Urinary phenylacetate and response to methylphenidate.
Phenylacetate (PAA) is the metabolic end-product of phenylalanine, a catecholamine precursor, and of phenylethylamine, a centrally active neurochemical substance which has been implicated in the actions of stimulant medications. PAA has been reported to be low in unipolar depression. We measured 24-h urinary PAA in normal controls (N = 21) and in-patients with unipolar depression (N = 33; 12 drug-free) and did subsequent dexamethasome suppression tests (DST). We also gave patients methylphenidate challenges, examining mood response. There were no significant differences between depressed patients and controls in 24-h urinary PAA excretion (P greater than 0.9). However, the variance in PAA excretion was higher in patients than normals and 5 patients had values at or above the 99% confidence limits for the normal control group. There was no association of DST results with PAA excretion (P greater than 0.4). Patients with a worsened mood after taking methylphenidate excreted less PAA than those with an improved mood, however (P less than 0.025). The clinical and theoretical significance of these results is discussed.
Baxter
L R
LR
Department of Psychiatry and Biobehavioral Science, UCLA School of Medicine 90024.
Kelly
R C
RC
Peter
J B
JB
Liston
E H
EH
Touserkani
S
S
D000328:Adult; D000368:Aged; D003866:Depressive Disorder / Q000175:diagnosis / Q000188:drug therapy* / Q000652:urine; D003907:Dexamethasone; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D008297:Male; D008774:Methylphenidate / Q000627:therapeutic use*; D008875:Middle Aged; D010648:Phenylacetates / Q000652:urine*; D011379:Prognosis; D011581:Psychological Tests
D010648:Phenylacetates; D008774:Methylphenidate; D003907:Dexamethasone; C025136:phenylacetic acid; D006854:Hydrocortisone