Declarative and Procedural Learning in Stroke, Parkinson's Disease and Sleep Apnea

Introduction: Both declarative and procedural learning show significant benefits from sleep in healthy people. We were interested in challenging this finding in those patients displaying structural damages to cerebral areas important for declarative memory (temporal lesions due to stroke, n=10) or non-declarative memory (diencephalic lesions due to Parkinson's disease, n=10) or chronic hypoxemic damage due to untreated sleep apnea (AHI >25/h, n=17). The investigations of healthy controls paralleled those of patients. Methods: Daytime learning over 30min, and 12 hours (from 8 a.m. to 8 p.m.) was compared intraindividually to nighttime learning (from 8 p.m. to 8 a.m.) including a spectrum of declarative (Verbal Learning Test, Rey Osterrieth Complex Figure Test, Wechsler Memory Scale) as well as procedural tasks such as the reading of mirror printing as well as full recording of sleep by polysomnography in the nights „after learning“ and the nights „under learning“. Psychometric Results: Healthy volunteers showed significantly better results after nighttime learning than after daytime learning, which validates the experimental design of this study. All patients showed better learning over night than at day, i.e., their learning benefits from sleep in spite of structural or hypoxemic damage. This benefit, however, is not as great as in healthy volunteers. The sleep benefit in patients with „declarative lesions“ was significant for procedural learning only; in patients with non-declarative lesions it was seen for declarative learning only, but this differential effect is below significance. In patients with untreated sleep apnea investigated until now it is not significantly lower than in controls. Polysomnographic Results: In comparison to the night „after learning“ the sleep pattern of the night „under learning“ shows no changes in healthy controls, a significant increase of stages 3 + 4 in stroke patients with lesions of declarative memory, almost significant increases of stage REMS in Parkinsonian patients with deficits of procedural memory. Results of learning in sleep after therapy with nCPAP are underway and will be presented.