Declarative Memory Impairment and Emotional Bias in Recurrent Depression with a Seasonal Pattern: The Interplay between Emotion and Cognition in Seasonal Affective Disorder

Abstract

Seasonal Affective Disorder (SAD) is a subtype of Major Depressive Disorder (MDD) with a seasonal pattern. Although it is a pathological condition limited to specific seasons of the year, during the symptomatic period, patients may experience a significant impairment of well-being and daily quality of life as a result of the depressed mood, associated with other symptoms defined as atypical of MDD. While extensive evidence of memory deficits has been found in MDD, explicit memory impairments in SAD are insufficiently studied. This study aims to investigate the cognitive processing of emotional stimuli in women with SAD, in particular the interplay between emotions and declarative memory. One hundred and twenty young women, screened from an initial number of 1125 university students, were divided into two groups, an experimental one that included 60 medically untreated women affected by “winter type SAD” and a control group of 60 non-SAD women. Different subjects were randomly submitted to two types of audio−visual stories, neutral or arousal, and then their memory performances were analyzed by means of a free-recall test and a recognition memory test. In both the free-recall test (p < 0.008) and in the recognition memory test (p < 0.002), the SAD group showed impaired memory performances. Taken together, our novel key findings suggest that SAD is characterized by impairment in declarative memory and attentional bias for emotional negative stimuli.

Keywords: cognition; declarative memory; depression; emotion; seasonal affective disorder; seasonality.

Figure 1

Sampling flow chart.

Figure 2

Emotional rating. Mean (±SEM) ratings of the emotional reaction to the neutral and arousal stories in the SAD and control groups. * p < 0.01; ** p < 0.001.

Figure 3

Free recall scores. (a) Score (mean ± SEM) of the total story recall of the participants under neutral and arousal conditions. * p < 0.01; ** p < 0.001. (b) Recall scores (mean ± SEM) for each phase of the story, in subjects assigned to the arousal condition. * p < 0.05; ** p < 0.001.

Figure 4

Recognition memory score. (a) Total score (mean ± SEM) of the questionnaire of the subjects assigned to the neutral and arousal conditions. * p < 0.01; ** p < 0.001. (b) Questionnaire scores (mean ± SEM) for each phase of the story of the subjects assigned to the arousal condition. * p < 0.05; ** p < 0.001.

Figure 5

Correlation between GSS scores and free-recall and recognition memory scores in the SAD group. A negative relationship is shown both in the free-recall test and in the recognition memory test (questionnaire).