Insomnia is a common sleep disorder among older adults, and a risk factor for poor physical and mental health. However, the relationship between insomnia and cognitive health is not well understood. Here, we review observational studies that have investigated whether insomnia is associated with deficits in objective cognitive performance and an increased risk of dementia, magnetic resonance imaging studies that have assessed grey matter volumes and white matter microstructure, and interventional studies that have explored whether the treatment of insomnia can improve cognitive outcomes. There are inconsistent findings regarding impaired performance in objective cognitive tests and reduced grey matter volumes, and limited, emerging, evidence that suggests that insomnia is associated with an increased risk of dementia and reduced white matter integrity. Although the interventional literature is still in its infancy, there is some indication that treatment may have an impact on vigilance. Well-powered studies examining sources of heterogeneity are warranted.

Background Cognitive Behavioral Sleep Medicine is a rapidly growing discipline that aims at the comprehensive evaluation and treatment of people with cognitive or sleep symptoms, established on the bidirectional relationship between sleep disorders and neurodegeneration. On this basis, we established a comprehensive evaluation protocol for deep phenotyping of cognitive‐sleep syndromes, and present first results on its feasibility and novel cognitive to sleep associations. Method We enrolled 29 patients (age: 71.5 ± 11.7; education: 9.6 ± 2.8 years) with minor or major neurocognitive disorder due to predicted Alzheimer’s disease with various degrees of vascular comorbidity (MMSE = 26.0 ± 4.3) through the Sleep & Memory Center of the Neurological Institute of Athens. All patients underwent comprehensive clinical evaluations, including cognitive (Cognitive Behavioral Symptoms [CBS] score) and sleep questionnaires (Insomnia Severity Index [ISI]; Epworth Sleepiness Scale [ESS]), biochemical, imaging, and within‐day neuropsychological testing, whereas six patients have further completed novel sleep‐mediated neuropsychological tests, actigraphy and polysomnography. Exploratory analyses using Pearson ρ or Kendall τ, accordingly, were performed to examine associations of subjective complaints and daily functioning to objective cognitive and sleep metrics. Result Non‐memory cognitive CBS scores were highly correlated to sleep CBS scores (ρ,τ ∼ 0.51 ‐ 0.71), as well as ISI (0.56) and ESS (0.54). Memory CBS complaints in contrast correlated more with subjective insomnia symptoms (0.72 to ISI) but not hypersomnia (‐0.15 to ESS). Additionally, the CBS total score was associated to sleep‐mediated 9‐item recall (0.81) and to sleep‐mediated phonemic fluency (‐0.55), an association also noted between ESS to sleep‐mediated 9‐item recall (0.71). Of note, subjective cognitive and sleep complaints were not well correlated to within‐day neuropsychological testing (e.g., 0.13 ‐ 0.36 to MMSE). Patients who underwent actigraphy and polysomnography tolerated all procedures, and those diagnosed with sleep apnea or insomnia are effectively pursuing CPAP treatment and Cognitive Behavioral Therapy for Insomnia respectively. Conclusion Comprehensive evaluation of sleep and cognitive symptoms is feasible in patients with neurocognitive disorders and allows for deep phenotyping of neurodegenerative diseases. Finally, sleep‐mediated cognitive tests seem to be more sensitive than within‐day tests in reflecting real‐life symptoms, highlighting their potential utility.

Background The demand for specialized care in neurocognitive disorders greatly surpasses its availability. Patients have complex needs and specialists are scarce. As a result, there is a gap between the needs of patients and the capacity of health systems to address them. Expert systems help fill this gap working towards early and accurate phenotyping (description) of neurocognitive disorders to better identify and successfully allocate the limited resources. We developed the Cognitive Behavioral Score (CBS), a 51‐item structured self‐administered questionnaire and its caregiver counterpart (cCBS), conducting exploratory analyses on clinical feasibility and diagnostic utility, as well as association to neuropsychological performance. Method We enrolled 29 patients (age: 71.5±11.7; education: 9.6±2.8 years) with minor or major neurocognitive disorder (late age‐of‐onset Alzheimer’s disease with various degrees of vascular comorbidity; MMSE= 26.0±4.3) through the Sleep & Memory Center of the Neurological Institute of Athens. CBS and cCBS were completed by patients and/or their caregivers, covering cognitive, behavior, autonomic, and sleep symptom severity and duration. Patients underwent physical examinations, neuropsychological, biochemical and imaging testing. Statistical analyses were conducted using Pearson ρ or Kendall τ as appropriate, depending on data deviation from normality. Results Both CBS and cCBS were completed in‐clinic or at home within 5 minutes and provided a clinical overview of symptom progression. CBS and cCBS congruence total score was 0.36, certain domain‐specific sub scores were even better (0.46 – 0.67). Correlation to MMSE was better for cCBS (‐0.30), a feature reflective of the patient population. CBS and cCBS sub scores had varying degrees of correlation to domain‐specific neuropsychological tests, with historic symptoms of anomia having most and highest associations (≤ ‐0.76). Non‐cognitive symptoms were correlated to executive function, hinting to possible comorbid synucleinopathies or sleep deprivation. Conclusion The study results suggest that both CBS and cCBS have diagnostic utility for the clinician. They allow faster and more accurate description and identification of syndromic neurocognitive disorders. With better understanding, resources can be allocated in a more directed and better‐planned manner, helping low resource settings. Also these questionnaires minimize the time in history taking, allowing health professionals to dedicate more time to the patients for better and individualized care.