Course:RSOT513/2010W2/mood disorder

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Seasonal Affective Disorder (SAD)

The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) defines seasonal affective disorder (SAD) as a “seasonal pattern of recurrent major depressive episodes during the fall/winter in the absence of seasonal psychosocial stressors, with full remission of symptoms in spring/summer”.[1]pp636


The cause of seasonal affective disorder (SAD) remains unknown, but researchers have identified multiple hypotheses.[2] The major hypotheses include circadian rhythms, neurotransmitter function, and genetics.[1][2]

Circadian Rhythms

Light is the most powerful external time cue for the internal circadian pacemaker.[1] Therefore light can shift circadian rhythms in the human body.[1] Circadian rhythm hypotheses include photoperiod, phase shift, and more recently, disturbances in thermoregulation and electroencephalographic slow-wave sleep.[1] However, the photoperiod and phase shift hypotheses are more prominent.[1]

Phase shift hypothesis

The phase shift hypothesis is the most popular circadian rhythm hypothesis.[2] According to this hypothesis, SAD is caused by a phase delay of internal circadian rhythms in relation to external cues.[1][2] Evidence to support this theory includes the correction of phase delay in some patients with SAD with properly timed bright light and melatonin administration.[1]

Photoperiod hypothesis

The photoperiod hypothesis proposes that SAD is a result of the shorter light/dark cycle of winter.[1] Research to prove this hypothesis has focused on the correlation between the prevalence of SAD with higher latitudes, the duration of melatonin secretion in individuals with SAD, and how light therapy works in the treatment of SAD.[1] Studies suggest a correlation between SAD and higher latitudes due to shorter winter days and longer nights.[1] Melatonin is a hormone that is only secreted at night and shuts off in the morning, working as a signal for the light/dark cycle in many mammalian circadian systems.[1] Patients with SAD have a longer duration of melatonin secretion during the winter when compared to summer.[1] The third line of research is the mechanism of light therapy and whether the extension of the light/dark cycle with artificial light is needed to treat SAD. The thought is that a longer light/dark cycle reduces the duration of melatonin secretion.[1][3]

Neurotransmitter function

Neurotransmitters of most interest are serotonin and dopamine.[1][3] Evidence shows that seasonal differences in serotonin levels exist in healthy individuals.[1][3] Serotonin controls biological functions such as eating and sleeping, and evidence has shown the possibility of dysfunction with serotonin receptors in people with SAD.[1][3] Carbohydrate rich meals have been observed to increase brain serotonin levels which may explain the reported cravings.[3]

Dopamine is another neurotransmitter involved in SAD and a dysfunction in the dopamine system may be responsible for some SAD symptoms because dopamine is responsible for pleasure and social interaction.[3] Prescription of antidepressants that act on the dopamine system can prevent the symptoms of SAD.[3]


Twenty-five percent to 67% of individuals with SAD have a family history of an affective disorder, with 13% to 17% of these individuals having a first degree relative with SAD.[1] Researchers have identified two genes related to the serotonin system that is associated with SAD.[1][3] Circadian clock genes are also of interest because of the importance of circadian rhythm hypotheses in the etiology of SAD.[1] Animal studies have also shown that mutations in the clock genes cause altered circadian rhythms.[1]


The prevalence of SAD is 0.4% in the United States and 1.7% to 2.9% in Canada.[2] Summer cases of SAD constitute about 1% of all cases.[4] The prevalence of SAD is higher in more northerly areas given the shorter winter days.[2][5] In the United States, SAD prevalence increases with latitude from 1.4% in Florida to 9.9% in Alaska.[6] In addition to living in higher latitudes, those who are deprived from natural light such as "shift workers and urban dwellers, who experience reduced levels of exposure to daylight in their work environments” may experience a higher prevalence of SAD.[7]

According to population surveys, SAD affects females and males at a ratio of 2:1.[6] The mean age of SAD onset is 27.2 years.[6] SAD can occur in children and adolescents as well, with symptoms initially noticed by teachers or parents.[4]

Common Signs and Symptoms

The DSM-IV categorizes SAD as a subtype of major depression with a specific time pattern.[5] In the DSM-IV, SAD is “conceptualized as a seasonal pattern of recurrent major depressive episodes during the fall/winter in the absence of seasonal psychosocial stressors, with full remission of symptoms in spring/summer”.[1]pp635 In addition to the seasonality of SAD, two other characteristics include atypical depressive symptoms and responsiveness to light therapy.[1]

Common symptoms include:[2][7]

  • Reduced pleasure or interest
  • Psychomotor agitation or retardation
  • Loss of energy
  • Feelings of worthlessness or excessive inappropriate guilt
  • Reduced ability to think or concentrate
  • Indecisiveness
  • Recurrent thoughts of death
  • Pain
  • Fatigue
  • Hypersomnolence (excessive sleeping)
  • Increased appetite and eating
  • Carbohydrate cravings
  • Weight gain
  • Avoidance of social situations
  • Hopelessness

It is important to note that those with SAD may not experience every symptom.[7]

A rare form of SAD includes symptoms during the summer of:[4][7]

  • Poor appetite
  • Weight loss
  • Trouble sleeping
  • Agitation
  • Anxiety

In even fewer cases, some may experience winter and summer depression with remission during the fall and spring near the time of the equinoxes.[4]

Diagnostic Criteria

The DSM-IV criteria for diagnosis of SAD[8] are:

  • The onset of major depressive episodes at a particular time of the year
  • Full remission at a characteristic time of the year
  • Two major depressive episodes in the last two years showing a temporal relationship
  • Seasonal episodes outnumbering non-seasonal depressive episodes

Differential Diagnoses

SAD can be difficult to diagnose as many of the symptoms are similar to those of bipolar disorder and other types of depression.[9] Further, the physical symptoms of thyroid disorder can be similar to depression.[9] Thus it is important to rule out hypothyroidism and other conditions such as phase delayed sleep and anniversary grief reactions when diagnosing SAD.[2] Diagnosis of SAD will need to rule out other conditions with seasonal patterns such as bulimia nervosa, premenstrual depressive disorder, obsessive-compulsive disorder (OCD), panic disorder, post-traumatic stress disorder (PTSD) and attention deficit hyperactivity disorder (ADHD).[2] Some patients with alcoholism may manifest a pattern of seasonal alcohol-induced depression.[9] Other diagnoses with similar mechanisms include general anxiety disorder, late luteal phase dysphoric disorder, and chronic fatigue syndrome.[9]

Implications for Occupations

The symptoms of SAD impact participation in daily activities for individuals with SAD.[1][3] Occupation is everything that a person does to occupy oneself: looking after oneself, enjoying life through leisure, and contributing to society, otherwise known as productivity.[10]


A recent study found that people with SAD have lower sleep efficiency.[11] They generally sleep more than others but do not feel refreshed upon awakening.[3] This can explain why getting out of bed in the morning can often be difficult for individuals with SAD.[3] People with SAD also report increased food consumption and changes in food preference from light meals to high-carbohydrate meals.[3]

Potential Occupational Performance Issues

  • Difficulty getting out of bed in the morning related to changes in sleep patterns[3]
  • Decreased performance in routine chores (e.g. shopping or cooking a meal)
  • Difficulty with weight management related to carbohydrate cravings and hyperphagia in response to deficiency in brain serotonin transmission and/or over secretion of insulin
  • Engagement in adverse health-risk behaviours (e.g. alcohol and tobacco use)


Most individuals with winter SAD experience disability at work and in their social relations.[12] Studies on common mental disorders, including depressive disorders, have reported on decreased quantity and quality of work output, work role limitations, and increased effort needed to remain productive.[13] In severe cases, people with SAD have taken time off work or stopped work altogether.[3] Tasks involving logic are noted to be particularly difficult.[3] Apart from interfering with work performance, daytime tiredness and fatigue can be a public safety concern as such symptoms can affect driving performance.[14]

Potential Occupational Performance Issues

  • Diminished ability to manage demands at work related to decreased capacity to process information and concentrate[3]
  • Increased interpersonal difficulties in the workplace[3] related to fatigue
  • Reduced driving ability related to difficulty estimating distances[3]
  • Uncertainty regarding career choice [In a conversation with S. Hale, OT (March 2011)]
  • Difficulty managing household tasks [In a conversation with S. Hale, OT (March 2011)]


Leisure activity limitations in social and occupational roles are common among people experiencing depressive symptoms.[15] Social functioning is defined as “an individual's interactions with their environment and the ability to fulfill their role within such environments as work, social activities, and relationships with partners and family."[16]pp63 Socializing requires expending the energy involved in social contact, which may be difficult for those experiencing a profound lack of energy.[3] Individuals with SAD may experience social interaction as an overwhelming demand and thus may choose to avoid social contact.[3] This lack of desire to socialize along with decreased energy, interest, and motivation may impact participation in leisure and physical activity. There is an association between depression level and leisure activity level.[15] Depressive symptoms may impact participation in leisure activities for males more so than for females.[15]

Potential Occupational Performance Issues

  • Decreased social contact related to wanting to be left alone[3]
  • Difficulty maintaining relationships related to social withdrawal
  • Difficulty maintaining intimacy related to decreased sex drive: “Many people report not wanting to be touched or to exert themselves in any way”pp39

Role of Occupational Therapy in Treating SAD

Given that SAD impacts a wide variety of occupational performance areas in a person’s life as described in the aforementioned section, occupational therapists (OTs) play a key role in helping individuals cope with SAD. OTs incorporate best practices and principles from various health care disciplines into their therapeutic practice with clients with SAD, including assessment, treatment, and evaluation. Care and treatment are holistic and tailored to the client’s identified goals, needs, and responsiveness to treatments. In addition to educating clients on the etiology, prevalence, symptoms and occupational performance issues associated with SAD, OTs play a large role in treating patients or educating them on the different types of interventions available. Of particular importance is educating clients on fatigue management and energy conservation, as low energy level is commonly reported in people with SAD.[3] With increased energy levels, clients can hopefully return to doing activities that they need and want to do with respect to self-care, productivity, and leisure. The two main treatment approaches that OTs come across are the biomedical approach and the psychosocial approach.

Biomedical approaches

OTs can play a large role in educating their clients on biomedical interventions, which can be very effective in minimizing symptoms that impact occupational performance issues in the areas of leisure, productivity and self-care. OTs should be knowledgeable about the most commonly used biomedical treatment approaches, which are light therapy and pharmacotherapy, to address SAD.

Light Therapy

Bright light therapy, or phototherapy, has been used for over 20 years to treat SAD[17] with numerous studies citing its effectiveness.[18][19] Light therapy is recommended as a first-line treatment for SAD in Canadian, American, and international clinical guidelines.[19] The mood of individuals with SAD can improve with as little as 20 minutes of bright light exposure.[20] Bright light is more effective than dim light in protecting against “mood lowering” which commonly occurs in SAD.[20][21]p2

Light boxes are widely available devices which typically provide fluorescent light as a treatment for SAD.[17] OTs should be familiar with typical usage guidelines provided to users of light boxes and emphasize to clients the need for clinical monitoring to ensure the appropriate doses of light.[17] Effective doses of light therapy vary depending on the individual. Studies have shown effective doses ranging between 3,000 lux 2 hours/day for 5 weeks[22] to 10,000 lux 30 minutes/day for 8 weeks.[19] Patients are typically advised to sit “within several yards” of the device and glance occasionally (rather than stare) at it.[23]p20 Commercial light boxes are not regulated by U.S. law and, as such, OTs should recommend medical consultation and advise caution when selecting and using them.[17][23] Only 41% of SAD patients comply with clinical practice guidelines and use light therapy regularly due to reasons of inconvenience and ineffectiveness.[24] As such, OTs can help clients develop methods for incorporating light therapy effectively into their daily routines and complying with clinical guidelines.[25]


Light therapy does not work for everyone. Twenty to 50% of those diagnosed with SAD do not gain adequate relief from it.[26] In addition to the lack of efficacy, the required time commitment and the tendency for recurrence are additional reasons why individuals with SAD explore alternative treatments to light therapy.[27] In a study comparing the effectiveness of light therapy and an antidepressant medication, fluoxetine, evidence was found to support the effectiveness and tolerability of both treatments for SAD.[19]

Antidepressant Medications (Pharmacotherapy)

Antidepressant medication (ADM) has been shown to be effective in treating various forms of depression.[28] Of the various types of ADMs used to treat SAD, selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine and sertraline appear to be most effective.[29][2] OTs play a role in helping their clients understand how such medications, if prescribed, can decrease acute symptoms and lead to enhanced engagement in daily occupations. ADMs are considered to be largely compensatory in nature.[28] In other words, ADMs may suppress depressive symptoms while they are being used, but lasting changes are not guaranteed once treatment is discontinued. A growing body of evidence is showing that psychosocial approaches to therapy, such as cognitive and behavioural interventions, may have more enduring effects than biomedical interventions.[28]

Psychosocial approaches to SAD interventions

OTs play an important role in the implementation and recommendation of psychotherapeutic interventions, which follow psychosocial rehabilitation and recovery-based approaches. The roles of OTs in psychosocial rehabilitation often include the following:

  • Identifying the clients' psychosocial issues, strengths and limitations associated with the condition
  • Assessing clients’ readiness, motivation, and belief in their abilities to make changes in their lives
  • Identifying what is meaningful to the client
  • Identifying social support systems that are available to help the client achieve their goals.[30]

OTs often use guiding frameworks, such as the Canadian Model of Occupational Performance[31] and the Model of Human Occupation[32] to help clients set rehabilitation goals and identify areas of occupational performance that are affected by the symptoms associated with SAD. Several types of interventions fall within the psychosocial scope of occupational therapy, and are used by an interdisciplinary team of health care providers who work with clients with SAD. In a health care system that is driven largely by medical models, OTs can play an important role in promoting psychosocial rehabilitation and recovery when addressing the underlying issues associated with SAD.[33] OTs use clinical reasoning to draw holistically upon principles of a variety of treatment approaches when implementing individual and group therapy among clients with SAD.

Group Therapy

OTs in mental health settings often lead groups for inpatients and outpatients with mood disorders.[34] Some group therapy topics that target occupational performance issues related to SAD could include:

  • Stress management
  • Weight control and nutrition
  • Smoking cessation
  • Substance abuse
  • Time management
  • Social skills and networking
  • Wintertime activities
  • Sleep education
  • Self-esteem
  • Sexual health

These group therapy sessions are often guided by a number of different theoretical and therapeutic frames of references, which use methods that are shown by research to be effective. Cognitive Behavioural Therapy, Mindfulness-Based Cognitive Therapy, Behavioural Activation, Problem-Solving Therapy, Positive Psychotherapy, Self-System Therapy and Outdoor Therapy are just some of the more common approaches that OTs use when framing their interventions for client with SAD.

Cognitive Behavioural Therapy

Cognitive Behavioural Therapy (CBT) is used widely by OTs to treat SAD and other mood disorders. Originally developed by Beck and colleagues,[35] CBT aims to help clients identify the expectations and interpretations that can lead them towards depression and anxiety; adjust to reality; and break through their avoidances and inhibitions.[36] When implemented appropriately, it can help people change their cognitive processes, which may then correspond with changes in their feelings and behaviours.[37] CBT for SAD focuses on the early identification of negative anticipatory thoughts and behavior changes associated with the winter season, and helps clients develop coping skills to address these changes.[38]

By adopting a CBT approach, OTs can help clients with SAD engage in pleasurable activities in the winter months (i.e. behavioral activation) and help people think more positively (i.e. cognitive restructuring).[38] If qualified, OTs can deliver CBT skills training groups to SAD patients. The skills that OTs teach can have a direct impact on occupational performance issues and can include:[38]

  • developing a repertoire of wintertime leisure interests
  • using diaries to record automatic negative thoughts
  • creating a balanced activity level
  • improving time management skills
  • problem solving about situations that initiate negative thinking
  • setting goals and plans for maintaining gains and preventing relapse

CBT, or a combination of CBT and LT, can lead to a significant decrease in levels of depression amongst those with SAD.[27][25] With non-seasonal depression, CBT appears to be about as effective as ADM in terms of acute distress reduction; however, the effects of CBT are shown to be longer lasting than ADM.[28][39] There have been no direct comparisons made between CBT and ADM specifically for SAD.[38] CBT is effective in treating both mild and more severely depressed patients, and is shown to prevent or delay the relapse of depressive symptoms better than other treatments for depression.[38][40] There are no known adverse physical side effects of CBT.[38]

Mindfulness-based cognitive therapy (MBCT)

Mindfulness-based cognitive therapy (MBCT) is an intervention that aims to increase meta-cognitive awareness to the negative thoughts and feelings associated with relapses of major depression.[41] Unlike CBT, MBCT does not emphasize changing thought contents or core beliefs related to depression. It instead focuses on meta-cognitive awareness techniques, which are said to change the relationship between one’s thoughts and feelings.[42] The act of passively and repetitively focusing one’s attention on the symptoms, meanings, causes, and consequences of the negative emotional state of depression is called rumination.[43] MBCT aims to reduce rumination by addressing the cognitive patterns associated with negative thinking and cultivating mindfulness through meditation and self-awareness exercises.[44] Once awareness of feelings and thoughts are cultivated, MBCT emphasizes accepting and letting them go.[44] OTs can train clients with SAD in MBCT skills, which often takes place in a group setting over a number of weeks. Training focuses on the concept of “decentering,” which is the act of taking a present-focused and non-judgmental stance towards thoughts and feelings.[44] By learning how to decenter, a person can distance themselves from the negative thoughts and feelings that may affect occupational performance in areas such as eating healthily, maintaining social relationships and being productive at work. By bringing attention back to the present (e.g. by focusing on their breath), clients gradually begin to observe their thought processes rather than reacting to them, thus, facilitating occupational engagement.

Behavioural activation

Behavioural activation (BA) is considered to be a traditional form of psychotherapy.[45] It is based on activity scheduling and aims to increase the number of positively reinforcing experiences in a person’s life. BA has shown comparable efficacy with other psychosocial therapies such as CBT, as well as with ADM treatment among mildly to moderately depressed patients.[46] BA has the potential to be very effective when used in occupational therapy, as it focuses on occupying one’s time with activities and experiences that are meaningful, positive, and engaging to the client. As such, clients who have occupational performance issues in productivity, leisure, and self-care may benefit from such therapy.

Problem-solving therapies

This intervention involves the patient creating a list of problems, identifying possible solutions, choosing the best solutions, creating a plan to implement them, and evaluating outcomes with respect to the problem. Further studies are needed to better understand the conditions under which problem-solving therapy is effective for depression;[47] however, this type of therapy is compatible with occupational therapy approaches to SAD. The Canadian Occupational Performance Measure (COPM)[48] is a widely-used instrument that supports clients working with OTs in identifying their occupational needs, setting goals, and assessing change in occupational performance. Similar to the use of the COPM, OTs can use problem-solving therapy to focus on client choice and empowerment - principles that are fundamental to psychosocial rehabilitation and recovery.[49]

Positive psychotherapy

Positive psychotherapy (PPT) works to increase positive emotions in depressed clients and enhance engagement and meaning in activities that take place in a person’s life. Seligman and colleagues[50] found that group PPT was effective in treating mild to moderate depression for up to one year after the treatment was terminated. They also found that individual PPT led to greater remission rates than non-PPT treatments plus pharmacotherapy. OTs could adopt a PPT approach when conducting individual and group therapy sessions with clients with SAD. For example, they could introduce activities that instill success and learning, identify clients' interests, and encourage clients to engage in positive and personally meaningful occupations.

Self-System Therapy

Self-System Therapy (SST) is based on the notion that depression arises from chronic failure to attain personal goals due to one’s inability to self-motivate and pursue their goals.[51] SST is designed to improve one's ability to self-regulate and attain personal goals by helping define goals, identify the steps needed to attain them, identify the barriers that are preventing progress, and create a plan for how the goals may be achieved. This intervention draws upon techniques from cognitive therapy and BA, but has an overall emphasis on self-regulation. OTs can play a large role in helping SAD clients set and attain goals related to self-care, productivity, and leisure.

Outdoor therapy

Outdoor therapy is yet another psychotherapeutic intervention that OTs can recommend. Outdoor work has been used effectively as a therapy to treat those with mood difficulties during the winter season in Denmark.[52] As an example, horticulture groups have shown positive impacts on depressive symptoms, which can be associated with psychosocial adaptation leading to healthy occupational performance.[53] Similarly, outdoor walking can provide a “therapeutic effect” to individuals with SAD that is on par with light therapy.[54] OTs should incorporate outdoor occupations into their interventions with clients diagnosed with SAD.

Assessments for SAD

OTs also play a role in assessing and providing ongoing evaluation of clients who have SAD or who are suspected to have SAD. Assessments are most often used to determine if a particular treatment is working and what aspects of the disorder require the most attention. Two commonly used assessments for SAD are the Structured Interview Guide for the Hamilton Rating Scale for Depression – Seasonal Affective Disorder version (SIGH-SAD)[55] and the Beck Depression Inventory, 2nd edition (BDI-II).[56] The SIGH-SAD is a semi-structured interview that includes 21 non-seasonal depression items and an extra 8-item SAD-specific subscale. The BDI-II is quicker to administer and contains 21 measures of depressive symptom severity, which also captures atypical symptoms that are common in SAD.


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