seasonal affective disorder ( sad ) was first time described as syndrome of recurrent episodes of depression that occur annually ( usually in winter season at same time each year ) by rosenthal et al . in 1984 . diagnostic and statistical manual of mental disorders , 4 edition , text revision ( dsm - iv - tr ) describes sad not as a separate mood disorder but as specifier referring to the seasonal pattern of major depressive episodes that can occur within major depression or bipolar disorders . the specifier within seasonal pattern can be applied to pattern of major depressive episodes in bipolar affective disorders i , bipolar affective disorders ii and major depressive disorder ( recurrent ) . the international classification of diseases , 10th revision ( icd-10 ) gives only provisional diagnostic criteria for sad on the grounds that its status is best regarded as uncertain , and its diagnostic criteria available in research domain of icd-10 manual are three or more episodes of mood ( affective ) disorder must occur with onset within same 90-day period of year , for three or more consecutive years . remission also occurs within a particular 90-day period of the year and seasonal episodes substantially outnumber any non - seasonal episodes that may occur. although original description of sad included most people with diagnosis of bipolar affective disorder ( bpad ; most common bpad ii ) rather than recurrent major depressive disorder , who used to switch into hypomania ( or mania ) in summer season . however , subsequent research into treatment strategies for sad almost exclusively focused on it as a subtype of recurrent depressive disorder as most of clinical trials involving sad focused on either bright light therapy ( blt ) , anti - depressant drug treatments , beta - blockers , vitamins and psychotherapy . there is negligible data on role of mood stabilizers in management of sad ( winter depression ) . here , we describe response of 30 patients of recurrent major depressive disorder ( seasonal pattern  winter ) ( winter sad ) to lamotrigine , who failed to respond to different anti - depressant treatment previously . patients of sad ( winter depression ) fulfilling dsm - iv - tr criteria for major depressive disorder , recurrent , with seasonal pattern ( winter season ) , who failed to respond or responded partially to different anti - depressants were assessed from hospital records . the case records and assessment was done by different members of the resident staff , but most of them were recorded by two of the authors . they had already been assessed for mania / hypomania symptoms in current episode or in past ( particularly mania / hypomania in summer season ) using routine clinical interview and mini - international neuropsychiatric interview ( mini ) . those having history of mania or hypomania and other axis i disorders were not taken up for this study . selection criteria for this study : 
 patients having the onset of depression in autumn / winter lasting for whole of winter season and early spring.patients in whom progress was routinely monitored using hamilton depression rating scale ( ham - d).patients whose treatment was augmented with lamotrigine in addition to their routine anti - depressant medications.patients having minimum of three consecutive seasonal mood episodes.patient having a stable dose of other medications for minimum of 8 weeks and these doses were not changed during lamotrigine augmentation . 
  patients having the onset of depression in autumn / winter lasting for whole of winter season and early spring . patients in whom progress was routinely monitored using hamilton depression rating scale ( ham - d ) . patients whose treatment was augmented with lamotrigine in addition to their routine anti - depressant medications . patient having a stable dose of other medications for minimum of 8 weeks and these doses were not changed during lamotrigine augmentation . these patients had been treated with lamotrigine augmentation for their partially responding or non - responding depressive episode . they were assessed routinely at baseline , at 2 weeks , at 4 weeks and at 8 weeks of lamotrigine augmentation . more than 50% decrease in ham - d score from baseline was taken as response and a final score of less than 8 was taken as remission . lamotrigine was started at dose of 25 mg per day and gradually increased to 200 mg by 8 weeks with weekly increment of 25 mg . lamotrigine was stopped in some patients owing to development of rash . in total , 30 patients who had completed follow - up for minimum of 8 weeks were assessed for this study . mean / average and the deviations were calculated using statistical package for social sciences version 16 ( spss-16 ) . single tailed t - test was used to study the difference of means to assess the therapeutic response and pre / post analysis of change . thirty patients met the selection criteria , having a complete follow - up with fully maintained case sheets . the sample included 9 males and 21 females with a mean age of 37.14  11.31 years ( 22 to 56 years ) . before the initiation of lamotrigine , the mean ham - d score was 20.93  4.93 , suggesting an ill state of most of these patients . other variables , treatment history and treatment response are noted in table 1 . sociodemogarphic and clinical variables the mean ham - d scores with standard deviation at start of treatment at 2 weeks , at 4 weeks and , at 8 weeks are 20.93  4.93 ( range = 14 - 35 ) , 19.63  5.82 ( range = 9 - 36 ) , 11.27  5.32 ( range = 3 - 23 ) and 9.57  6.16 ( range = 2 - 23 ) , respectively . the difference in ham - d scores at 2 weeks of treatment was not significant compared to scores at baseline ( t = 0.93 , df = 58 , p = 0.177 ) . however , there was significant difference in treatment outcome as per ham - d scores at 4 weeks of treatment compared to baseline scores ( t = 7.29 , df = 58 , p < 0.01 ) and this significant difference was maintained at 8 weeks of treatment ( t = 7.88 , df = 58 , p < 0.01 ) compared to start of treatment ( zero weeks ) . an average decrease of 46.25% in ham - d score was achieved around 4 week and it was sustained to a further decrease in score by 54.27% by 8 week . the mean time for responders to achieve an approximate 50% reduction on ham - d score was 4.2  1.2weeks at a mean dose of 150 mg / day of lamotrigine . the mean dose of lamotrigine at 8 weeks was 200 mg / day with a 54.27% decline in ham - d score and 15 ( out 30 ) showed remission ( less than 8 score ) . the difference in treatment response in different age - groups , gender groups and in groups of patients with different primary anti - depressant medication was not assessed because of small study group . a few adverse effects were documented which included sedation ( seven patients ) , headache eight patients ) , fatigue ( one patient ) and benign skin rash ( one patient ) . although first descriptions of sad presented it as more prevalent condition associated with bpad , however subsequent research into its therapeutics failed to focus it as such . till now , most of the therapeutic research has failed to highlight it as bpad and there only few studies focusing on use of mood stabilizers in this condition . this retrospective , non - blinded , open - label , non - comparative study in natural settings is an attempt to highlight role of mood stabilizers in sad . this study proved significant improvement in depressive symptoms of sad patients ( winter depression ) with lamotrigine augmentation . these were the patients who had previously shown poor response to anti - depressant ( medication ) alone treatment . the role of early morning blt in winter depression may be actually an intervention based on  social rhythm therapy which has been proven as effective strategy to deal with bipolar disorder patients because early morning blt in winter depression invariably promotes concept of chronotherapeutics in management of sad . lamotrigine approved for the maintenance treatment of bpad i has also shown some efficacy for the treatment of bipolar depression . limited data is available suggesting efficacy of lamotrigine in major depressive disorder ( mdd ) ( unipolar depression ) and these studies do not support lamotrigine use in unipolar depression robustly . in view of above findings and results of our study , the nosology and therapeutics of winter depression ( and other forms of depression not responding adequately to anti - depressant treatment ) needs to be reviewed as sad being a type of  bipolar spectrum disorder even in absence of hypomania or mania symptoms . the limitations of this study include the small sample size , lack of controls and randomization . in future , this study needs to be replicated with better scientific design and these limitations need to be addressed . this study brings to light the fact that sad needs to be looked as type of bipolar disorder for therapeutic purposes .