOL subjects, RARs from PWE subjects featured a significantly lower amplitude, a wider rest phase, and significantly more total daily sleep. Within PWEs, similar RAR distortions were associated with seizure intractability and/or anticonvulsant polytherapy, whereas high anxiety, depression, and somatic symptom scores were associated with lower RAR robustness and acrophase delay. We applied the SOL data set to train logistic regression models to dichotomously classify subjective anxiety, depression, and sleepiness symptoms using demographic and RAR parameters. When tested on PWEs, these models predicted prevalent anxiety and depression symptom burden (accuracy ~70%) but failed to predict subjective sleepiness. SIGNIFICANCE: Together these results demonstrate that RAR features may encode prevalent depression and anxiety symptoms in patients with focal epilepsy, potentially offering wearable-derived endpoints to adjunct clinical care and drug/device trials. With larger PWE-specific actigraphic-psychometric data sets, we may identify RAR signatures that may more precisely correlate with varying seizure frequency, the burden of anticonvulsant therapy, and prevalent mood/anxiety symptoms.

Home-cage behavior in the Stargazer mutant mouse.

In many childhood-onset genetic epilepsies, seizures are accompanied by neurobehavioral impairments and motor disability. In the Stargazer mutant mouse, genetic disruptions of Cacng2 result in absence-like spike-wave seizures, cerebellar gait ataxia and vestibular dysfunction, which limit traditional approaches to behavioral phenotyping. Here, we combine videotracking and instrumented home-cage monitoring to resolve the neurobehavioral facets of the murine Stargazer syndrome. We find that despite their gait ataxia, stargazer mutants display horizontal hyperactivity and variable rates of repetitive circling behavior. While feeding rhythms, circadian or ultradian oscillations in activity are unchanged, mutants exhibit fragmented bouts of behaviorally defined "sleep", atypical licking dynamics and lowered sucrose preference. Mutants also display an attenuated response to visual and auditory home-cage perturbations, together with profound reductions in voluntary wheel-running. Our results reveal that the seizures and ataxia of Stargazer mutants occur in the context of a more pervasive behavioral syndrome with elements of encephalopathy, repetitive behavior and anhedonia. These findings expand our understanding of the function of Cacng2.