January 2026 Research Update

This month added clearer information about which nonseizure measures are practical for CDKL5 deficiency disorder (CDD) research and which ones may miss important differences. Across ages, many participants scored at the very bottom of one motor scale, meaning it could fail to capture change even if a person improves. In contrast, several everyday-function and development measures could be completed and sometimes showed age-related gains in specific skills, supporting their use in future studies. [1]

The strongest limitation was seen with the Gross Motor Function Measure (GMFM-88), where crawling, standing, and walking sections showed floor effects across ages. In plain language, many people were already scoring as low as the test allows, so the test could not reliably separate levels of ability or detect improvement. This matters because a measure that cannot move up from the bottom is unlikely to be useful as a main outcome in clinical trials. [1]

Other tools appeared more workable for capturing differences beyond seizures, including caregiver-reported daily functioning (Vineland-3) and early development testing (Bayley-4), where some areas showed age-related gains such as receptive language and certain social and motor domains. The same study also documented common real-world challenges at baseline, including sleep difficulties and reduced independence in activities like dressing and feeding. Taken together, these results build a more realistic picture of what can be measured in CDD studies and where measurement gaps still exist. [1]

For families, this mainly affects research planning rather than day-to-day care right now. It helps explain why some study results can be hard to interpret if the chosen test is not sensitive enough for CDD, especially for motor skills where many people may score at the bottom of a scale. It also supports the idea that research can track more than seizures using feasible caregiver reports and development measures, but it remains uncertain which measures are best at showing meaningful change over time for every person. [1]

This month strengthened the picture that sleep problems in CDD are not just one issue, and they often come alongside other challenges. Across a large group, different kinds of sleep disruption were reported, including trouble falling asleep, nighttime awakenings, breathing-related sleep symptoms, and sleep-wake transitions. Reports of sleep difficulties also tended to differ by age and by day-to-day health and functioning factors, showing that sleep in CDD may be shaped by multiple parts of a person s overall condition. [2]

Several specific patterns were reported in the database analysis. Daily seizures were linked to lower scores for sleep initiation and maintenance but higher scores for sleep breathing problems, and night-time seizures were linked to more disrupted sleep-wake transitions. Constipation was connected with higher odds of more severe sleep initiation and maintenance problems, and higher emotional or disruptive behavior was linked with worse sleep initiation and more daytime sleepiness. [2]

Caregiver comments added detail about what sleep disruption can look like in real life, including insomnia, periods of being awake and active at night, and daytime sleepiness. Families also described possible contributors such as seizure timing, reflux or constipation, and effects of anti-seizure medicines on sleep. A minority had formal sleep testing reported, and some were diagnosed with sleep apnea, showing that breathing-related sleep issues can be part of the picture for at least some people. [2]

For patients and caregivers, this adds practical understanding of why sleep in CDD can be difficult to manage and why it can look different from one person to another. The evidence here comes from caregiver-reported data in a database, so it cannot prove that seizures, constipation, or behavior cause sleep problems, but it does clarify that these issues often travel together. This matters mostly now for understanding and for research, because it points to sleep as a meaningful part of quality of life in CDD and highlights areas that future studies may target or measure more carefully. [2]