ACTH 4-9 analogue (Org 2766) in depressed elderly patients. II. Effect on memory and vigilance

Antidepressant versus placebo for depressed elderly

BACKGROUND

Depression warranting intervention is found in ten percent of people over the age of 60. Older depressed people are more likely to die than non-depressed. Relatively few receive therapeutic interventions, and those that do, tend to receive low dose antidepressant therapy. Depression in older people is thought to differ in terms of aetiology, presentation, treatment and outcome than in younger people. Concomitant physical illness and increasing social, physical and neurophysiological diversity are associated with the ageing process. Consequently drug treatment of older patients is often carried out in institutions and on patients suffering from multiple physical problems.

OBJECTIVES

To determine the efficacy of antidepressant medication compared with placebo in the treatment of depression in older patients.

SEARCH STRATEGY

The search strategy incorporated: electronic literature searches of databases held by the Cochrane Collaboration Depression, Anxiety and Neurosis Review Group (CCDAN) (see Collaborative Review Group Search Strategy). Reference lists of related reviews and references of located studies. Contact was made with authors working in the field.

SELECTION CRITERIA

All randomised, placebo controlled trials using antidepressants in the treatment of the presenting episode of depression in patients described as elderly, geriatric senile or older adult.

DATA COLLECTION AND ANALYSIS

Two types of data were extracted (if available) from each study. The first type of data was dichotomous data, this consisted of recovered/not recovered. The second, continuous data,included: Hamilton Depression Rating Scale (HAM-D), Montgomery-Asberg Rating Scale (MADRS) and other depression rating scale scores. An analysis using Peto Odds ratios for the dichotomous data and weighted mean difference for continuous data was performed using RevMan 3.1. The presence of heterogeneity of treatment effect was assessed.

MAIN RESULTS

Seventeen trials contributed data to the analyses comparing the efficacy of antidepressant treatment and placebo. Analyses of efficacy was based on 245 patients treated with TCAs (223 with placebo), 365 patients treated with SSRIs (372 with placebo) and 58 patients treated with MAOIs (63 with placebo). The standardised effect size for the three groups respectively were: TCAs; OR: 0.32 (0.21,0.47), SSRIs; OR; 0.51 (0.36,0.72), MAOIs: 0.17 (0.07,0.39).

REVIEWER'S CONCLUSIONS

TCAs, SSRIs and MAOIs are effective in the treatment of older community patients and inpatients likely to have severe physical illness. At least six weeks of antidepressant treatment is recommended to achieve optimal therapeutic effect. There is little evidence concerning the efficacy of low dose TCA treatment. Further trials are required before low dose TCA treatment is routinely recommended.

Chronic administration of Org2766 and morphine counteracts isolation-induced increase in social interest: implication of endogenous opioid systems

In complex behaviors, like social behavior, the MSH/ACTH (4-9) analog Org2766 is found to counteract changes in social interest caused by preceding housing or test conditions. Previous studies have indicated an involvement of endogenous opioid systems in these outcomes. In the present study we have counteracted isolation-induced enhanced social interest by chronic treatment (7 x every 48 h) with Org2766 or with the opiate morphine. These effects were blocked by previous administration of naloxone. However, in group-housed animals, both Org2766 and morphine treatment did not result in changes in social activity as compared to saline-treated group-housed controls. Chronic administration of naloxone in group-housed rats resulted in an increase in social interest. These results are discussed in relation to possible function of Org2766 and morphine as a substitute for the release of endogenous opioids caused by social contact.

Neuropsychological abnormalities in patients with pituitary tumours

Neuropsychological assessment of 65 patients with pituitary tumours revealed impairment of memory and executive function. This did not appear to be related to the size or type of tumour or the effects of radiotherapy or surgery. It is possible that the problems arose from multiple unconnected factors but this observation lends support to the suggestion that pituitary or hypothalamic hormones have a role in the modulation of memory and behavioural pathways. Whatever the cause, neuropsychological impairment is common in patients with pituitary tumours and is an aspect of their disability which has received insufficient attention in the past.

Effects of the ACTH4-9 analog Org2766 on brain plasticity: modulation of excitatory neurotransmission?

ACTH-like neuropeptides have been investigated in various paradigms such as cognition, neuronal damage and neuronal excitation. All their effects may be collectively described as modulation of neural plasticity. However, the mechanism of action accounting for these effects remains to be demonstrated. This report is an overview of the data and has incorporated some additional findings of the influence of the ACTH4-9 analog, Org2766, on neuronal excitation, especially in the hippocampus. An interaction with NMDA receptors may account for the various aspects of plasticity. Based on recent findings demonstrating that the ACTH4-9 analog counteracts both the NMDA antagonist, AP5, and NMDA-induced explosive running behavior, the hypothesis is put forward that glutamatergic neurotransmission is involved in behavioral changes induced by the ACTH4-9 analog.

An ACTH4-9 analog enhances social attention in aging rats: a longitudinal study

Effect of chronic treatment of the ACTH4-9 analog, Org2766, on social attention was studied longitudinally in aging rats. A 6-week treatment temporarily enhanced specific combinations of behaviors of two interacting animals. During a 6-month treatment social attention of treated animals remained at the same level, whereas control animals showed a gradual decrease. Two months after the treatment was ceased this effect on social attention was still present; moreover, the peptide-treated animals performed better in a spatial water maze task three months after the last injection. In addition, the nerve conduction velocity of the major caudal nerves and the sciatic nerve were measured; aged, peptide-treated animals preserved their conduction velocity. The present study shows beneficial long-lasting effects of the ACTH4-9 analog in aging rats on complex behavioral indices and on a physiological measure.

Pre- and postnatally administered ACTH, Organon 2766 and CRF facilitate or inhibit active avoidance task performance in young adult mice

This study investigated the effect of learning/memory-related neuropeptides on behavioral task performance in later life. A 1 mg/kg dosage of adrenocorticotropic hormone 4-9, Organon 2766, ACTH/MSH 4-10, ACTH 1-24, CRF, or diluent was subcutaneously injected into either pregnant females or into newborn pups during specific neural developmental windows. Each of the progeny was trained in an active-avoidance task and tested for acquisition on postpartum days 35-37. The mice were then tested for memory task performance and reacquisition on days 42-44 postpartum using the identical experimental paradigm as that used in the training sessions. Prenatal treatment with these memory-related neuropeptides resulted in significant facilitation of learning/memory task performance in male and female mice treated with Organon 2766 (p less than 0.001), and a significant inhibition of learning/memory task performance in males and females treated with ACTH 1-24 (p less than 0.01). Additional sex-specific performance facilitations and inhibitions resulted from the pre- or postnatal administration of the various neuropeptides used in this study. These results suggest that neuropeptides, when available in increased amounts during specific neural developmental windows, can significantly improve or suppress related behavioral performance capability in later life.