Seborrheic Dermatitis and Dandruff

Seborrheic Dermatitis (SD) and dandruff are common dermatological problems. It is estimated that SD and dandruff combined affect half of the adult population. However their etiology is not well understood. The skin changes are thought to result from an inflammatory response to a common skin organism, Malassezia yeast. 

In infants up to three months of age (42%), SD involves the scalp (termed “cradle cap”), the face, and diaper area. In adolescents and adults (1-3%), SD affects the scalp and other seborrheic areas on the face, upper-chest, axillae, and inguinal folds.Men are affected more frequently than women (3.0% vs. 2.6%) in all age groups, suggesting that SD may be associated with sex hormones such as androgens.

SD is more prevalent in immune-compromised patients such as HIV/AIDS (30-83%), organ transplant, and lymphoma. Most cases of SD in HIV patients are diagnosed with CD4+ T lymphocyte counts between 200 and 500/mm3. These observations suggest that immunological defects may play a role in SD.

SD is also associated with neurological disorders and psychiatric diseases, including Parkinson’s disease, neuroleptic induced parkinsonism, tardive dyskinesia, traumatic brain injury, epilepsy, facial nerve palsy, spinal cord injury and mood depression, chronic alcoholic pancreatitis, hepatitis C virus , and in patients with congenital disorders such as Down syndrome. 

Comparing with SD, dandruff is much more common, and affects approximately 50% of the general adult population worldwide( males > females). Dandruff starts at puberty, reaches peak incidence and severity at the age of about 20 years, and becomes less prevalent among people over 50. Incidence varies between different ethnic groups: in a study in the U.S. and China, dandruff prevalence was 81–95% in African Americans, 66–82% in Caucasians, and 30–42% in Chinese.

 (Borda, L. and Wikramanayake, T., 2015)

Reference 

Borda, L. and Wikramanayake, T., 2015,' Borda, L. and Wikramanayake, T., 2015) ', J Clin Investig Dermatol., vol. 3, no. 2, pp. 10.

Clark, G. et al., 2015,' Diagnosis and Treatment of Seborrheic Dermatitis ', Am Fam Physician., vol. 91, no. 3, pp. 185-190.