Sleep disruptions in patients with dementia significantly affected disease progression and complicated management of common comorbidities, according to a new study.

In the comprehensive review, published in Aging, investigators at Texas Tech University Health Sciences Center examined the relationships between dementia, sleep disorders, and concurrent medical conditions.

The investigators identified several key findings. For instance, up to 70% of patients with dementia experienced sleep disturbances, far exceeding prevalence in the general elderly population. Between 70% and 90% of patients with dementia had at least one comorbidity, with multiple conditions often coinciding.

The investigators discovered that cardiovascular disease represented a significant risk factor. Following ischemic stroke, approximately 125,000 new cases of vascular dementia occurred annually in the United States, with 25% to 41% of stroke survivors aged over 65 years developing vascular dementia within 3 months.

Diabetes emerged as another major risk factor. Type 2 diabetes was associated with a two- to threefold higher risk of developing dementia. Among study participants, 22.3% of the patients with dementia had diabetes, with insulin-treated diabetes showing a stronger association.

Mental health conditions frequently co-occurred. Depression affected 10% to 62% of the patients with dementia and 36% to 63% of those with mild cognitive impairment. Anxiety rates ranged from 8% to 71% in patients with dementia and 10% to 74% in those with mild cognitive impairment.

Sleep disorders proved particularly prevalent. The review found insomnia affected 5% to 15% of individuals, with chronic insomnia affecting 31% to 75% of patients. Self-reported insomnia complaints ranged from 30% to 60% among older adults. Patients with long-term insomnia using hypnotics faced more than twice the risk of developing dementia.

The researchers noted specific impacts across different comorbidities:

• Cardiovascular disease: Up to 90% of patients showed cognitive issues after coronary artery bypass graft surgery at discharge, while cognitive dysfunction affected 26% of elderly patients after major surgeries.
• Diabetes: The study found insulin-treated diabetes demonstrated a particularly strong connection to dementia development, especially vascular dementia.
• Anxiety/depression: Anxiety-specific disorders affected up to 49% of patients with dementia. Both subclinical hyperthyroidism and hypothyroidism were identified as risk factors for cognitive decline.

The investigators also examined treatment approaches. Light therapy showed effectiveness in managing sundowning symptoms through circadian regulation. Cognitive behavioral therapy demonstrated strong empirical support for chronic insomnia. However, the investigators found 79% of patients with restless leg syndrome received drugs that potentially worsened symptoms.

The study was supported by National Institutes of Health grant AG079264 and the Department of Internal Medicine at Texas Tech University Health Sciences Center.

The authors declared no conflicts of interest related to this study.