Heterogeneity has been identified in cases of SAD during both depressed and non-depressed periods. It has been suggested that discriminant analysis of symptoms may differentiate between types of patients with SAD.

Dr Namni Goel and colleagues from Columbia University in New York investigated 165 depressed individuals with SAD to determine whether different clinical profiles could differentiate between patients.

Patients with bipolar affective disorder (type I or II) or major depressive disorder (MDD), both with seasonal variation, were included in the study, which involved assessment using the Structure Interview Guide for the Hamilton Depression Rating Scale – SAD version (SIGH-SAD).

Patients were categorised on the basis of bipolar or unipolar diagnosis, non-depressed mood state, sex, race, menstrual status, eye colour, marital and employment status.

The researchers found that bipolar patients had higher SIGH-SAD scores generally, indicating greater severity of depression, and also had more psychomotor agitation and social withdrawal compared to individuals with MDD. Bipolar I patients had more severe psychomotor retardation, social withdrawal and late insomnia than type II patients.

Differentiation was also possible between men and women with SAD, with men showing more obsessive and compulsive symptoms and suicidality, and women more weight gain and early insomnia.

Black patients were more likely to show hypochondriasis and social withdrawal while whites had more guilt and fatiguability. Those with dark eyes were more likely to be depressed and fatigued, while single patients had more hypochondriasis and diurnal variation.

Atypical symptoms were more common among employed individuals than those who were not working. In most cases, distinguishing items were included in the Hamilton Depression Rating Scale.

The researchers conclude that the patients’ characteristics described here may be used to differentiate subgroups of patients with SAD. They add that the findings could be used to provide additional support for at-risk groups in the community.

Source: Depression and Anxiety 2002

© Health Media Ltd 2002
http://www.health-news.co.uk