Sleep to Prevent Cognitive Decline

Getting enough sleep may help prevent cognitive decline and Alzheimer’s. A study reported in December shows that higher levels of leptin are associated with decreased risk for cognitive decline. Leptin levels are positively associated with sleep: when you get enough, your body’s leptin levels are higher.

Leptin is an important regulatory hormone implicated in appetite and weight gain. It also has activity in the CA1 region of the hippocampus, an area of the brain this is critical for learning and memory. Weight loss in late life is associated with cognitive decline (see this post about frailty, a syndrome of weight loss and other forms of decline), so researchers thought that leptin might be involved. Even though higher levels of leptin are related to weight loss, patients with cognitive problems actually had lower levels of leptin.

The researchers looked at the relation of leptin and risk for Alzheimer’s disease, and between leptin and brain volume (how much brain tissue each person had). The results showed that people with higher levels of leptin were less likely to develop Alzheimer’s. And those with the highest levels of leptin had the largest brain volumes.

People who sleep less have been found to have lower levels of leptin. In fact, this may be a cause of increased weight in people with sleep problems. Being overweight in middle age is related to an increased risk for cognitive decline in later life. So it appears that there may be a complex relation between sleep, weight, and cognitive function.

Once again, getting enough sleep and maintaining a health body weight may be keys to long-term brain fitness.

Reference:

Lieb W et al. (2009)  Association of plasma leptin levels with incident Alzheimer disease and MRI measures of brain aging.  JAMA, 32, 2565-2572.