Depression subtyping studies

Disturbances of sleep are typical of mood disorders, and belong to the core symptoms of major depression. More than 90% of depressed patients complain of impaired sleep quality [60], Typically, patients suffer from difficulties in falling asleep, frequent nocturnal awakenings, and early morning awakening. Not only is insomnia a typical symptom of depression but, studies suggest, conversely, insomnia may be an independent risk factor for depression. In bipolar disorders sleep loss may also be a risk factor for the development of mania. Hypersomnia is less typical for depression [61] and, in contrast to insomnia, may be related to certain subtypes of depression, such as seasonal affective disorder (SAD). 

Support for a depression taxon comes primarily from subtyping studies. First, Haslam and Beck (1994) tested the taxonicity of several theoretical... 

TCAs in more serious forms of depression such as melancholic or psychotic depression. Some studies have suggested that the SSRls do not work as well as the TCAs in melancholic depression (Roose et al. 1994]. Likewise, one study has suggested that venlafaxine, a drug with a mechanism of action similar to that of the TCAs, was superior to fluoxetine in the treatment of inpatients with melancholic depression (Clerc et al. 1994]. Still, other metaanalyses have failed to find a difference in the efficacy of SSRls versus TCAs in serious forms of depression [Nierenberg 1994]. Nonetheless, given that most studies have employed TCAs, and some debate exists about the utility of SSRls in severe subtypes, it may be prudent to start with a TCA in most patients until the debate is further resolved. For patients who present a significant suicide risk or who have not been able to tolerate TCAs, the SSRls in combination with a standard antipsychotic appears an effective option. 

The anxiolytic activity of several compounds in some, but not all, animal models of anxiety in fact suggests that different receptor subtypes may modulate different types of anxiety as discussed below. It would not be surprising if the specific serotonin links to disorders of anxiety also differ among the various disorders of anxiety such as generalized anxiety versus obsessive-compulsive disorder versus panic disorder versus social phobia versus mixed anxiety depression. Such studies are in progress, and much further research is necessary to clarify the potential links between subtypes of anxiety and subtypes of serotonin receptors. 

Aronson TA, Shukla S, Hoff A, et al. Proposed delusional depression subtypes preliminary evidence from a retrospective study of phenomenology and treatment course. J Affect Disord 1988 14 69-74. 

Both selective and nonselective antagonists for different AR subtypes are widely used in a variety of pathological conditions including hypertension, heart failure, prostate hypertrophy as well as in mental diseases such as depression. Several studies have demonstrated that beta-blockers can behave either as neutral antagonists or inverse agonists at the wild type constitutively active... 

Future directions for research on hypericum may continue the work done in clinical efficacy. More specifically, studies may be of interest that examine its effects in treatment of more severe depression and different subtypes of depression. The comparative efficacy of different hypericum preparations could be further investigated, and optimum dosages need to be established (Linde et al. 1996). Further work is needed to compare hypericum s efficacy and side effects with those of the SSRIs or atypical antidepressants, because published studies to date have only compared it with tricyclics. 

Redrobe JP, Dumont Y, Fournier A, Quirion R (2002a) The neuropeptide Y (NPY) Y1 receptor subtype mediates NPY-induced antidepressant-like activity in the mouse forced swimming test. Neiuopsychopharmacology 26 615-624 Redrobe JP, Dmnont Y, Quirion R (2002b) Neiuopeptide Y (NPY) and depression From animal studies to the hmnan condition. Life Sci 71 2921-2937 Redrobe JP, Dmnont Y, Herzog H, Quirion R (2003) Neiuopeptide Y (NPY) Y2 receptors mediate behaviour in two animal models of anxiety evidence from Y 2 receptor knockout mice. Behav Brain Res 141 251-255... 

I. F. Small et al. 1986), and in our experience the same may hold true for some young patients with schizophrenia. However, confounding variables such as age and gender have not been addressed in these studies. In patients with major depressive disorder, we found no relation between seizure threshold and unipolar versus bipolar or psychotic versus nonpsychotic subtypes. Similarly, Coffey et al. (1995a) found no correlation between initial seizure threshold and severity of depressive illness or the unipolar-bipolar distinction. Finally, we found that history of ECT did not predict seizure threshold (Krueger et al. 1993). 

Given the generally favorable response of PMD to ECT, an important question is whether PMD responds to ECT preferentially over nonpsychotic subtypes of major depression. M. Greenblatt et al. (1964) found that psychotic depression did not show a significantly different response rate to ECT from bipolar depression or even psychoneurotic depression. In contrast, more recent studies (R. P. Brown et al. 1982 C. L. Rich et al. 1984) have found that patients with psychotic depression did not respond preferentially to ECT over other subtypes of depression. However, Charney and Nelson (1981) found that the presence of delusions predicted a more favorable response to ECT in 49 inpatients with depression. The question of whether PMD responds preferentially to ECT over other subtypes remains unanswered. 

Results obtained from studies in gene-targeted mice indicate that ligands which selectively activate or inhibit single muscarinic receptor subtypes may be beneficial for the treatment of a number of diseases including, e.g., Alzheimer s and Parkinson s disease, depression, schizophrenia, and epilepsy. 

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