Under-recognised neurocognitive deficits in adults and adolescents with tuberous sclerosis complex

Background: Tuberous sclerosis complex (TSC) is a genetic disease characterised by the growth of benign tumours. The Tuberous sclerosis Associated Neuropsychiatric Disorders (TAND) Checklist is used to identify patient-reported neurocognitive deficits. Patients may, however, under-recognise mild cognitive impairment. We aimed to determine the frequency of abnormal scores on three objective tests of cognitive function in people with and without diagnosed intellectual disability and examine associations between scores on these tests with self-reported TAND Checklist symptoms.

Methods: We conducted a cross-sectional study where people with TSC (PwTSC; n=46) completed the TAND Checklist and three cognitive tests: Symbol Digit Modalities Test (SDMT), Montreal Cognitive Assessment test and Trail Making Test-Parts A and B. We examined associations between cognitive test scores and the TAND Checklist using Pearson's correlations (95% CI). Receiver operating characteristics (ROC) curves were plotted to determine the screening accuracy of each measure in identifying physician-diagnosed neurocognitive disorders.

Results: There were minimal correlations between the cognitive test scores and the TAND Checklist. More than 20% of PwTSC reported no cognitive issues on the TAND Checklist but had abnormal performance on at least one cognitive test. The ROC curves demonstrated similar results, with areas under the curve of 0.93 (95% CI 0.79 to 1.00) for the SDMT but only 0.70 (95% CI 0.45 to 0.95) for the TAND Checklist.

Conclusion: Objective tests of cognitive function are useful in identifying unrecognised neurocognitive deficits in PwTSC. Deficits likely have multifactorial origins, including undiagnosed intellectual disability and the impact of chronic epilepsy.