Phenylthiocarbamide (PTC) tasting and depression: a possible genetic link

The phenylthiocarbamide (PTC) taste test was investigated as a potential genetic link to depression. Twenty-three subjects, ages 25-55, who met NIMH's Diagnostic Interview Schedule (DIS), DSM-III criteria for Major Depression, current, were given the Beck Depression Inventory (BDI), the Hamilton Rating Scale for Depression (HRS), and a five-item scale measuring major psychosocial stressors. A three-generation family history of depression was elicited from each subject utilizing DSM-III criteria. After the above was obtained, each subject took the PTC (paper) taste test, and provided a 24-hour urine specimen.

PTC tasters (N = 14) were more severely depressed than nontasters (N = 9) on both BDI and HRS (p < .03). More tasters than nontasters reported depressions lasting two years or more (p < .05). These differences could not be explained by differences in measured major psychosocial I stressors or age. The majority of the most distinctive symptoms of depressed tasters fit an endogenous depression subtype. Depressed tasters reported a higher incidence of family depression (p < .01). No difference in 24-hour urinary MHPG or PAA was found between tasters and nontasters.

To this depressed sample was added a group of females (N = 18), ages 27-60, who went through the same procedure as described above and who satisfied DIS:DSM-III criteria for no history of depression. PTC taste status was a better predictor of depressed status and of depression severity than either MHPG or PAA, but was less powerful than the scale of psychosocial losses. Nontasters were overrepresented in the never depressed group (p < .005). Taste status was normally distributed in the depressed group. Limitations and implications of these findings are discussed.