(HealthDay News) — For older adults, more galanin-immunoreactive intermediate nucleus neurons are associated with less fragmented sleep, according to a study published online August 20 in Brain.

Noting that in rodents, lesions of the hypothalamic ventrolateral preoptic nucleus cause fragmented sleep, Andrew S.P. Lim, MD, from the University of Toronto, and colleagues examined whether intermediate nucleus cell loss contributes to fragmentation and loss of sleep. Data were collected for 45 older adults (12 with Alzheimer’s disease) who had at least one week of wrist actigraphy proximate to death. Immunohistochemistry and stereology were used upon death (median of 15.5 months later) to quantify the number of galanin-immunoreactive intermediate nucleus neurons in each individual.

The researchers found that individuals with versus those without Alzheimer’s disease had fewer galaninergic intermediate nucleus neurons (P=0.001). After adjustment for age and sex, having more galanin-immunoreactive intermediate nucleus neurons correlated with less fragmented sleep; this correlation was stronger for those with a lag between actigraphy and death of less than one year (P=0.023). This correlation was similar for those with and without Alzheimer’s disease. There were no similar associations for two other cell populations near the intermediate nucleus.

“These data are consistent with the intermediate nucleus being the human homologue of the ventrolateral preoptic nucleus,” the authors write.

Full Text (subscription or payment may be required)