C ARBOHYDRATES AND S EASONAL A FFECTIVE D ISORDER

13.3.2 C ARBOHYDRATES AND S EASONAL A FFECTIVE D ISORDER

Seasonal affective disorder (SAD) is defined as a “condition characterized by recur- rent depressive episodes.” 64 The initial description of this disorder revealed that the

depressive episodes occurred in the winter, with the depressive symptoms beginning in the fall and continuing throughout the winter months. As spring approaches, the depressive symptoms begin to remit and the individual with this disorder is symptom- free during the summer months.

Awareness of the fact that some individuals have seasonal depression has existed for centuries. Hippocrates 65 recorded the existence of seasonal depressions, and eight centuries later, Posidonius observed that “melancholy occurs in Autumn, whereas Mania in Summer” (cited in Roccatagliata 66 ). While there was continued awareness of the existence of a seasonal depression and Greco-Roman physicians even treated it with sunlight, seasonal depressions were not systematically described or investi- gated until the 1980s. Interest in seasonal depression was stimulated by the report of an engineer who documented his own seasonal mood swings for 15 years. He

even postulated that light may have an influence on his mood state. 67 The initial investigation, conducted by Rosenthal and his colleagues, consisted of several pilot

studies designed to document the validity of a seasonal variation in depression. One of the studies focused on a woman who consistently developed depression every winter since she was an adolescent. When she moved north, her depression started earlier in the fall, was more severe, and persisted longer into the spring. On several occasions she took a winter vacation to Jamaica, and within 2 days she experienced

a complete elimination of her depression. She was treated with light therapy, the current standard treatment for SAD, early in the morning to determine whether exposure to a full spectrum of light would ameliorate her symptoms. This pilot study and others 64,68 led to the classification of SAD as a psychiatric disorder.

SAD is characterized by many of the typical symptoms of depression, including dysphoria, concentration difficulties, a decline in energy, irritability, anxiety,

decreased libido, social withdrawal, and being overrepresented by the female gen- der. 67,69,70 Some individuals believe that patients with SAD differ from classically depressed individuals in that they experience increased fatigue, sleep duration, appe-

tite, and weight gain. 67 However, others have found a difference only in sleep duration and carbohydrate cravings 69 or carbohydrate cravings and increased appetite. 70 These studies reveal that the symptom most consistently identified as distinguishing SAD from other depressive disorders is carbohydrate cravings. This is a symptom that

has been identified in 60 to 88% of individuals with SAD (see Takahashi et al. 71 for

a review). However, there is some evidence that the carbohydrate cravings are more prevalent in females than in males. 71 Also, most of the studies investigating SAD are conducted on females, probably because this is the group that is most affected by this disorder. Consequently, most of what we know about SAD is from investi- gations with a predominantly female population.

Dietary Carbohydrates as Mood and Performance Modulators

Also, most of the research has been conducted on individuals with winter depression. However, not all individuals with SAD have winter depression. Some have a summer depression and experience an amelioration in their depression during the winter months. 72,73 This is an important distinction, because these two groups of individuals seem to exhibit a different set of symptoms. The individuals with winter SAD most frequently exhibit carbohydrate cravings and an increase in appetite with an accompanying increase in food consumption and weight gain. 72–74 However, individuals with summer SAD are less likely to report carbohydrate cravings and more likely to report an appetite decrease and weight loss. 72,73 These are important differences, suggesting that there may be two distinct groups of SAD patients. Most of what we know relates to individuals with winter SAD, in terms of both treatment and characteristics, as most studies have focused on winter SAD. This may be because the prevalence of winter depression seems to be much greater than summer

depression. Rosen et al. 75 revealed that the prevalence rates for winter depression in three northeastern cities ranged from 4.7 to 9.7%, whereas that for a southern city was 1.4%. The corresponding rates for summer depression ranged from 0.5 to 3.1% for three northeastern cities and was 1.2% for a southern city. It is therefore important to keep this point in mind, because the information presented seems to be most applicable to individuals with winter SAD.

The carbohydrate cravings that have been identified as the most distinguishing characteristic of individuals with winter SAD are correlated with an increase in

appetite and food consumption. 74 Not only are these variables correlated, but it has been demonstrated that SAD patients retrospectively report changes in food con- sumption with the seasons of the year. 76 Meal consumption during the summer was less than during any other season, and carbohydrate consumption was the least during the summer and the greatest during the winter months. This increase in the con- sumption of carbohydrates came primarily from sweet snack foods consumed in the

afternoon and evening. 77 About 85% of the total snack carbohydrate consumption came from sweet foods such as cakes. The increased consumption of total carbohy- drates, including both starch and sweet foods, declined during the second half of the day with therapy and as the SAD patients’ depression ameliorated.

The studies conducted with SAD patients clearly demonstrate that they increase their cravings for and consumption of carbohydrates, especially sweet snack foods, during the afternoon and evening as the winter months approach and as they become depressed. As the summer months approach or with therapy, these patients show a reduction of both carbohydrate cravings and intake. Anecdotally, some of these patients report that they eat the carbohydrates to energize themselves or to perk up. 64 This is consistent with the evidence documenting that SAD patients state not only that they ingest carbohydrates in response to a variety of symptoms of depression,

but also that they do so to alleviate these symptoms. 78 Individuals with SAD therefore may be using carbohydrates to combat their feelings of depression and the anergy that accompanies it.

The use of carbohydrates to combat some of the symptoms of depression has been experimentally demonstrated by Rosenthal and his colleagues. 79 These inves- tigators compared the mood-altering effect of a carbohydrate-rich and protein-rich meals on 16 patients with a diagnosis of SAD and 16 matched control individuals.

Functional Food Carbohydrates

This study revealed that following consumption of the carbohydrate-rich meal, the SAD patients demonstrated a slight decrease in fatigue and a temporary decline in vigor. The normal controls, however, experienced an increase in fatigue and a continued decline in vigor for 3 h after meal consumption. Following a protein-rich meal, both SAD and normal controls experienced an increase in fatigue and a decline in vigor. This study has demonstrated that a carbohydrate-rich meal affects SAD patients differently than normal controls and provides some suggestive evidence that these individuals may be using carbohydrates to combat the anergy they may be feeling. However, this is only one study, so the results must be viewed as tentative until further evidence confirms the mood-altering effect of carbohydrate consump- tion. Given that SAD patients have cravings for sweet carbohydrate-rich snacks, consume more of these snacks when depressed, and report that they feel better when consuming them, as well as the suggestive experimental evidence from the Rosenthal

et al. 79 study, the hypothesis that these individuals are consuming sweet carbohy- drate-rich snacks to self-medicate seems to have some validity.