Risk factors for depression in epilepsy

Depression in epilepsy is multifactorial in nature and has been shown to be influenced by a number of factors.

Gender

In contrast to the increased prevalence of depression in females, a number of the studies have found men to be at a greater risk of depression as compared to females (Fenton 1986, Septien et al. 1993, Strauss et al. 1992).

Sinistrality

Some studies (Ashtuler et al. 1990) have observed that left-handed people with epilepsy have an increased prevalence of psychiatric morbidity, especially depression. A possible explanation advanced is that the expression of left-handedness may indicate early brain injury.

Related neurological conditions

The causative neurological condition responsible for the epilepsy such as multiple sclerosis, cerebrovascular accidents, dementia and head injury may be associated with depression. Taylor (Taylor 1972) and Koch-Weser (Koch-Weser et al. 1988) suggested depression to be more common in patients with a structural lesion; this however, has been refuted by other investigators (Hermann 1989).

Genetic

Family history of psychiatric illness, usually depression (Robertson et al. 1987) and suicide (Hancock 1971), has been associated with an increased incidence of depression.

Structural changes in the medial temporal lobe

There is an emerging literature that links amygdala enlargement (Tebartz van Elst 1999) and hippocampal atrophy (Baxendale 2005) with depression (and other forms of psychopathology) in epilepsy. While the findings are by no means ubiquitous, they pose interesting questions about the role of these structures in the development of depression and the differentiation between its characterological and symptomatic components.

Past history

Past history of behavioural disturbance in infancy (Moller 1990), neurotic disorders (Roy 1979), deliberate self-harm (Palia, 1986) and depression (Lund 1985) have all been implicated in the development of depression.

Learning disabilities and IQ

Patients with learning disability and concomitant epilepsy have been shown to have twice the percentage of psychiatric disorders (including behaviour problems and autism) as compared with patients with epilepsy (Mignone et al. 1970). Psychiatric disorders are also more common in patients who had experienced seizures in the preceding year and have been found to be inversely proportional to IQ.

Age-at-onset and duration of epilepsy