PHENYLALANINE
Plasma tryptophan and five other amino acids in depressed and normal subjects.
Archives of General Psychiatry 38(6):642-646, 1981
The ratio of plasma tryptophan (TRP) to five other neutral amino acids (TRP/5aa ratio) was examined in depressed Ss and normal controls. Plasma TRP (free and total), phenylalanine (PHE), tyrosine (TYR), leucine, isoleucine, and valine were measured on three days. When depression was most severe, depressed patients had lower TRP/5aa ratios and total TRP levels and higher PHE and TYR levels. As Hamilton depression scores improved, the plasma TRP/5aa ratios increased significantly. The finding tends to support the idea that changes in brain serotonin level reflect changes in depression severity. 41 references.
Trace amine deficit in depressive illness: the phenylalanine connexion.
Acta Psychiatrica Scandinavica 61(Suppl. 280):29-39, 1980
Preliminary studies of deficiencies of three trace amines (phenylethylamine, tyramine, and octopamine) in patients with depressive illness are described. Data from two groups of depressed Ss and control Ss indicate that the mean output of p-hydroxyphenylacetic acid and p-hydroxymandelic acid in urine is significantly lower in depressed patients than in control Ss. Both the patients as a whole and the male patients as a subset possessed significantly lower cerebrospinal fluid phenylacetic acid concentrations than did control Ss. Three patients characterized by severe endogenous depression features and who responded poorly to tricyclic drugs had very low excretion values of p-hydroxymandelic acid and p-hydroxyphenylacetic acid, although the other metabolites were normal. A panel discussion of these findings is appended. 40 references.
Phenylalanine levels in endogenous psychoses.
Psychiatrie, Neurologie und Medizinische Psychologie 32(10):631-633, 1980
The effects of phenylalanine levels on 65 depressive and psychotic patients were made over a period of 14 days. Patients were kept on a protein free diet for 24 hours prior to the test. Patients received doses of L-phenylalanine at a rate of 100mg/kg. Blood samples drawn hourly were analyzed for amino acid content. Phenylalanine doses were found to be effective for 48 hours. EEG examinations were given to 29 patients both before and after the test. Four female patients experienced hallucinations during the first 4 hours. No conclusions were reached regarding the relation of deviant phenylalanine levels to psychoses. Six patients experienced a remission of psychotic symptoms beginning 2 to 3 weeks after the experiment. A decrease in psychotic symptomatology was seen in 16 depressive patients. 11 references.
Evaluation of the relative potency of individual competing amino acids to tryptophan transport in endogenously depressed patients.
Psychiatry Research 3(2):141-150, 1980
The relative potency of the individual amino acids as competitive inhibitors of tryptophan transport into the human brain was evaluated retrospectively; the combination of competitors that yields the highest predictive value of the plasma tryptophan ratio for the course of treatment of depressed patients with L-tryptophan was also examined. Phenylalanine consistently reduced, and isoleucine slightly reduced the predictive value of the plasma tryptophan ratio. The ratio of tryptophan to the sum of valine, leucine, and tyrosine was identified as most predictive for the therapeutic response to tryptophan. L-tryptophan responders showed a normal plasma total tryptophan concentration as did the nonresponders, whereas the concentration of the three competitors was significantly elevated. It is concluded that while the plasma ratio of tryptophan to the sum of valine, leucine, and tyrosine is a useful predictor of the course of depressives on L-tryptophan, it does not definitely separate out the L-tryptophan responders from the control subjects.
Amino acids in mental illness.
Biological psychiatry today. Vol. B Amsterdam, Elsevier/North Holland, 1979, p1581-4
Research on the influence of several aromatic amino acids in psychiatric disturbances is reviewed, with emphasis on phenylalanine, tyrosine, and tryptophan. The principles of a dopaminergic theory of schizophrenia and of levodopa therapy in neuropsychiatric disorders are treated, along with the role of phenylalanine in phenylketonuria, depression, and schizophrenia. The relation of tryptophan to Hartnup disease, schizophrenia, depression, manic-depression, manic-depressive illness, insomnia, and obsessive-compulsive disorders is also treated. It is concluded that these compounds have important roles in brain physiology and may be involved in the physiopathology of certain mental disorders and/or their treatment.
Depression, pregnancy and phenylalanine.
Neuropisiquiatria (Buenos Aires) 8(1):60-64, 1977
A case study of a mentally depressed pregnant woman who was successfully treated with phenylalanine is reported. The subject was a 34-year-old Argentine woman, married for 5 years and childless. Once the subject was administered phenylalanine, her condition improved. It is noted that a heightened dosage of the drug is required during pregnancy, and that this has no complicating effect on the mother or the child. To check this, the subject's baby was observed for a year after birth. The physiological action of the drug is analyzed, and the progress of the treatment through pregnancy is charted. 17 references.
Theoretical and therapeutic potential of indoleamine precursors in affective disorders.
Neuropsychobiology (Basel) 3(4):199-233, 1977
Research studies investigating the strategy of loading with precursor amino acids of the monoamines, postulated to be involved in the affective disorders, are reviewed. Phenylalanine, tyrosine, L-dopa, L-tryptophan and L-5-hydroxytryptophan (L-5-HTP) were found to induce differential behavioral and biochemical effects in both healthy subjects and endogenous depressives. Indoleamine precursors predominantly caused mood changes. However, it is argued that the efficiency of these amino acids as antidepressants was neither clearly established nor refuted due to insufficient consideration of the following criteria: 1) sufficiently high plasma levels to be taken up into the brain; 2) effective stimulation of serotonergic systems; and 3) selective increase of serotonin turnover with minimal interaction with other neurotransmitters. It is suggested that the use of intravenous L-5-HTP as a provocative test in depressive patients with concomitant neuroendocrinological and psychometric measurements, may be a method of adequately fulfilling these requirements.
Phenylethylamine and glucose in true depression.
Journal of Orthomolecular Psychiatry (Regina) 5(3):199-202, 1976
The relationship between urinary phenylethylamine (PEA) and oral glucose tolerance tests in true depression was investigated in 12 depressives who were resistant to psychotherapy, chemotherapy, and electroconvulsive shock therapy. All medication was discontinued 72 hours prior to testing. Urinary PEA was measured 24 hours before and 72 hours after patients were placed on a 350g carbohydrate load diet. Clinical psychiatric examinations were also performed before, during, and after this treatment. Results revealed severely depressed PEA levels in all patients and disturbed glucose metabolism in 10 of the 12. Improvement was shown by the fifth day of the diet, and good remission of symptoms began by the second week. Side effects, which included mild headache, low blood pressure, and agitation,were few. It is concluded that D-phenylalanine and DL-phenylalanine are thus shown to be antidepressants in true depressives whose illness is caused by biochemical deficiencies, and that the presence of a glucose imbalance in the patients studied may suggest a monoamine disorder as the cause of depression. 28 references.
Therapeutic action of D-phenylalanine in Parkinson's disease.
Arzneimittel-Forschung (Aulendorf) 26(4):577-579, 1976
An open field trial of D-phenylalanine was made in 15 patients with Parkinson's disease of 6 months' to 13 years' duration. All medication was suspended 10 days before the trial, and the patients received only 200mg-500mg D-phenylalanine daily, divided into 2 doses, for 4 weeks. Positive results were highly significant in relation to rigidity, walking disabilities, speech difficulties, and mental depression, but no significant therapeutic results were obtained in regard to tremor. The therapeutic action on the total development of the disease may be considered highly significant. The results suggest a special cholinergic origin of tremor in Parkinson's disease, and in these cases a combination of the amino acid with anticholinergic agents should be tried.
Effects of D-phenylalanine on clinical picture and phenethylaminuria in depression.
Biological Psychiatry 10(2):235-239, 1975
The administration of D-phenylalanine in 11 cases of depression with low urinary phenethylamine output was studied. It was found that the administration of D-phenylalanine to depressed patients in daily oral doses of 100-200mg produced an improvement of the clinical state associated with an increase in the daily urinary phenethylamine output.
Phenylalanine Effective Against Depression
Treatment of endogenous depression with d,1-phenylalanine and d-phenylalanine is reported. Ss all had long-term endogenous depression, and all had been treated unsucessfully with imipramine like drugs and/or inhibitors of monoamineoxidase. Ss were given daily oral doses of 50mg or 100mg of either drug over a period of 15 days. Complete euthymia was obtained in 74% of the Ss between 1 and 13 days of treatment. Side-effects were minimal and in no case required termination of treatment. 13 references. (Author abstract modified)
Phenylalanine for endogenous depression.
Journal of Orthomolecular Psychiatry (Regina) 3(2):80-81, 1974
Phenylalanine was administered to patients suffering from endogenous depression. Although the experimental trial was short and the dosage small, it seems that some forms of endogenous depression responded well to phenylalanine therapy, mainly with the dextrorotatory form.
