The mental disorder assumes several subtle forms long before the more obvious deterioration of cognitive functions becomes evident. In approximately half the cases, slight but annoying alterations of personality are the first to appear. Patients begin to find fault with everything, to complain constantly, and to nag other members of the family; they may be suspicious, irritable, impulsive, eccentric, untidy, or excessively religious, or they may exhibit a false sense of superiority. Poor self-control may be reflected in outbursts of temper, fits of despondency, slovenliness, alcoholism, or sexual promiscuity. Disturbances of mood, particularly depression, are common (almost half of the patients in some series) and may constitute the most prominent symptoms early in the disease. Invariably, sooner or later, the intellect begins to fail globally. The patient becomes less communicative and socially withdrawn. The emotional disturbances and changes in personality may reach such proportions as to constitute a virtual psychosis with persecutory delusions or hallucinations.
Diminished work performance, inability to manage household responsibilities, and disturbances of sleep may prompt medical consultation. There is difficulty in maintaining attention and concentration and in assimilating new material. Mental flexibility lessens. Simultaneously, there is loss of fine manual skills (see further on). The performance parts of the Wechsler Adult Intelligence Scale show greater loss than the verbal parts. Memory is relatively spared. This gradual dilapidation of intellectual function has been characterized as a “subcortical dementia,” that is elements of aphasia, agnosia, and apraxia are observed only rarely and memory loss is not profound. Often the process is so slow, particularly in cases of late onset, that a fair degree of intellectual capacity seems to be retained for many years.
The abnormality of movement is subtle at first and most evident in the hands and face; often the patient is merely considered to be fidgety, restless, or “nervous.” Slowness of movement of the fingers and hands, a reduced rate of finger tapping, and difficulty in performing a sequence of hand movements are early signs. Gradually these abnormalities become more pronounced until the entire musculature is implicated with chorea. The frequency of blinking is increased (the opposite of parkinsonism), and voluntary protrusion of the tongue, like other attempts at sustained posture, is constantly interrupted by unwanted darting movements. In the advanced stage of the disease the patient is seldom still for more than a few seconds. The choreic movements are slower than the brusque jerks and postural lapses of Sydenham chorea, and they involve many more muscles. They tend to recur in stereotyped patterns yet are not as stereotyped as tics. In advanced cases, they acquire an athetoid or dystonic quality. Muscle tone is usually decreased until late in the illness, when there may also be some degree of rigidity, tremor, and bradykinesia, elements suggestive of Parkinson disease. Parkinsonism with rigidity characterizes the Westphal or “rigid” variant, which is more common with a childhood onset, or the HDL2 genetic variant noted earlier. Tendon reflexes are exaggerated in one-third of patients, but only a few have Babinski signs. Voluntary movements are initiated and executed more slowly than normal, but there is no weakness and no ataxia, although speech, which becomes dysarthric and explosive because of incoordination between tongue and diaphragm, may convey the impression of a cerebellar disorder. Inability to hold the tongue protruded is characteristic. In late-onset cases there may be an almost constant rapid movement of the tongue and mouth, simulating the tardive dyskinesia that follows the use of neuroleptic drugs. These disorders of movement that characterize Huntington chorea are described more fully in Chap. 4.