Seasonal mood change and neuroticism: the same construct?

The personality trait of neuroticism has been found to be associated with a polymorphism in the regulatory region of the serotonin (5-HT) transporter gene (5-HTTLPR). This same genetic polymorphism has also been associated with seasonal changes in mood and behavior, or seasonality. The purpose of the current study was to determine whether seasonality and neuroticism are actually the same construct given that they are both associated with the same genetic polymorphism. We administered the Seasonal Pattern Assessment Questionnaire (SPAQ), which measures the severity of seasonality, and the Revised NEO Personality Inventory (NEO-PI-R), which measures the severity of neuroticism, to 45 subjects diagnosed with seasonal affective disorder (SAD). SAD is a clinical expression of seasonality in which patients develop a major depressive disorder in the winter that remits in the summer and can be treated with light therapy. No significant correlation was found between neuroticism and seasonality. We conclude that seasonality and neuroticism are not the same construct, even though the 5-HTTLPR polymorphism is a genetic risk factor for each.

Greater improvement in summer than with light treatment in winter in patients with seasonal affective disorder

OBJECTIVE

The authors sought to compare the degree of mood improvement after light treatment with mood improvement in the subsequent summer in patients with seasonal affective disorder.

METHOD

By using the Seasonal Affective Disorder Version of the Hamilton Depression Rating Scale, the authors rated 15 patients with seasonal affective disorder on three occasions: during winter when the patients were depressed, during winter following 2 weeks of light therapy, and during the following summer. They compared the three conditions by using Friedman's analysis of variance and the Wilcoxon signed ranks test.

RESULTS

The patients' scores on the depression scale were significantly higher after 2 weeks of light therapy in winter than during the following summer.

CONCLUSIONS

Light treatment for 2 weeks in winter is only partially effective when compared to summer. Further studies will be necessary to assess if summer's light or other factors are the main contributors to this difference.

Role of serotonin transporter promoter repeat length polymorphism (5-HTTLPR) in seasonality and seasonal affective disorder

Seasonal variations in mood and behavior (seasonality) and seasonal affective disorder (SAD) have been attributed to seasonal fluctuations in brain serotonin (5-HT). the short (s), as opposed to the long (l), allele of the 5-HT transporter linked polymorphism (5-HTTLPR) has been associated with neuroticism and depression. We hypothesized that this short allele would also be associated with SAD and with higher levels of seasonality. Ninety-seven SAD patients and 71 non-seasonal healthy controls with low seasonality levels were genotyped for 5-HTTLPR and compared statistically. Patients with SAD were less likely to have the l/l genotype (27.8% vs 47.9%; P < 0.01) and more likely to have the s allele (44.8% vs 32.4%; P < 0.02) as compared to controls. The three 5-HTTLPR genotypes were also differentially distributed in patients and controls (P < 0.03). The SAD patients with the l/l genotype had a lower mean seasonality score than did patients with the other two genotypes (mean +/- s.d. = 15.3 +/- 2.8 vs 17.1 +/- 3.4 respectively; P < 0.02). The 5-HTTLPR short allele contributes to the trait of seasonality and is a risk factor for SAD, providing further evidence for a relationship between genetic variation in the 5-HT transporter (5-HTT) and behavior.

Findings from the Seasonal Pattern Assessment Questionnaire in patients with eating disorders and control subjects: effects of diagnosis and location

We previously reported a high degree of seasonality as measured by the Seasonal Pattern Assessment Questionnaire (SPAQ) in 41 patients with eating disorders (ED) compared with control subjects and patients with five other affective spectrum disorders. To clarify the relationship of the specific ED diagnosis and latitude to seasonal variation in a larger sample, we administered the SPAQ to 159 women with ED as defined by DSM-III-R. Subtype diagnoses were as follows: bulimia nervosa (BN), n = 109; anorexia nervosa (AN), n = 30; BN+AN, n = 20. Patients were studied at three locations: National Institute of Mental Health (NIMH), n = 46; Medical University of South Carolina (MUSC), n = 53; University of Michigan (UM), n = 60. The control group comprised 50 female normal volunteers studied at NIMH. There was a statistically significant difference in Global Seasonality Scale (GSS) scores among the four diagnostic groups, and all ED subtypes had significantly higher GSS scores than control subjects after post hoc Bonferroni t tests. Higher GSS scores were also found in patients with BN+AN compared with patients with BN or AN alone. The patterns of change were similar to those observed in winter seasonal affective disorder (SAD). Thirteen percent of the total sample of ED patients met SPAQ criteria for winter SAD, with 2.5% each for summer SAD and subsyndromal SAD. UM BN patients (latitude 42 degrees N) had higher GSS scores and a higher prevalence of winter SAD than MUSC BN patients (latitude 33 degrees N), but this difference was not statistically significant. These data support the hypothesis that ED and SAD may involve similar pathophysiological mechanisms, possibly related to serotonin dysregulation.

Evaluation of seasonality in six clinical populations and two normal populations

The Seasonal Pattern Assessment Questionnaire (SPAQ) was used to evaluate retrospectively self-reported seasonal changes in mood and behavior (seasonality) of two normal and six clinical populations: patients with winter-seasonal affective disorder (SAD), summer-SAD, eating disorders, bipolar affective disorder, major depressive disorder and subsyndromal winter-SAD. The SPAQ successfully discriminated between groups expected to have high seasonality scores, such as winter-SAD, summer-SAD and subsyndromal winter-SAD, and normal controls. Bipolars and major depressives had normal seasonality scores. Patients with eating disorders had unexpectedly high scores. There was a general tendency for all groups to eat and sleep more and to gain weight in the winter. The implications of these findings are discussed.