The Clinical Importance of the Neuroleptic Threshold and its Fine Motor Determination by the Handwriting Test

This paper discusses the present state of investigations concerning the concepts of ‘neuroleptic threshold’ and fine motor extrapyramidal inhibition. The publication also includes reports on studies carried out by thirty-one collaborators from the Haase work-team based on over 50,000 handwriting tests. The main results of the following studies are presented and discussed: Investigations effected by fourteen authors on 328 cases of schizophrenia proving the close relationship between crossing the neuroleptic threshold and onset of the anti-psychotic effect. By a gradual increase of dosage a neuroleptic-anti-psychotic action was obtained in the days following the crossing of the neuroleptic threshold for a total of 87% of cases, 52% of which took place in the first three days, another 16% within the following three days and the rest after a longer interval. In another series of investigations the actions of a neuroleptic drug above and under the neuroleptic threshold were systematically compared in twenty-four cases of chronic schizophrenia. Concerning the action of anti-parkinson drugs on motor and psychic neuroleptic efficiency, results are reported on two series of investigations. Furthermore, the concepts of ‘neuroleptic-therapeutic range’ and ‘neuroleptic potency’ are defined and the problem of different individual predispositions to the neuroleptic threshold is discussed. Fine motor extrapyramidal handwriting symptomatology was quantified by means of Haase's handwriting test and evaluated according to the following degrees: mild, moderate and severe. The relevancy of determining the impressive character of handwriting was proved by the work of three different independent investigators, each separately assessing the samples resulting from the same 300 handwriting tests. Two measuring procedures were evolved for the planimetric evaluation of handwriting. The application of handwriting tests in the therapy of long-term neuroleptics is discussed, viz. in determining duration of activity, in controlling cumulative tendency and in studies on under-threshold neuroleptic action. This paper stresses the clinical and practical importance of these results.