Track topics on Twitter Track topics that are important to you
The cholinergic system involves the regulation of neurotransmitters and the brain receptors to which they bind. Evidence suggests that the cholinergic system may play a role in the development of depression. Acetylcholine is a neurotransmitter that binds to certain brain receptors called muscarinic cholinergic receptors. Cholinomimetic drugs (drugs that stimulate the cholinergic system) often exacerbate depressive symptoms in people with mood disorders and in healthy individuals. This increase in depressive symptoms may be caused by stimulation of muscarinic acetylcholine receptors (mAChRs), but further study is needed to confirm this. This study will use positron emission tomography (PET) and magnetic resonance imaging (MRI) to study the function of mAChRs in individuals with depression.
Participants in this study will undergo a physical examination, psychiatric interviews, neuropsychological tests, PET and MRI scans, and rating scales of depression, anxiety, and negative thinking symptoms. Questions about behavior and functioning will be asked and blood samples will be collected for genetic analysis.
Several paths of evidence converge in implicating a role for the cholinergic system in the pathophysiology of affective illness. In both unipolar depressed and euthymic bipolar subjects, cholinomimetic drugs (i.e., muscarinic agonists, acetylcholinesterase inhibitors) exacerbate depressive signs and symptoms such as dysphoria, psychomotor retardation, impairment of attention and memory, hypothalamic pituitary adrenal axis hyperactivity and sleep EEG abnormalities. In healthy subjects, the acetylcholinesterase inhibitor physostigmine elicits a range of depressive symptoms including dysphoria, anergia, psychomotor slowing, emotional lability, sleep disturbances, memory and concentration impairment, and with higher doses, tearfulness and depression. These effects have been shown to reflect stimulation of muscarinic receptors. Cholinomimetics also exacerbate behavioral despair in putative animal models of depression. Conversely, the anticholinergic agent biperidine improved symptoms of depression in a placebo controlled study. Moreover, muscarinic cholinomimetics and a choline rich nutrient, lecithin (phosphatidylcholine) exert antimanic effects in bipolar subjects.
Potentially consistent with these observations, depressed subjects exhibit hypersensitivity to cholinomimetic agents. Administration of muscarinic cholinergic agonists, ACh releasing agents or acetylcholinesterase inhibitors induce exaggerated effects on REM density and latency in depressed subjects than in healthy controls. In addition, both manic and depressed bipolar subjects show increased pupillary sensitivity to the muscarinic cholinergic agonist pilocarpine relative to controls.
Despite the data implicating the mAChR receptor system in mood disorders, no direct in vivo investigations of the central mAChR have been performed in depressed subjects. A novel PET radioligand, [(18)F]FP-TZTP was recently developed by Eckelman as a selective agonist of M(2) receptors. Because the M(2) receptor functions predominately as a presynaptic release-controlling autoreceptor, decreased distribution volume (V) of this receptor could conceivably give rise to increased postsynaptic muscarinic receptor sensitivity.
This application proposes a pilot PET study of M(2) receptor distribution volume in currently depressed subjects with major depressive disorder (n=30), currently depressed subjects with bipolar disorder (n=30), and psychiatrically healthy controls (n=30). The proposed pilot study will test the central hypothesis that M(2) receptor V is decreased in regions where they are primarily located presynaptically in depressed subjects relative to healthy controls. The proposed study will advance knowledge regarding the pathophysiology of depression.
National Institutes of Health Clinical Center, 9000 Rockville Pike
National Institutes of Health Clinical Center (CC)
Published on BioPortfolio: 2014-08-27T03:55:39-0400
The goal of the study is to define and measure biological processes that contribute to the underlying pathophysiologic process of peri-partum depression to be used for identifying those at...
Depression is the most common psychiatric disorder. - 3-5% of a given population has major depression. - Less than 50% of the depressed in Denmark are diagnosed with major ...
Postpartum depression is common in mothers early after childbirth and produces harmful effects not only on mothers, but also on infants and young children. Parturietns with prenatal depres...
Microbiome studies may be highlighted as crucial in the development of depression for TBI patients. The microbiota-gut-brain connection may further provide an opportunity for microbiota ma...
Anxious depression is a particularly difficult-to-treat subtype of depression. Patients with anxious depression do not respond as well to currently available antidepressant medications. Ne...
Kinship processes contribute to the experience and interpretation of depression-generating empathy as well as silencing. We explore intersubjective experiences of depression among kin with the aim of ...
As part of a larger epidemiological study of depression among rural Chinese women, we sought to understand their explanatory models of depression. We explored how participants describe depression, to ...
The level of physical activity (PA) and the prevalence of depression both change across the lifespan. We examined whether the association between PA and depression is moderated by age. As sense of mas...
Research linking depression to mortality among people living with HIV (PLWH) has largely focused on binary "always vs. never" characterizations of depression. However, depression is chronic, and is li...
Doctors mainly use scale tests and subjective judgment in the clinical diagnosis of depression. Researches have demonstrated that depression is associated with the dysfunction of the autonomic nervous...
Decompression external to the body, most often the slow lessening of external pressure on the whole body (especially in caisson workers, deep sea divers, and persons who ascend to great heights) to prevent DECOMPRESSION SICKNESS. It includes also sudden accidental decompression, but not surgical (local) decompression or decompression applied through body openings.
Depression in POSTPARTUM WOMEN, usually within four weeks after giving birth (PARTURITION). The degree of depression ranges from mild transient depression to neurotic or psychotic depressive disorders. (From DSM-IV, p386)
Depressive states usually of moderate intensity in contrast with major depression present in neurotic and psychotic disorders.
The prototypical tricyclic antidepressant. It has been used in major depression, dysthymia, bipolar depression, attention-deficit disorders, agoraphobia, and panic disorders. It has less sedative effect than some other members of this therapeutic group.
A propylamine formed from the cyclization of the side chain of amphetamine. This monoamine oxidase inhibitor is effective in the treatment of major depression, dysthymic disorder, and atypical depression. It also is useful in panic and phobic disorders. (From AMA Drug Evaluations Annual, 1994, p311)
Of all the types of Dementia, Alzheimer's disease is the most common, affecting around 465,000 people in the UK. Neurons in the brain die, becuase 'plaques' and 'tangles' (mis-folded proteins) form in the brain. People with Al...
Psychiatry is the study of mental disorders and their diagnosis, management and prevention. Conditions include schizophrenia, severe depression and panic disorders among others. There are pharmaceutical treatments as well as other therapies to help...