الفهرس 
Introduction and Aim of the Work
Neurobiological Aspects of DepressionOnly 14 pages are availabe for public view
 |  | from | 200 |  |  |
| | | from | 200 | | |
Abstract
The description of psychiatric symptoms in neurologic disorders has a long history, dating back to the times of
Hippocrates, but such interest accelerated in the European literature of the 19th century, when the distinction between neurology and psychiatry as separate medical disciplines was not countenanced. With the growing rift between an organically based neurology and a psychologically based psychiatry in the first six decades of the 20th century, interest
in such comorbidities waned, in spite of such obvious clinical presentations of, for example, postictal psychoses, or the dementias seen in conditions such as Parkinson ’ s disease or multiple sclerosis.
Depressive disorders are the fourth medical disorder with a significant burden on the individual, the family, and society worldwide. In the general population, their lifetime prevalence has been estimated to be 26% for women and 12% for men (Akiskal, 2005).
In patients with neurologic disorders, the lifetime prevalence of depressive disorders ranges between 30% and
50%. For example, in patients with epilepsy, a lifetime prevalence of 34.2% (25.0 – 43.3%) was identified in a
Canadian population- based study (Tellez-Zenteno et al., 2007).
The lack of communication between psychiatrists and neurologists is one of the most incomprehensible phenomena
in modern medicine, as most (if not all) neurologic disorders affecting the central nervous system are associated with a psychiatric comorbidity, of which depression is the most common. And yet, in a majority of patients, depression remains unrecognized and untreated, as most neurologists
focus only on the identification of neurologic signs and symptoms and their treatment.
Nevertheless, the impact of a comorbid depressive disorder in the life of these patients can be as devastating as
and often more disabling than the actual neurologic disorder.
When investigated, a lifetime history of depression can be identified in one out of every three to four patients suffering from any of the major neurologic conditions including
epilepsy, stroke, migraine, multiple sclerosis, dementia, movement disorders.
Contrary to old assumptions, depression is not simply a “reactive process” to the limitations and obstacles caused by
the underlying neurologic disorder. In fact, there is a complex relation between depression and several neurologic disorders, as evidenced by the existence of a bidirectional relation between depression and conditions like epilepsy, stroke,
migraine, Parkinson ’ s disease and possibly also dementia.
In other words, not only are patients with these neurologic conditions at higher risk of developing depression, but patients with depression are at a higher risk of developing one of these neurologic disorders.
This bidirectional relation does not establish causality but suggests the existence of common pathogenic mechanisms operant in the psychiatric and neurologic conditions.
The complex relation between depression and neurologic disorders has significant clinical implications that
should be of great concern to neurologists, as the existence of a comorbid depressive disorder is associated with a worse course and poorer response to treatment of the neurologic disorder. Furthermore, comorbid depression has been found
to be an independent risk factor for a poor quality of life and increased suicidal risk. It accounts for higher medical costs (not related to the psychiatric treatment) and lesser
compliance with the neurologic treatment. Accordingly, one would expect to find a plethora of data on the impact of the treatment of depression on the course of the neurologic disorder.
In fact, a review of the literature reveals a paucity of studies on the treatment of depression in most neurologic disorders. This problem is compounded by the limited access of patients to psychiatric treatment because of financial reasons, reluctance on the part of patients and their family to seek psychiatric evaluations, and a discomfort on the part of psychiatrists to treat patients with neurologic disorders