This is the first study examining SERT uptake in patients with NES. The impetus for this investigation was the efficacy of the SSRI, sertraline, in the treatment of NES in three clinical trials (O’Reardon et al., 2004
; O’Reardon et al., 2006
; Stunkard et al., 2006
). This efficacy suggests that the serotonin system is involved in the pathophysiology of this syndrome.
The current study showed that night eaters, compared to controls, had significantly greater midbrain SERT binding, with a large effect size of 0.77. Left and right temporal lobe differences were noted, but did not reach statistical significance, possibly due to the small sample size.
How is increased SERT binding related to the response of NES to sertraline? These findings may reflect a syndrome-specific increase in SERT that results in an overall decrease of serotonin within the synapse. Thus, sertraline may act by blocking the homeostasis.
It is intriguing that SERT availability among night eaters is different from that which has been found for persons with bulimia nervosa (Tauscher et al., 2001
) and binge eating disorder (Kuikka et al., 2001
). These findings may reflect differences in eating pathology manifested by the binge eating behavior of persons with bulimia nervosa and binge eating disorder versus the appropriately portioned, but circadian-delayed eating behavior of night eaters (Allison et al, 2005
NES appears to have little in common with the few psychiatric conditions with elevated SERT binding: chronic cocaine dependence, one study of obsessive compulsive disorder, and bipolar II disorder. Night eaters are more likely to have a history of substance abuse and dependence than non-night eaters (Lundgren et al., 2006
), although this is not specific to cocaine use. No studies to date have linked night eating behavior to obsessive compulsive disorder or mania.
The main limitation of this report is the small sample size which may have impacted the statistical power necessary to detect differences in the temporal lobes. The pilot nature of this study required this limitation, but does not negate the importance of these findings. Future studies should expand the study of SERT binding in night eaters to determine if levels of SERT binding can predict SSRI treatment response. SERT availability should also be examined in subgroups of night eaters (e.g., depressed versus non-depressed, early versus late onset, and familial versus non-familial) to determine if difference in SERT binding are a function of additional variables.