Age and sex
Only a few investigations have shown age to have an influence on the development of PSD. In most studies, particularly those based on multivariate analyses, there is no independent connection between age and the development of PSD. In almost all studies analyzing the relationship between sex and the development of PSD, there was a predisposition to female sex.
Localization and size of lesion
In many studies, the interest focused on whether PSD is more likely in left-hemispheric or right hemispheric, anterior or posterior lesions, with differing findings. The majority of studies found a correlation between left-hemispheric strokes and the development of PSD, and only a few authors found evidence for a relationship between right-hemispheric localization and the development of PSD. Many studies, in turn, showed no correlation, even in multivariate analyses, Astrom et al. found an association between left-sided stroke and the development of PSD in the acute phase only.
However, in later follow-up examinations no association could be found. This resulted in the question of whether a time- dependent component might explain the presence or absence of an association. In a meta-analysis studies Carson et al. of 35 concluded that there was no support for the hypothesis that the risk of depression after stroke is affected by the location of the brain lesion.
Only a few studies have analyzed the relationship between the size of lesion (e.g. estimated by CT imaging) and the development of PSD. While two studies did not demonstrate such a relationship, three other studies found a connection between the likely development of PSD in larger lesions. The latter group demonstrated that only an early-onset PSD was associated with the size of the lesion, as measured 3-6 months later, while this link was not detectable 12-18 months later.
Severity of neurological deficits
Several studies showed a strong relationship between the occurrence of PSD and a worse long-term outcome after stroke. By contrast, this relationship is less strong when comparing the initial neurological deficit in the acute phase of stroke and the future risk of PSD. Astrom et al. clearly showed that this relationship becomes stronger and more significant at a later stage of the disease (after 3 months). This raises the hypothesis that the occurrence of PSD may have a negative effect on the outcome after stroke, or is at least independently associated with a worse outcome. Nevertheless, the question as to whether PSD has a modulatory effect on stroke outcome or is merely a further characteristic of a worse outcome, is difficult to answer.
Pre-stroke social functioning
Psychosocial stress prior to stroke was shown to be an influencing factor in three retrospective studies. Further, it was shown that a limited social network and living alone prior to stroke favored the development of PSD. Tateno et al. found a significant relationship between poor social functioning and the development of late onset PSD.
While a few studies found no link between a previous psychiatric illness and the development of PSD, many authors found an elevated risk of the development of PSD in cases of previous depressive illness. A further study found an association between premorbid phobic disorders and the development of PSD, and two additional studies found a connection with previous alcoholism.
PSD as an Influential Factor Following Stroke
A number of studies have reported increased mortality in patients suffering from PSD. Depending on the time of diagnosis of PSD, the odds ratios vary between 1.5 and 2.6. It has been found that there is an association even after 1-2 years. By contrast, there have been long-term studies (>3 years) which have not found a significant association between PSD and subsequent elevated mortality, It must be assumed that over a longer period of time (>2 years), an increasing number of additional influencing factors will come into play. With regard to the question of causality of an elevated mortality in patients with PSD, it does not appear to be due to suicide, which is in fact under-represented in patients with PSD as opposed to patients with primary depression. However, the link between depression and mortality in patients with cardiovascular disease should be pointed out. In this regard, pathophysiological mechanisms, such as impairment of the autonomic nervous system and a low-grade inflammatory reaction, as well as elevated vasoconstriction and platelet agreeability, in depressed patients must suffice as an explanation.
Length of hospital stay
There are only few studies that have systematically analyzed the link between the extent of a PSD and the length of stay in hospital. Schubert et al. analyzed the association between the extent of depression and the duration of stay in stroke patients compared with patients with amputation and a comparable degree of disability. In this study, there was a significant relationship for stroke patients which was not demonstrable for amputee patients. For the acute phase of stroke treatment, the analysis of hospital statistics by Cushman showed that patients with PSD had a significantly extended stay in hospital. This association was only significant in the acute phase; following diagnosis of depression in the rehabilitation phase it was not demonstrable. Furthermore, other studies have not shown significant differences in the duration of hospital stay between depressed and non-depressed stroke patients.
Most studies have found that PSD has a negative influence on rehabilitation, In some recent studies, it was shown that stroke patients whose depression remitted (due to successful treatment or spontaneous remission) also saw a comparable extent of functional recovery, as initially non-depressed patients had a significantly better extent of functional recovery than patients in whom depression did not remit.
Extent of cognitive impairment
Robinson's group in particular has published many articles about the effects of PSD on cognitive function. Only a few studies were able to show no association between the extent of PSD and loss of cognitive achievement. The definition of cognitive achievement was undertaken by means of the Mini-Mental State Examination, which in principle only provides a crude and imprecise picture. However, the advantage of using this tool was that it allowed a comparison to be made between studies; this could not be guaranteed in the few studies that analyzed cognitive function. For the acute phase, Starkstein et al. initially found a significant difference in regard to cognitive ability between depressed and non-depressed patients.
Subsequently, Downhill and Robinson proved that the influence in the post-acute phase is the strongest and decreases over time. Furthermore, one study found that patients with remitting PSD showed improvement in cognitive function, whereas untreated depressed patients did not, In an analysis by Narushima et al., the authors found that the level of cognitive function following remission of PSD was comparable with the results in non-depressed stroke patients, and that the improvement was stable over 2 years (with stable mood).
Quality of life
The limitation of quality of life (QoL) in stroke patients with PSD as opposed to non-depressed patients seems obvious. In some QoL questionnaires depressive syndromes are explicitly mentioned, resulting in a lower QoL assessment in comparison with non-depressed patients. An association has been found both within the first few months and in the long-term after stroke. Some studies have also shown a reduced QoL in the affected spouse of patients with PSD.
- Huff, W.; Cooper-Mahkorn, D.; Sitzer, M.. Current Medical Literature: Stroke Review, 2004, Vol. 8 Issue 2, p41-50, 10p
Reflection Exercise #5
The preceding section contained information about post-stroke depression. Write three case study examples
regarding how you might use the content of this section in your practice.
What have many studies found concerning the relationship between PSD and mortality? Record the letter of the correct answer the