The etiology of depression in Parkinson's disease patients

Risk of depression after Parkinson's disease, stroke, multiple sclerosis, and migraine in an Iranian population and assess psychometric characteristics of three prevalent depression questionnaires

Objective

We aim to evaluate the prevalence of depression in disorders including multiple sclerosis (MS), Parkinson's disease (PD), migraine, and stroke. Also, we detect risk factors for depression occurrence within each disorder. Moreover, we compare the risk factors in these four common neurologic disorders. In advance, we assess the three surveys in order to better comprehend their distinctions.

Background

Depression is a globally prevalent Psychologic disorder and common co-morbidity in neurological diseases. However, it is mostly underdiagnosed in chronic patients and causes numerous adverse effects.

Methods

We used the database of neurology specialty clinics in a hospital in Tehran, the largest city of Iran. Five hundred nineteen patients, including 105 PD patients, 101 patients with stroke, 213 cases with MS, and 100 Migraine patients, were assessed. They were asked about their chief characteristics and disease-specific variables that may cause depression. Moreover, depression criteria were measured with three internationally used scales to study their variances.

Results

Overall, the prevalence of depression in PD, stroke, MS, and migraine, according to the BDI-II scale, were 43.8%, 38.6%, 45.1%, 37.6%, and according to HDRS scale, were 56.2%, 51.5%, 39.4%, and 43.6% respectively. Finally, according to DSM-XC the depression prevalence were 64.8%, 34.7%, 36.2%, and 67.3% respectively. Possible risk factors of depression were lower educational level, disease severity, socioeconomic level, marital or employment status, female gender, higher age, and consumption of some specific drugs.

Conclusion

Depression is a widespread disorder in chronic neurologic conditions. Our data suggests the odds of depression in neurologic disorders depend on the characteristics of the patient and the features of the disease.

N-3 (Omega-3) Fatty Acids: Effects on Brain Dopamine Systems and Potential Role in the Etiology and Treatment of Neuropsychiatric Disorders

BACKGROUND & OBJECTIVE

A number of neuropsychiatric disorders, including Parkinson's disease, schizophrenia, attention deficit hyperactivity disorder, and, to some extent, depression, involve dysregulation of the brain dopamine systems. The etiology of these diseases is multifactorial, involving genetic and environmental factors. Evidence suggests that inadequate levels of n-3 (omega- 3) polyunsaturated fatty acids (PUFA) in the brain may represent a risk factor for these disorders. These fatty acids, which are derived from the diet, are a major component of neuronal membranes and are of particular importance in brain development and function. Low levels of n-3 PUFAs in the brain affect the brain dopamine systems and, when combined with appropriate genetic and other factors, increase the risk of developing these disorders and/or the severity of the disease. This article reviews the neurobiology of n-3 PUFAs and their effects on dopaminergic function.

CONCLUSION

Clinical studies supporting their role in the etiologies of diseases involving the brain dopamine systems and the potential of n-3 PUFAs in the treatment of these disorders are discussed.

Peripheral vagus nerve stimulation significantly affects lipid composition and protein secondary structure within dopamine-related brain regions in rats

Recent immunohistochemical studies point to the dorsal motor nucleus of the vagus nerve as the point of departure of initial changes which are related to the gradual pathological developments in the dopaminergic system. In the light of current investigations, it is likely that biochemical changes within the peripheral nervous system may influence the physiology of the dopaminergic system, suggesting a putative role for it in the development of neurodegenerative disorders. By using Fourier transform infrared microspectroscopy, coupled with statistical analysis, we examined the effect of chronic, unilateral electrical vagus nerve stimulation on changes in lipid composition and in protein secondary structure within dopamine-related brain structures in rats. It was found that the chronic vagal nerve stimulation strongly affects the chain length of fatty acids within the ventral tegmental area, nucleus accumbens, substantia nigra, striatum, dorsal motor nucleus of vagus and the motor cortex. In particular, the level of lipid unsaturation was found significantly increasing in the ventral tegmental area, substantia nigra and motor cortex as a result of vagal nerve stimulation. When it comes to changes in protein secondary structure, we could see that the mesolimbic, mesocortical and nigrostriatal dopaminergic pathways are particularly affected by vagus nerve stimulation. This is due to the co-occurrence of statistically significant changes in the content of non-ordered structure components, alpha helices, beta sheets, and the total area of Amide I. Macromolecular changes caused by peripheral vagus nerve stimulation may highlight a potential connection between the gastrointestinal system and the central nervous system in rat during the development of neurodegenerative disorders.

N-3 (omega-3) Fatty acids in postpartum depression: implications for prevention and treatment

A growing body of clinical and epidemiological evidence suggests that low dietary intake and/or tissue levels of n-3 (omega-3) polyunsaturated fatty acids (PUFAs) are associated with postpartum depression. Low tissue levels of n-3 PUFAs, particularly docosahexaenoic acid (DHA), are reported in patients with either postpartum or nonpuerperal depression. Moreover, the physiological demands of pregnancy and lactation put childbearing women at particular risk of experiencing a loss of DHA from tissues including the brain, especially in individuals with inadequate dietary n-3 PUFA intake or suboptimal metabolic capabilities. Animal studies indicate that decreased brain DHA in postpartum females leads to several depression-associated neurobiological changes including decreased hippocampal brain-derived neurotrophic factor and augmented hypothalamic-pituitary-adrenal responses to stress. Taken together, these findings support a role for decreased brain n-3 PUFAs in the multifactorial etiology of depression, particularly postpartum depression. These findings, and their implications for research and clinical practice, are discussed.

Dopamine receptor alterations in female rats with diet-induced decreased brain docosahexaenoic acid (DHA): interactions with reproductive status

Decreased tissue levels of n-3 (omega-3) fatty acids, particularly docosahexaenoic acid (DHA), are implicated in the etiologies of non-puerperal and postpartum depression. This study examined the effects of a diet-induced loss of brain DHA content and concurrent reproductive status on dopaminergic parameters in adult female Long-Evans rats. An alpha-linolenic acid-deficient diet and breeding protocols were used to produce virgin and parous female rats with cortical phospholipid DHA levels 20-22% lower than those fed a control diet containing adequate alpha-linolenic acid. Decreased brain DHA produced a significant main effect of decreased density of ventral striatal D(2)-like receptors. Virgin females with decreased DHA also exhibited higher density of D(1)-like receptors in the caudate nucleus than virgin females with normal DHA. These receptor alterations are similar to those found in several rodent models of depression, and are consistent with the proposed hypodopaminergic basis for anhedonia and motivational deficits in depression.

Prevalence, etiology, and treatment of depression in Parkinson's disease

Parkinson's disease (PD) is primarily a disease of elderly individuals with a peak age at onset of 55 to 66 years. It is characterized by bradykinesia, rigidity, tremor, and postural instability; and affects approximately 1 million individuals in the US and is the second most common neurodegenerative disease next to Alzheimer's disease. The motor symptoms of PD are the focus of pharmacotherapy, yet the nonmotor symptoms (e.g., dementia, psychosis, anxiety, insomnia, autonomic dysfunction, and mood disturbances) can be the most disturbing, disabling, and misunderstood aspects of the disease. Depressive symptoms occur in approximately half of PD patients and are a significant cause of functional impairment for PD patients. There is accumulating evidence suggesting that depression in PD is secondary to the underlying neuroanatomical degeneration, rather than simply a reaction to the psychosocial stress and disability. The incidence of depression is correlated with changes in central serotonergic function and neurodegeneration of specific cortical and subcortical pathways. Understanding comorbid depression in PD may therefore add to the understanding of the neuroanatomical basis of melancholia.

Self-reported Depressive Symptoms in Myasthenia Gravis

It is well known that patients with a chronic medical illness experience major depression at a higher rate than the general population. The purpose of this study was to determine the frequency of depression among patients with myasthenia gravis (MG) who were referred to a Muscular Dystrophy Association clinic. Forty-five patients with a diagnosis of MG were evaluated with a self-administered survey regarding various typical somatic and psychologic symptoms of depression (the Beck Depression Inventory [BDI]) and then scored according to the BDI guidelines. Thirty-three percent of these patients generated scores suggestive of depression (24% were categorized as mildly depressed, 7% as moderately depressed, and 2% as severely depressed). These results suggest that patients with MG patients experience depression at a higher rate than the general population and at a similar rate as patients with other chronic illnesses.

The frissonnant mutant mouse, a model of dopamino-sensitive, inherited motor syndrome

The frissonnant (fri) mutation is an autosomic recessive mutation which spontaneously appeared in the stock of C3H mice. fri mutant mice have locomotor instability and rapid tremor. Since tremor ceases when mutant mice have sleep or are anaesthetized, and because of their obvious stereotyped motor behavior, these mice could represent an inherited Parkinsonian syndrome. We show here that the fri/fri mouse fulfills two out of the three criteria required to validate an experimental model of human disease, that is isomorphism, homology and predictivity. Indeed, fri/fri mice present an important motor deficit accompanying visible tremor and stereotypies. They display some memory deficits as in human Parkinson's desease. l-Dopa and apomorphine (dopaminergic agonists), ropinirole (selective D2 agonist), and selegiline (an monoamino-oxidase B [MAO-B] inhibitor) improve their clinical status. However, neither anatomopathological evidence of nigrostriatal lesion, nor decrease in tyrosine hydroxylase production could be seen.

Parkinson's disease symptoms--patients' perceptions

Self-assessment is significant for the accurate evaluation of patient' needs. This study examined the frequency and severity of symptoms reported by 39 patients with Parkinson's disease and compared them with symptoms suggested by the literature and by specialists as bothering Parkinson's patients. Four categories of symptoms were examined: (a) motor disability or activity loss, (b) mental change, (c) psychosocial difficulties, and (d) nonspecific symptoms. The findings show that there was correspondence between expert judgements and subjects' reports regarding symptoms such as dyskinesia/tremor as well as walking, freezing gait, and changing position. Symptoms such as dressing self, getting in/out of bed, morning stiffness and deficit in cognitive sequencing, which experts described as characteristic of Parkinson's disease patients, bothered subjects less. In general, patients mental and psychosocial symptoms were higher in their frequencies and perceived severity than problems of performing activities of daily living.

Depression in Parkinson's disease

Depression occurs in 40% to 50% of Parkinson's disease (PD) patients. From research over the last decade, this co-occurrence appears to be more than an emotional reaction to disability. Replacement of the neurotransmitter, dopamine, benefits the PD motor functions, and the neurotransmitter, serotonin, in antidepressants, reduces depressive symptoms. However, identification of the physiological linkage between PD and depression continues to evade research efforts.

Potential antidepressive properties of amantadine, memantine and bifemelane

The effects of amantadine, its dimethyl derivative, memantine and the chemically unrelated compound bifemelane were tested for antidepressant activity. Reserpine-induced hypothermia and the forced swim test (Porsolt test) were selected for this purpose. In the former test amantadine and bifemelane but not memantine were effective. In the forced swim test all three agents produced antidepressive-like activity (decreased immobility time), but in case of bifemelane it was less pronounced. The effect in the forced swim test was specific i.e. it was apparently not the result of an increase in general activity as evidenced by control experiments in the open field. The mechanism of amantadine and memantine action may involve indirect dopaminomimetic activity resulting from the blockade of NMDA receptors. However in reserpine-induced hypothermia this explanation is not valid considering the lack of effect of memantine and positive action of amantadine. Hence, amantadine may have an additional central sympathomimetic action that memantine is lacking. Bifemelane antidepressant-like activity might be attributed to an enhancement of noradrenergic transmission. We suggested that amantadine and bifemelane could be particularly useful therapeutically when depressive symptoms are present in patients suffering from Parkinson's disease and dementia.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) disrupts social memory/recognition processes in the male mouse

Male mice treated with MPTP or vehicle were tested for their ability to demonstrate a memory-recognition response as evaluated in a habituation-dishabituation task. Treatment with MPTP severely disrupted the male's habituation-dishabituation response profile compared to vehicle treated animals. Administration of L-DOPA at 45 min prior to behavioral testing in MPTP animals restored their performance on the habituation-dishabituation test to levels observed in vehicle treated animals. There was also a tendency for L-DOPA to produce enhanced responsiveness in vehicle treated animals. Mice treated with MPTP had significantly reduced concentrations of norepinephrine within the olfactory bulb and hippocampus. Vehicle treated mice administered L-DOPA had significantly increased dopamine concentrations within the corpus striatum. These results suggest that, in addition to its putative effects upon the nigrostriatal dopaminergic system and motor behavior, MPTP is also exerting substantial effects upon other systems. In particular, the noradrenergic system and its potential involvement with memory/recognition processes in the CD-1 mouse appears to be very sensitive to the neurotoxic effects of MPTP.