**5. Associated diseases**

Alopecia areata is associated with many diseases, including other autoimmune diseases, atopy, ophthalmologic findings and psychiatric comorbidities.

Among autoimmune disorders, the two main associations are with thyroid disease and vitiligo [17]. Incidence of thyroid disease varies from 8% to 28% in patients with alopecia areata, compared with only 2% of the normal population. Among thyroid disorders, hypothyroidism is the most frequent association. [18] Prevalence of antithyroid antibodies is shown to be increased, but thyroid antibodies do not have any clinical correlation with disease severity [19]. Alopecia areata has also been shown to have a significant association with vitiligo; patients have a fourfold greater incidence of vitiligo compared with normal population. There are also reported associations of alopecia areata with pernicious anemia, lupus erythematosus, myasthenia gravis, rheumatoid arthritis, polymyalgia rheumatica, ulcerative colitis, and lichen planus [8]. A very strong disease association with the autosomal recessive disease autoimmune polyglandular syndrome type 1 (APS-1, chronic hypoparathyroidism-mucocutane-

**Figure 2.** A patient with alopecia universalis having total loss of scalp hair and eyebrows.

Nail changes are observed in up to 7–66% of patients [15]. The nail matrix may be affected, resulting in pitting of the nail plate, which is the most common nail involvement in alopecia areata [6]. Other nail features found in alopecia areata are trachyonychia, Beau's line, onychorrhexis, onychomadesis, koilonychias, punctuate or transverse leukonychia, and red-spot-

Alopecia areata is associated with many diseases, including other autoimmune diseases,

Among autoimmune disorders, the two main associations are with thyroid disease and vitiligo [17]. Incidence of thyroid disease varies from 8% to 28% in patients with alopecia areata, compared with only 2% of the normal population. Among thyroid disorders, hypothyroidism is the most frequent association. [18] Prevalence of antithyroid antibodies is shown to be increased, but thyroid antibodies do not have any clinical correlation with disease severity [19]. Alopecia areata has also been shown to have a significant association with vitiligo; patients have a fourfold greater incidence of vitiligo compared with normal population. There are also reported associations of alopecia areata with pernicious anemia, lupus erythematosus, myasthenia gravis, rheumatoid arthritis, polymyalgia rheumatica, ulcerative colitis, and lichen planus [8]. A very strong disease association with the autosomal recessive disease autoimmune polyglandular syndrome type 1 (APS-1, chronic hypoparathyroidism-mucocutane-

ted lunula [16]. Nail disease may precede, follow, or coexist with active hair loss [2].

atopy, ophthalmologic findings and psychiatric comorbidities.

**Figure 1.** Circular area of nonscarring alopecia incidentally found in an adult patient.

**5. Associated diseases**

108 Hair and Scalp Disorders

ous candidiasis-autoimmune adrenal insufficiency) was recently reported [20]. Patients with Down's syndrome or Turner's syndrome also have increased risk of alopecia areata [17].

Atopic disorders, namely allergic rhinitis, asthma, and atopic dermatitis have been linked to alopecia areata. They have been found to occur in more than 40% of patients with alopecia areata, whereas their prevalence in the general population is estimated to be around 20% [17].

Interestingly, there is a decreased incidence of type 1 diabetes in alopecia areata patients and an increased incidence in their relatives. It was proposed that alopecia areata may have a protective effect against type 1 diabetes in predisposed individuals [21].

Ocular alterations, such as asymptomatic punctate lens opacities, and fundus changes can occur in up to 50% of patients with alopecia areata [22].

There may be a high psychiatric morbidity in alopecia areata patients. Depression, increased level of anxiety, generalized anxiety disorder, social phobia, posttraumatic stress disorder, and suicidal thoughts are among the reported psychiatric disturbances [23].

Incidence of nuchal nevus flammeus was reported to be increased in alopecia areata patients, especially in those showing a more severe course of the disease [24].

**Figure 3.** Reticular type alopecia areata with a net-like pattern.
