| The association between atopic disorders and depression: The Northern Finland 1966 Birth Cohort Study | ||
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The definitions of asthma and allergic diseases in general, have mainly been based on symptoms and a phenotype, which is why till now there have existed no widely accepted definitions for different allergic manifestations (Remes 1998). The knowledge about the characteristics of asthma has changed during the last decade and nowadays asthma is considered to be a chronic inflammatory disorder of the airways (Haahtela et al. 1999a).
Many cells play a role in the pathophysiology of asthma, particularly mast cells, eosinophils, and T-lymphocytes. The inflammation in the airways causes, to the patients suffering from asthma, recurrent episodes of wheezing, breathlessness, chest tightness, and cough. These symptoms are usually associated with reversible bronchial obstruction (Remes 1998, Harju 1999). According to its etiology, asthma can be divided into the extrinsic (allergic/atopic) and intrinsic (non-allergic) types (Nasr et al. 1981, Haahtela et al. 1999a, Laitinen et al. 2000a).
Asthma is the most prevalent chronic disease in childhood (Galil 2000), and childhood asthma is frequently, in fact in over 80% of the cases, associated with allergy (Remes & Korppi 1996). The proportion of atopic asthma decreases with the increase of age and in adulthood the asthma is in about 60% of all cases atopic in nature (Laitinen et al. 2000a).
With regard to psychiatric co-morbidity, increased rates of depression and depressive symptoms have been found in patients with asthma (Brown et al. 2000, Centanni et al. 2000, Goethe et al. 2001). On the other hand, higher than normal rates of IgE-mediated allergies (including asthma) have been reported from patients with depression (Nasr et al. 1981, Sugerman et al. 1982).
Atopic dermatitis (AD) is a common inflammatory skin disorder. Its prevalence ranges from 5% to 13% among children in the industrialized Western countries. The frequency of AD has been noted to have increased, especially in urban areas, the estimated current incidence being even as high as 12% as reviewed by Buske-Kirschbaum et al. (2001).
The main symptoms of AD are dry skin, papules, lichenification, eczematous inflammation and an intense itching (Buske-Kirschbaum et al. 2001). In the majority of cases, AD begins in infancy. The pattern of AD varies with age, but a general dryness of the skin may persist throughout life. In infancy, AD usually starts on the face. During childhood the eczema is affecting mainly the elbow and knee flexures as well as wrist and ankles. In adults, eczema is distributed to the face, upper body, flexures and extremities. It has been estimated that symptoms of AD remit spontaneously before the age of 10 in the majority of the affected children (Hunter et al. 1990, Kalimo & Hannuksela 1999). However, symptoms may relapse in stressful life situations, which are often accompanied by an exacerbation of AD (Hunter et al. 1990, Buske-Kirschbaum et al. 2001). It has been suggested that psychosocial stress and skin condition in AD are bidirectionally related, and eventually, via a vicious circle of emotional stress and worsening skin condition the situation may also lead to the chronification of AD symptoms (Buske-Kirschbaum et al. 2001).
Allergic rhinitis, like asthma, is an inflammatory disorder of the airways (Malmberg & Rinne 1999). The cardinal symptoms of allergic rhinitis are sneezing, watery nasal discharge and nasal obstruction. In addition, many patients who are suffering from allergic rhinitis also have eye symptoms; allergic conjunctivitis is known to be commonly associated with allergic rhinitis (Remes 1998, Abbas et al. 2000). Allergic rhinitis can be divided into the seasonal (hay fever) and nonseasonal allergic rhinitis.
In Finland, pollen from broad-leaved trees, grasses and the composite flowers are the commonest allergens causing the typical symptoms of seasonal allergic rhinitis, whereas animal dusts and dust mites are the most prevalent allergens behind the nonseasonal allergic rhinitis (Malmberg & Rinne 1999). In respect to the psychiatric co-morbidity, allergic rhinitis has been found to be associated with high rates of depression and anxiety disorders (Cuffel et al. 1999).
Allergic conjunctivitis is a common cause of conjunctivitis in general. It can be the only manifestation of atopic allergy, but usually it is associated with allergic rhinitis, atopic eczema or asthma (Kari & Hannuksela 1999).