are the distinction between pathoand non-pathological unhappiness, the relation between neurotic (reactive) and psychotic (endogenous) depression, and separation of unipolar (depression alone) from bipolar illnesses, in which depression and mania occur at different stages of illness.Throughout the history of psychiatry the classification of depression has been controversial, some workers maintaining that pathological depression constitutes a continuum with no clear distinctions between the forms of illness,9 -11 others subdividing depression into two or more clear-cut categories2-15 Resolution of this argument has important practical implications. Treatments for depression include the range of psychotherapies, drugs, and electroplexy (E.c.T.), and these should be applied rationally. For example, there is considerable evidence that physical treatments are more appropriate for psychotic than for neurotic depression, 13, 16 so this distinction should be made before the start of treatment. Nevertheless, separation of depression on clinical features alone is crude and for many years attempts have been made to find biochemical and other objective measnres of depression so that classification can be freed from the vagaries of clinical description. A fruitful theory in biochemical research on depression has been the catecholamine hypothesis, which in its simplest form states that pathological depression is due to a relative deficiency in cerebral catecholamines. t7 Although later evidence has modified and eroded much of the original hypothesis1s-2O the possibility that variation in catecholamine metabolism might account for differences in types of depression has been explored energetically. Noradrenaline is metabolised to 3-methoxy-4hydroxyphenylglycol (M.H.P.G.) and is excreted in this form from the kidneys. Although only a small proportion of urinary M.H.P.G. originates from brain noradrenaline most workers have found reduced urinary M.H.P.G. levels in depression 21, 22-with great variation between patients. 23 Some of this variation may be due to biochemical differences in certain types of depression. Schildkraut and his colleagues have found that M.H.P.G. excretion is significantly lower in the depressed phase of bipolar manic-depressive psychosis, and in the depressed phase of schizoaffective disorder, than in non-endogenous depression.24 They have further divided depression into three groups on the basis of catecholamine metabolites.25 Unfortunately the commonest form of
depressive illness, unipolar depression,
8. Perris, C.Acta psychiat. Scand. 1966, suppl. 194. 9. Mapother, E. Br. med.J. 1926, ii, 872. 10. Lewis, A. J. ibid. 1938, ii, 875. 11. Kendell, R. E. The Classification of Depressive Illnesses. London, 1968. 12. Kiloh, L. G., Garside, R. F. Br.J. Psychiat. 1963, 109. 451. 13. Carney, M. W. P., Roth, M., Garside, R. F. ibid. 1965, 111, 659. 14. Eysenck, H. J. ibid. 1970, 117, 241. 15. Paykel, E. S. ibid. 1971,118,275. 16. Bielski, R. J, Friedel, R. O.Archs gen. Psychiat. 1976, 33, 1479. 17. Schildkraut, J. J. Am.J. Psychiat. 1965, 122, 509. 18. Mardell, A. J., Spooner, C. E. Science, 1968, 162, 1442. 19. Ashcroft, G. W. Lancet, 1972, ii, 573. 20. Mendels, J., Frazer, A. Archs gen. Psychiat. 1974, 30, 447. 21. Maas, J. W., Fawcett, J. A., Dekirmenjian, H. ibid. 1968, 19, 129. 22. Fawcett, J. A., Maas, J. W., Dekirmenjian, H. ibid. 1972, 26, 246. 23. Maas, J. W., Fawcett, J. A., Dekirmenjian, H. ibid p.252. 24. Schildkraut, J. J., Orsulak, P. J., Schatzberg, A. F., Gudeman, J. E., Cole, J. O., Rohde, W. A., LaBrie, R. A. ibid. 1978, 35, 1427. 25. Schildkraut, J. J., Orsulak, P. J., LaBrie, R. A., Schatzberg, A. F., Gudeman, J. E., Cole, J. O., Rohde, W. A. ibid. p. 1436.
in Schildkraut’s classification. This may be unipolar depression is itself heterogeneous. Winokur and his colleagues have suggested that depression spectrum disease, in which a first-degree family member has an antisocial personality or alcoholism, is an autonomous depressive subgroup,26,27 and their most recent study28 supports this separation. Serum-cortisol response to the overnight dexamethasone test distinguished depression spectrum disease from "pure" depressive illness (with genetic predisposition) and sporadic depressive disease (with no family history of depres-
sion). Whilst it needs to be replicated by other investigators and cautious interpretation is needed after the disappointments with previous biochemical findings in depression,29 this work does seem to be an important advance. It needs to be consolidated by determination of other clinical correlates of the depressive subtypes and their response to treatment. Clinical and biochemical classifications should interleave and reinforce each other to achieve their full value.
FORTUNATELY, people who are affected by motion sickness usually lose this susceptibility when they are in the driver’s seat, but on naval vessels everyone on board has a job to do. Naval medical departments have been at the forefront in the evaluation of the drug prophylaxis of seasickness, and, since effective drugs cause drowsiness, this evaluation has to include performance: for new recruits yet to acquire their sea-legs the choice may be between seasickness and sleepiness. A group from the Naval Submarine Medical Research Laboratory, at Groton, Connecticut, has taken the evaluation of one popular and readily available seasickness pill a step further. Their concern was with the effects on vision of ’Dramamine’ (the theoclate salt of the antihistamine diphenhydramine, otherwise known as dimenhydrinate). Sixteen young submariners, acting as their own controls, took part in a double-blind study of or dimenhydrinate and placebo. The dimenhydrinate dose was on the high side (300 mg in a day) and the battery of tests was onerous, though no less so than a typical six-hour watch on the dial-packed decks of a submarine. Dimenhydrinate slowed reaction-times, as might be expected, but it also affected colour discrimination and night vision; stereopsis was also adversely affected. Aspirin, on the other hand, seemed to have no significant effects of practical importance. Night-vision scores fell by 20%, so it will be important to confirm that what is true in the laboratory tests holds for work at sea. Meanwhile perhaps these young men should take comfort in the fact that Nelson, who was not immune to seasickness, managed very well with only one eye and, on one occasion, with neither.
26. Winokur, G., Cadoret, R., Dorzab, J., Baker, M. ibid. 1971,24,135. 27 Winokur, G. ibid. 1979,36,47. 28. Schlesser, M. A., Winokur, G., Sherman, B. M. Lancet, 1979, i, 739. 29. ibid. 1978, i, 422. 1. Luria, S. M., Kinney, J. A. S., McKay C. L., Paulson, H. M, Ryan, A P Br.J. clin. Pharmac. 1979, 7, 585.