Six girls with Rett syndrome and two boys with Heller dementia are reported and contrasted with children with classic autism from the Department of Neuroscience and Pediatrics, University of North Dakota School of Medicine, Grand Forks, North Dakota, and the Kennedy Institute, Johns Hopkins Medical Institutions, Baltimore, MD. The study was performed in response to a report that Rett syndrome may be a form of Heller dementia with a predilection for girls . All eight children differed from those with classic autism in that they had normal prenatal and perinatal periods, followed by marked developmental regression, after which they acquired few or no skills. The boys with a diagnosis of Heller dementia differed from the girls with Rett syndrome in terms of estimated prevalence, age at onset, stereotypic breathing patterns, midline hand stereotypies, hand and gait apraxia, and speech development. The authors found no stereotyped movements in their two patients with Heller dementia although these have been described in other studies. The patients showed similarities in the normal prenatal and perinatal periods, behavioral, social and psychomotor regression, and epilepsy. The authors suggested that these children should be distinguished from those with classic autism and should be classified as “pervasive disintegrative disorder, Heller type” and “pervasive disintegrative disorder, Rett type”. 
COMMENT. In 1908, almost 60 years before the first description of Rett syndrome, Heller reported an infantile dementia with symptoms and a course similar in some respects to that of Rett syndrome. By 1930, Heller had collected 28 cases of dementia in young children who previously had been entirely normal in development. Without antecedent illness, a change in mood and behavior was noticed. The children became irritable, negativistic, and disobedient; they had outbursts of temper without provocation; they showed signs of anxiety; and a mental regression led to a complete loss of speech and deterioration within a few months. Motor restlessness and stereotyped repetitive movements and mannerisms with grimacing and tics were most conspicuous. Seizures and growth retardation were mentioned in later reports. The cause was unknown but a suspected organic lesion was confirmed in cases examined at necropsy. Diffuse lipoid cell degeneration of the cortical neurons, atrophy of the brain, small disorganized cortical neurons lacking in Nissl bodies, and marginal gliosis have been described, and abnormalities in plasma lipids. Heller dementia is recognized as a syndrome in text books of pediatric neurology and child psychiatry although some have suggested that some examples of the syndrome may have been confused with childhood schizophrenia, and other degenerative brain diseases. Heller dementia occurs in both boys and girls and unlike Rett syndrome, the disorder was not restricted to girls. It is surprising that in publications on Rett syndrome Heller dementia seems to have been overlooked in the differential diagnosis. Drs. Rett and Olsson have now corrected this omission  but believe that research will show Rett syndrome to be an independent disorder. They admit that the differentiation may be difficult in older children and that the range of variations of both syndromes cannot be determined until the etiology is known. The suggestion that most cases of Heller dementia were disintegrative psychoses  does not fit with published neuropathological findings, and the introduction of the term “pervasive disintegrative disorder, Heller type and Rett type”, based on two patients in the present report, is probably not of value in the classification of these dementias.