EFFICACY OF ANTIDANDRUFF FORMULATIONS 77 0 ,ol- / • •o I io Jan.- March ß June .•.• J uly-,Sep ••ct.-Dec. , I 2 • 4 5 6 7 8 Grade Figure 2. Distribution of grades of scaling in relation to the four seasons Procedure The same 1,033 individuals were distributed by grades for each month of the year. Changes in frequencies were analyzed for deviations from that ex- pected if no seasonal effects were present. Results A seasonal variation of a statistically significant degree was indeed ascer- tainable (p = •0.01). For illustrative purposes, the frequencies of the various grades are shown by quarters (Fig. 2). This seasonal rhythm is very evident with regard to the frequency of grades 1 in spring, for example, nearly 30% are grade 1 while in winter the frequency falls to only 10%. The contribution to x 2 showed that the seasonal deviation could be largely attributed to an in- crease in grades i and 2 in the spring and summer while in the fall grades 6 and above were higher than at any other season.

78 JOUttNAL OF THE SOCIETY OF COSMETIC CHEMISTS Comment Seasonal shifts with a summer downturn are probably greater than our fig- ures show. We always find it more difficult to mobilize dandruff panels in the summer. This was a retrospective analysis and more subjects are represented in the winter than the summer group. Distribution of Dandruff It is commonly believed that dandruff is a patchy process. It has become the practice, therefore, to divide the scalp into segments, each of which is graded separately a composite score is then calculated. Van Abbe originally evaluated 25 imaginary segments (13). Orentreieh and his colleagues prob- ably are closer to the norm, scoring 9 separate sections (14). Various devices such as fencing caps have been utilized as stencils to divide the scalp into re- gions of equal size ( 13 ). We, however, make one global estimate after scratch- ing the surface at several points with a tongue blade. We investigated the question of patchiness by doing duplicate eorneoeyte counts in symmetrical sites on opposite sides of the scalp. Nonconcordance would signify an unequal distribution. Procedure Four days after a bland shampoo, corneocyte counts were done on 148 subjects on the left and right sides of the vertex 5 cm from the midline. In another group 92 counts were done 7 days after a shampoo. Results Four days after the shampoo there was a high degree of correlation between duplicate samples from opposite sides (r= 0.847, 95% confidence limits 0.80, 0.89) (Fig. 3). This strong correlation increased in the 7-day group (r = 0.904, 95% confidence litnits 0.85, 0.93). The variation between sides was re- markably small whether or not the subjects had dandruff. This too bespeaks validity of the method. Comment The results indicate that dandruff is a uniform, diffuse rather than patchy process. This accords with all our clinical observations. We can think of two explanations for the idea of patchiness. The first arises if dislodged scales are included in the evaluation. The distribution of these through the hair will be influenced by many factors such as hair styling and brushing. Secondly, dandruff is often mistaken for seborrheie dermatitis.